KR100555228B1 - Method and apparatus for improving the uniformity of distribution of a phosphorus-containing agent throughout a maleic anhydride catalytic reactor - Google Patents

Abstract

A method and apparatus for producing maleic anhydride by reacting a hydrocarbon having at least four linear carbon atoms with an oxygen molecule in a catalytic reactor, the reactor comprising a vanadium-phosphorus for catalytic oxidation of hydrocarbon to maleic anhydride. A reactor comprising a fixed catalyst bed having an active site comprising an oxygen catalyst, wherein the process further comprises introducing phosphorus-containing material continuously or intermittently into the reactor. The introduction of phosphorus containing material into the maleic anhydride production system is controlled to provide a more uniform distribution of phosphorus containing material throughout the reactor. The process of the present invention is effective in reducing deposition of phosphorus-containing materials and decomposition products of phosphorus-containing materials on the reactor surface in addition to the catalyst bed, thus reducing reactor maintenance costs and increasing reactor life.

Description

METHODS AND APPARATUS FOR IMPROVING THE UNIFORMITY OF DISTRIBUTION OF A PHOSPHORUS-CONTAINING AGENT THROUGHOUT A MALEIC ANHYDRIDE CATALYTIC REACTOR}

1 is a view of one embodiment of the manufacturing process of maleic anhydride according to the present invention.

FIG. 2 is a diagram showing another specific example of the manufacturing process of maleic anhydride shown in FIG. 1.

Figure 3 shows another embodiment of the process for producing maleic anhydride according to the present invention, in which the phosphorus carrier hydrocarbon feed stream is split into a plurality of maleic anhydride catalytic reactors.

4 compares the standard deviation of trimethyl phosphate in a reactor feed stream as a function of time for (a) addition of trimethyl phosphate controlled by a metering pump and (b) addition of trimethyl phosphate controlled by a pressurized nitrogen feed tank. It shows a curve.

Corresponding reference numerals indicate parts corresponding to those in FIG.

The present invention relates to a process for the production of maleic anhydride by oxidation of hydrocarbons having at least 4 linear carbon atoms in a catalytic reactor. More specifically, the present invention relates to a method for improving the uniformity of the distribution of phosphorus containing material in maleic anhydride catalytic reactors.

Maleic anhydride is one of the important commercial items worldwide. Maleic anhydride is used either alone or in combination with other acids in the preparation of alkyl and polyester resins. It is also used as a versatile intermediate for chemical synthesis.

Maleic anhydride is traditionally prepared by passing a gas containing hydrocarbons and oxygen having at least four straight carbon atoms through a catalyst bed, typically a fixed catalyst bed tubular plug flow reactor, comprising a catalyst comprising a mixed oxide of vanadium and phosphorus. It became. The catalyst used may further comprise promoters, activators or modifiers such as iron, lithium, zinc, molybdenum, chromium, uranium, tungsten and other metals, boron and / or silicon. have. The reaction product gas produced includes carbon monoxide, carbon dioxide, water vapor, acrylic acid and acetic acid and other byproducts with maleic anhydride, as well as an inert gas present in the air when air is used as the source of oxygen molecules.

Since the reaction is highly exothermic, the reactor must be cooled during operation. Typically a shell and tube type heat exchanger is used as a reactor with a catalyst in a tube through which hydrocarbons and oxygen gas pass. Often a cooling fluid using molten salt flows out to cool the outside of the tube. In general, because the length of the tube is much larger than the diameter of the tube, the reaction system is close to the plug flow.

The cooling capacity is substantially uniform throughout the reactor, but the reaction rate varies significantly with the temperature of the hydrocarbon reactants and the reaction zone. Since the reactant gas is usually at a relatively low temperature when injected into the catalyst bed, the reaction rate is low in the area immediately adjacent to the inlet of the reactor. However, once the reaction is started, the reaction proceeds rapidly because the reaction rate is further increased as the reaction zone temperature increases due to the heat released by the reaction. The reaction zone temperature is reduced by the depletion of hydrocarbons until the reaction zone temperature due to heat transfer to the cooling fluid is reduced and the remainder of the reactor tube is allowed to operate at differentially low temperatures. It continues to increase with distance in the direction. The hottest point reached in the reactor tube is generally referred to as a "hot spot."

If the temperature is too high at the hot spot of the reactor, problems may arise in the operation of the reactor. In general, the reaction rate changes in proportion to the reaction temperature, but the selectivity of the catalyst changes in inverse proportion to the reaction temperature. The high reaction zone temperature results in low catalyst selectivity, which favors the complete oxidation of the hydrocarbon feedstock to carbon dioxide and water rather than maleic anhydride. As the hot spot temperature increases, the amount of hydrocarbon feed consumed by the reaction increases, but the yield of maleic anhydride may decrease due to the reduced selectivity of the catalyst. In addition, exposure to excessive temperatures of the catalyst bed may degrade the catalyst. In general, decomposition of such catalysts can reduce the productivity of the operation while also reducing the selectivity of the catalyst at a given temperature. Moreover, because the rate constant increases exponentially with temperature, if the temperature of the reactor becomes too high, the reactor is placed in a thermal runaway state. The high heat of reaction released by converting hydrocarbon feedstock into carbon dioxide and water exacerbates this problem.

To control catalyst activity and improve catalyst selectivity, small amounts of phosphorus compounds may be added to the reaction gas introduced into the reactor. Although the function of the phosphorus compound is not fully understood, it is assumed that phosphorus is lost by the catalyst under catalytic oxidation conditions, and a portion of the phosphorus compound added to the reactant gas is adsorbed by the catalyst. Furthermore, based on the above assumptions, this treatment of catalysts with phosphorus compounds increases or recovers the phosphorus / vanadium ratio of the catalysts at a rate that favors catalyst selectivity, in particular a rate that favors the formation of maleic anhydride over other byproducts. .

This treatment of the catalyst can be further modified by adding water and a small amount of phosphorus compound to the reactant gas introduced into the reactor. The function of this combination is not fully understood, but it is assumed that the addition of water to the reactor gas promotes a relatively even distribution of the adsorbed phosphorus compound across the catalyst bed. In the absence of water, it was observed that phosphorus compounds introduced into the reactant gas tend to deposit in the immediate vicinity of the tubular reactor inlet.

Edwards US Pat. No. 4,701,433 and US Pat. No. 4,810,803 describe water and phosphorus compounds in the catalyst bed of a maleic anhydride reactor in order to partially deactivate a portion of the catalyst bed and make the reactor temperature isothermal. It introduces introduction into the inside. Suitable phosphorus compounds have been described to include alkyl phosphates including alkyl phosphites and trimethyl phosphate. Edwards discloses that the phosphorus compound and water can be added to the feedstock introduced into the reactor, but further discloses that a variety of other methods can be used to add the phosphorus compound and water to the catalyst bed. Such methods include the use of aerosols to deliver phosphorus compounds; The use of suspensions or colloidal solutions of phosphorus compounds; The use of solvents for phosphorus compounds; And addition of phosphorus compounds through diluent gases such as nitrogen. However, Edwards does not specifically inform how the phosphorus compound should be added to the feedstock at any point in the process.

Ebner, U. S. Patent No. 5,185, 455 discloses a method of controlling the rate by adding trimethyl phosphate to an n-butane and oxygen stream entering a maleic anhydride reactor to improve catalyst selectivity without reducing catalyst activity. Doing. Avner describes a system for maintaining an optimal concentration of trimethyl phosphate in a reactor body introduced into the reactor. However, Avner does not specifically inform how or how trimethyl phosphate should be added to the feedstock at any point in the process.

Summary of the Invention

Accordingly, an object of the present invention is to prepare a maleic anhydride; A method of controlling the introduction of phosphorus containing material into the maleic anhydride catalytic reactor; A method of improving the uniformity of the distribution of phosphorus containing material introduced into the maleic anhydride catalytic reactor in the reactor; To promote uniformity of vaporization and distribution of phosphorus containing material in the feed stream before the feed stream is introduced into the maleic anhydride catalytic reactor; And a method of reducing accumulation of phosphorus-containing material (or decomposition products of phosphorus-containing material) on the surface of the maleic anhydride catalytic reactor into which phosphorus-containing material is introduced.

More specifically, it is an object of the present invention to improve the uniformity of the distribution of trimethyl phosphate in the oxygen stream with n-butane introduced into the maleic anhydride catalytic reactor to improve the uniformity of the distribution of trimethyl phosphate throughout the reactor. And / or to reduce the accumulation of phosphorus-containing substances (or decomposition products of phosphorus-containing substances) on the surface of the maleic anhydride catalytic reactor into which trimethyl phosphate is introduced.

Description of Preferred Embodiments

It is well known that a small amount of phosphorus-containing material can be added to the reaction gases introduced into the maleic anhydride catalytic reactor to control catalyst activity and improve catalyst selectivity, but for the development of more effective catalysts hotspot activity in the reactor is known. It is required to use a large amount of phosphorus-containing materials for the control of. As a result, phosphorus-containing materials are significantly deposited (or decomposition products of phosphorus-containing materials) on the reactor surface, in particular the reactor inlet tubesheets, inlet pipes and rupture housings, resulting in increased corrosion and scratching of the surface. Also, due to most of the phosphorus-containing materials entering the inlet and center of the tubesheet, the deposition of phosphorus-containing materials is not uniform. Welding the tubesheet cracks resulting from this deposition is costly. In addition, the lowering of the reaction rate due to the hot spot activity reduces the efficiency of the reaction.

By improving the uniformity of distribution of phosphorus-containing material in the reactor body prior to introducing the gases into the reactor according to the invention, phosphorus-containing material (or in the reaction gases introduced into the maleic anhydride catalytic reactor on the reactor surface) It has been found that it is possible to significantly reduce the deposition and / or accumulation of decomposition products of phosphorus containing material). By improving the uniformity of the distribution of these phosphorus-containing materials or decomposition products of phosphorus-containing materials, for example, it is possible to reduce undesired scratches or corrosion of the reactor surface, reduce the necessary management and increase the service life of the reactor.

The improper distribution of phosphorus-containing materials in the catalytic reactor used to prepare maleic anhydride results in the amount of phosphorus-containing material in some parts of the reactor being below normal or optimal, and therefore in other parts of the phosphorus-containing material. Uneven distribution of phosphorus containing materials in such reactors can adversely affect reactor performance, as this results in more than normal or optimal amounts. Reactor performance can be improved by improving the non-uniformity of the distribution of these phosphorus containing materials or decomposition products of phosphorus containing materials.

For example, in a tubular reactor in which phosphorus-containing material is not evenly distributed throughout the reactor, a catalyst bed containing more than a normal amount of phosphorus-containing material contained in these reactor tubes even though the operation of the tubes is relatively stable. Their deactivation is increased. The hot spots in each tube move further into the catalyst bed but exhibit substantially good behavior. The operation of these reactor tubes is relatively stable, but the conversion of hydrocarbon feedstock introduced into these tubes is generally reduced. In addition, the catalyst beds contained in these tubes generally exhibit good selectivity, but the yield of maleic anhydride from these tubes is reduced due to operation at the top of the reactor or below the target conversion. The reduction in conversion can be reversed, for example, by raising the reaction run temperature. However, such an increase in temperature can reduce catalyst selectivity (and thus increase the production of carbon dioxide and water in the production of maleic anhydride) and accelerate the decomposition of the catalyst. In addition, reactor tubes containing more than normal amounts of phosphorus-containing material may increase the deposition of phosphorus-containing material or decomposition products of phosphorus-containing material on the reactor or tube surface, particularly in reactor inlet tubesheets, inlet pipes, rupture plate housings. have.

In an exemplary tubular reactor, catalyst beds contained within these reactor tubes containing less than normal phosphorus containing materials are not deactivated to the same extent as catalyst beds containing normal amounts of phosphorus containing material. The operation of such tubes becomes less stable and more sensitive to thermal runaway in the catalyst bed under normal operating conditions. These tubes are more sensitively shaken from normal operation, such as a decrease in space velocity. As the average reaction temperature rises, the coolant temperature rises, which compensates for the reduced catalytic activity in the reactor tubes containing more than normal amounts of phosphorus containing material, The reactor tubes operate higher than the target conversion of the hydrocarbon feedstock, resulting in reduced catalyst selectivity due to excessive hot spot temperatures in these tubes.

If the phosphorus-containing material is not evenly distributed throughout the reactor, such problems may arise. In the process according to the invention a more uniform and uniform distribution of the phosphorus containing material introduced into the reactor can be provided, minimizing or eliminating these problems. In particular, the process according to the present invention provides for the deposition of solid or liquid phosphorus-containing substances or decomposition products of phosphorus-containing substances on the reactor surfaces, in particular on the reactor inlet surface, more particularly on the rupture plates of the reactor inlet head, rather than on a catalyst bed, or Reduce accumulation. The method according to the present invention is additionally expected to provide one or more of the following advantageous effects over conventional methods: (1) more consistent and uniform conversion of hydrocarbon feedstock in the tube; (2) lower hot spot temperature in the tube; (3) a low temperature rise over time of the heat transfer medium temperature used to cool the reactor; (4) reduction in catalytic activity and / or stability, and / or (5) yield stability of maleic anhydride, ie, decrease in maleic anhydride yield.

The term "yield" as used for the purposes of the present invention means the molar ratio of the obtained maleic anhydride to the hydrocarbon feedstock introduced into the reaction zone, expressed as mole% multiplied by 100. The term "selectivity" refers to the molar ratio of maleic anhydride obtained with the reacted or converted hydrocarbon feedstock, expressed in mole percent multiplied by 100. By "conversion" is meant the molar ratio of the reacted hydrocarbon feedstock to the hydrocarbon feedstock introduced into the reaction zone, expressed as mole% multiplied by 100. "Space velocity", "gas space velocity per hour" or "GHSV" means the volume of gas supplied per hour expressed in cubic centimeters (cc) at 15.5 ° C, atmospheric pressure divided by the apparent volume of catalyst expressed in cubic centimeters, cc It is expressed as / cc or hour or hour ^-1 .

An illustration of one embodiment of the method and apparatus of the present invention is illustrated in FIG. The maleic anhydride production system according to the invention is indicated generally by the reference number 1. Those skilled in the art will understand that the present invention can be used with catalytic reactors and modes of operation in a variety of configurations, the following description is only intended to illustrate the type of system to which the present invention can be applied.

The hydrocarbon source having at least four linear carbon atoms is introduced into the first mixing zone 5 through the hydrocarbon supply line 3. Phosphorus containing material is introduced into the first mixing zone 5 to produce a phosphorus carrier hydrocarbon feed stream. The phosphorus carrier hydrocarbon feed stream enters the oxygen mixing zone 9 through the first conduit 7 where the phosphorus carrier hydrocarbon feed stream is mixed with oxygen molecules or a gas comprising oxygen molecules to form a reactor feed gas. The oxygen mixing zone 9 is in liquid phase with the tubular reactor 11, and the reactor feed gas enters the tubular reactor 11 where partial catalytic oxidation from the oxygen mixing zone 9 to maleic anhydride proceeds.

The tubular reactor 11 has a cylinder with a cylinder 13, vertically oriented tubes 15, a lower head 17 having a gas inlet 19 and an upper head having a lower gas outlet 21. A tube heat exchanger. The tubes 15 of the reactor are fixed to the lower and upper portions 23, 25 of the tubesheets and filled with catalyst to provide a catalyst component bed 27 in each tube. Combined, the combined tubes 15 constitute a reaction chamber. Inlet 19 is connected to the reactor feed stream and the liquid phase flow.

For phosphorus-containing materials with sufficiently high water vapor pressure under applicable conditions, the introduction of the phosphorus-containing material into the hydrocarbon feed stream may be such that the phosphorous-containing material is substantially vaporized into the reactor feed stream before the reactor feed stream enters the catalyst bed. desirable. More preferably, the introduction of the phosphorus-containing material into the hydrocarbon feed stream is such that prior to the combination of the phosphorus-containing hydrocarbon feed stream with the oxygen or oxygen molecules or at least before the reactor feed stream enters the catalyst bed, At least about 90%, more preferably at least about 95%, and more preferably at least about 99% are vaporized into the phosphorus containing hydrocarbon feed stream.

In the present invention, a method of producing maleic anhydride is improved by reacting a hydrocarbon source having at least four linear carbon atoms with an oxygen molecule in a catalytic reactor. The reactor generally comprises a fixed catalyst bed having an active site comprising a vanadium-phosphorus-oxygen catalyst used for the catalytic oxidation of hydrocarbons to maleic anhydride. Phosphorus-containing materials are introduced into the reactor either continuously or intermittently. In order to improve the distribution of phosphorus-containing material throughout the reactor, the manner in which phosphorus-containing material is introduced into the reactor is controlled.

In one embodiment of the invention, the phosphorus containing material is introduced into a gaseous feed stream comprising hydrocarbons to provide a phosphorus carrier hydrocarbon feed stream. The phosphorus carrier hydrocarbon feed stream is combined with an oxygen molecule or a gas comprising oxygen molecules to form a reactor feed stream. To achieve the desired distribution of phosphorus-containing material throughout the reactor, the introduction of phosphorus-containing material into the hydrocarbon feed stream is adjusted to substantially vaporize the phosphorus-containing material before the reactor feed stream enters the catalyst bed. Hydrocarbons react with oxygen molecules in a reactor to produce a reaction product containing maleic anhydride.

In order to promote the desired vaporization and / or substantially uniform distribution of the phosphorus containing material, the phosphorus containing hydrocarbon material in the phosphorus carrier hydrocarbon feed stream before the phosphorus carrier hydrocarbon feed stream is combined with an oxygen molecule or a gas comprising oxygen molecules. The residence time of is preferably about 3 seconds or more, more preferably about 5 seconds or more, and even more preferably 8 seconds or more. In general, the residence time of the phosphorus containing material in the phosphorus carrier hydrocarbon feed stream is from about 2 seconds to about 90 seconds, preferably in combination with the oxygen molecule or gas comprising the oxygen molecule of the phosphorus carrier hydrocarbon feed stream. About 4 seconds to about 30 seconds, more preferably between about 6 seconds and about 25 seconds, even more preferably between about 8 seconds and about 15 seconds.

While the above preferred dwell times can be expected to include optimal dwell times that can be effectively used in accordance with the present invention, those skilled in the art will appreciate that dwell times can depend on such parameters as piping and reactor structure and space velocity. It will be appreciated that this may vary. For example, a reduction in the residence time of phosphorus containing material in the phosphorus carrier hydrocarbon feed stream prior to combining with the oxygen molecules or gas comprising the oxygen molecules of the phosphorus carrier hydrocarbon feed stream may result in a reactor feed prior to introducing the reactor feed stream into the reactor. It may be possible in certain reactor structures where the residence time of the stream is adequately increased. Thus, the exemplary process should be broadly interpreted to include a residence time sufficient for the phosphorus containing material to be substantially vaporized and / or uniformly distributed in the reactor feed stream before the reactor feed stream enters the catalyst bed.

Thus, in another embodiment, phosphorus containing material is introduced into a gaseous feed stream comprising hydrocarbons to provide a phosphorus carrier hydrocarbon feed stream. The phosphorus carrier hydrocarbon feed stream is combined with an oxygen molecule or a gas comprising oxygen molecules to form a reactor feed stream. To achieve the desired vaporization and / or uniform distribution, the introduction of the phosphorus containing material into the hydrocarbon feed stream is controlled such that the phosphorus containing material is uniformly distributed throughout the reactor feed stream before the reactor feed stream enters the catalyst bed. Hydrocarbons react with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride.

In another embodiment, a phosphorus carrier hydrocarbon feed stream is provided by introducing phosphorus containing material into a feed stream comprising hydrocarbons. The hydrocarbon feed stream is combined with an oxygen molecule or a gas comprising oxygen molecules to form a reactor feed stream. In order to achieve the desired vaporization and / or uniform distribution, the introduction of the phosphorus containing material into the hydrocarbon feed stream is characterized by the presence of phosphorus in the phosphorus carrier hydrocarbon feed stream prior to combining the phosphorus carrier hydrocarbon feed stream with oxygen molecules or gases comprising oxygen molecules. The residence time of the containing material is controlled to exceed 1 second. Hydrocarbons react with oxygen molecules in a reactor to produce a phosphorus containing material comprising maleic anhydride.

In another embodiment, a phosphorus carrier hydrocarbon feed stream is provided by introducing a phosphorus containing material into a feed stream comprising hydrocarbons in the first mixing zone. The phosphorus carrier hydrocarbon feed stream is passed through a conduit to an oxygen mixing zone, where the phosphorus carrier hydrocarbon feed stream is mixed with an oxygen molecule or a gas comprising an oxygen molecule in the oxygen mixing zone to form a reactor feed gas. The residence time of the phosphorus carrier hydrocarbon feed stream in the conduit exceeds 1 second. Hydrocarbons react with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride.

FIG. 2 illustrates alternative embodiments and apparatus of the method of the invention illustrated in FIG. 1. The maleic anhydride production system illustrated in FIG. 2 is almost identical to the maleic anhydride production system illustrated in FIG. 1 except that a gas / liquid contact region is additionally included in the system. In the system illustrated in FIG. 2, a gaseous hydrocarbon source having at least four linear carbon atoms enters the first mixing zone 31 via a hydrocarbon feed line 29. The liquid phosphorus containing material is introduced into the first mixing zone 31 to produce the first phosphorus carrier hydrocarbon feed stream. The first phosphorus carrier hydrocarbon feed stream enters the gas / liquid contacting zone 35 past the first conduit 33 to produce a second phosphorus carrier hydrocarbon feed stream.

The second phosphorus carrier hydrocarbon feed stream enters the oxygen mixing zone 39 through which the second phosphorus carrier hydrocarbon feed stream is mixed with an oxygen molecule or a gas comprising oxygen molecules to form a reactor feed gas. The reactor feed gas flows from the oxygen mixing zone 39 to the tubular reactor 41 where partial catalytic oxidation to maleic anhydride proceeds.

The gas / liquid contact zone provides a means for promoting interfacial contact between the liquid phosphorus-containing material and the gaseous feed stream, such as the average size of droplets entrained within the gaseous hydrocarbon source by providing a surface area for collision of droplets. And means for promoting a uniform distribution of the liquid phosphorus-containing material in the gaseous feed stream and / or means for promoting vaporization of the phosphorus-containing material in the gaseous feed stream. More specifically, the means include means selected from the group comprising, for example, filter media, static mixers, pipe piping and turbulent induction flow devices. The means preferably comprises a filter medium. The filter media, which is a waste type and / or cartridge type after use, may be used such as but not limited to pleated paper filters and winding fiber filters. If the means comprise a filter medium, the phosphorus containing material is preferably introduced upstream of the filter medium or injected directly into the filter medium.

In another embodiment, the liquid phosphorus containing material is introduced into a gaseous feed stream comprising hydrocarbons in a first mixing zone upstream of the gas / liquid contacting zone to produce a phosphorus carrier hydrocarbon feed stream. The gas / liquid contacting zone includes means for facilitating interfacial contact between the liquid phosphorous-containing material and the hydrocarbon feed gas. The phosphorus carrier hydrocarbon feed stream is combined with an oxygen molecule or a gas comprising oxygen molecules downstream of the gas / liquid contacting zone to form a reactor feed stream. Hydrocarbons react with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride.

In another embodiment, a phosphorus carrier hydrocarbon feed stream is produced by introducing a liquid phosphorus containing material into a gaseous feed stream comprising hydrocarbons in a first mixing zone upstream of the gas / liquid contacting zone. The gas / liquid contacting zone includes means for facilitating interfacial contact between the liquid phosphorous-containing material and the hydrocarbon feed gas. The phosphorus carrier hydrocarbon feed stream is combined with an oxygen molecule or a gas comprising oxygen molecules downstream of the gas / liquid contacting zone to form a reactor feed stream. The introduction of the phosphorus containing material into the hydrocarbon feed stream is controlled such that the residence time of the phosphorus containing material in the phosphorus carrier hydrocarbon feed stream between the first and second mixing zones exceeds 1 second. Hydrocarbons react with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride.

In another embodiment, a liquid phosphorus-containing material is introduced into a gaseous feed stream comprising hydrocarbons in a first mixing zone upstream of the filter medium and passed therethrough to provide a phosphorus carrier hydrocarbon feed stream. do. The phosphorus carrier hydrocarbon feed stream is combined with an oxygen molecule or a gas comprising oxygen molecules in an oxygen mixing zone downstream of the filter medium. Hydrocarbons react with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride.

In another embodiment, a liquid phosphorus containing material is introduced into a gaseous feed stream comprising hydrocarbons in a first mixing zone upstream of the filter medium, through which the hydrocarbon feed stream is passed to provide a phosphorus carrier hydrocarbon feed stream. do. The phosphorus carrier hydrocarbon feed stream is combined with an oxygen molecule or a gas comprising oxygen molecules in an oxygen mixing zone downstream of the filter medium. The residence time of the phosphorus carrier hydrocarbon feed stream between the first mixing zone and the oxygen mixing zone exceeds 1 second. Hydrocarbons react with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride.

In the case of phosphorus-containing materials that are present in substantially liquid form prior to entering the reactor, the introduction of the phosphorus-containing material into the hydrocarbon feed stream is such that the phosphorous-containing material is substantially uniformly radial in the reactor feed stream before the reactor feed stream enters the catalyst bed. Is controlled to be distributed. In addition, introduction of the phosphorus-containing material into the hydrocarbon feed stream is preferably carried out in the reactor feed stream with an average particle size of less than about 10 microns, preferably less than about 5 microns, and more preferably between about 1-5 microns. Is controlled to be.

In one embodiment, the phosphorus containing material is introduced into a gaseous feed stream comprising hydrocarbons in the first mixing zone to provide a phosphorus carrier hydrocarbon feed stream. The phosphorus feed feed stream passes through a filter medium that blocks the liquid phosphorus containing material and distributes it in a medium that laterally crosses the flow path of the hydrocarbon feed stream, and thus, as the liquid is recaptured back from the filter medium, phosphorus containing The material is dispersed to promote uniform radial distribution of the liquid phosphorus containing material into the phosphorus carrier hydrocarbon stream. The phosphorus carrier hydrocarbon feed stream is combined with an oxygen molecule or a gas comprising oxygen molecules in an oxygen mixing zone downstream of the filter medium. Hydrocarbons react with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride.

The liquid phosphorous-containing material may be mixed with oxygen-containing gases and recaptured into droplets that exhibit a large surface area effective to promote vaporization of the phosphorous-containing material in the gas stream. The average particle size of the recollected droplets typically ranges from about 1 to about 5 microns. The filter medium generally comprises a porous medium having an average pore size of between about 1 μm and about 10 μm, preferably between about 1 μm and about 5 μm, and the filter medium preferably extends substantially across the entire flow path of the phosphorus carrier hydrocarbon feed stream. Stretched

In another embodiment, the phosphorus containing material is introduced into a gaseous feed stream comprising hydrocarbons in the first mixing zone to provide a phosphorus carrier hydrocarbon feed stream. The phosphorus delivery feed stream passes through a conduit that includes a flow restriction that includes means for dispersing the phosphorus containing material to facilitate uniform radial dispersion of the phosphorous containing material into the phosphorous carrier hydrocarbon stream. The phosphorus carrier hydrocarbon feed stream is combined with an oxygen molecule or a gas comprising an oxygen molecule in an oxygen mixing zone downstream of the means containing the flow restriction. Hydrocarbons react with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride.

Means including flow restriction preferably comprise a gas / liquid contacting area comprising means effective for promoting interface contact between the liquid phosphorous containing material and the hydrocarbon gas. The path through the gas / liquid contacting zone of the phosphorus carrier hydrocarbon feed stream preferably reduces the particle size of the droplets of phosphorus containing material dispersed in the gaseous hydrocarbons, and in particular the phosphorus carrier hydrocarbon stream is characterized by After mixing with a gas containing a reducing to a size effective to promote vaporization of the liquid phosphorous containing material. The gas / liquid contacting zone may include, for example, means for promoting vaporization of the droplets and / or impingement surface to the droplets, including, for example, filter media, static mixers, pipe piping and turbulent induction flow devices. Can be selected from.

In various embodiments of the invention, the minimum residence time of the phosphorus-containing material in the phosphorus carrier hydrocarbon feed stream prior to combining the phosphorus carrier hydrocarbon feed stream with an oxygen molecule or a gas comprising oxygen molecules is determined by the gas / liquid contact zone, dispersion. Means, filter media and the like are not required as long as the phosphorus containing material is substantially vaporized and / or substantially uniformly dispersed in, or contributes to, the reactor feed stream before it enters the catalyst bed. Preferably, however, the minimum residence time is provided in combination with gas / liquid contacting zone, dispersing means, filter media and the like. The residence time of the phosphorus containing material in the phosphorus carrier hydrocarbon feed stream is greater than about 3 seconds, more preferably greater than about 5 seconds, before the phosphorus carrier hydrocarbon feed stream is combined with an oxygen molecule or a gas comprising oxygen molecules. Even more preferably about 8 seconds. Preferably, the residence time of the phosphorus-containing material in the hydrocarbon feedstream is between about 2 seconds and about 90 seconds before the phosphorus carrier hydrocarbon feed stream is combined with an oxygen molecule or a gas comprising oxygen molecules, preferably about 4 seconds. Second to about 30 seconds, more preferably about 6 seconds to about 25 seconds, even more preferably about 8 seconds to about 15 seconds.

The phosphorus containing material may be introduced by any suitable method. However, more preferred are methods that allow the introduction of such materials to more widely disperse phosphorus-containing materials in the hydrocarbon feed stream. Phosphorus containing material may be introduced into the hydrocarbon feed stream, for example, via a tube inserted into the hydrocarbon feed stream, where the tube comprises a fritted tip, through which the phosphorus containing material exits the tube. . In this embodiment, the phosphorus containing material is introduced into the hydrocarbon feed stream through a tube which is inserted into the hydrocarbon feed stream, preferably substantially perpendicular to the flow direction of the hydrocarbon feed stream, wherein the tube passes through the phosphorus containing material. And a fritted tip that can be ejected from the tube.

The temperature of the hydrocarbon feed stream will depend on the specific hydrocarbon selected. If the hydrocarbon is n-butane, the n-butane feed stream is preferably maintained at a temperature of at least about 70 ° C., preferably in the range of about 70 ° C. to about 110 ° C., more preferably from about 85 ° C. to about Between 95 ° C. The phosphorus containing material is preferably preheated before being introduced into the hydrocarbon feed stream. Phosphorus containing material may be introduced into the hydrocarbon feed stream at room temperature but is preferably preheated above about 20 ° C., more preferably above 10 ° C., below the temperature of the hydrocarbon feed stream before being introduced into the hydrocarbon feed stream. . In an embodiment of the invention, the feed line carrying the phosphorus containing material is adjacent to or surrounding the feed line of the hydrocarbon at an appropriate distance prior to introducing the material into the hydrocarbon feed stream to raise the temperature of the mass. In other embodiments, preheating is used, for example, using steam tracing or other suitable method.

Similarly, each of the embodiments disclosed in this application can be further modified by additionally introducing the phosphorus containing material into the phosphorus carrier hydrocarbon feed stream downstream from where the first amount of phosphorus containing material is introduced into the hydrocarbon feed stream. The exact location of the process in which additional phosphorus containing materials may be introduced may vary. Additional phosphorus containing material may be introduced, for example, between the first mixing zone and the oxygen mixing zone, between the first mixing zone and the gas / liquid contacting zone or between the gas / liquid contacting zone and the oxygen mixing zone. The additional phosphorus containing material is preferably introduced at the latest, just before the oxygen mixing zone. In embodiments using separate process streams and a plurality of catalytic reactors as shown in FIG. 3, additional phosphorus containing material is introduced into each separated phosphorus containing hydrocarbon stream, if desired, before the oxygen mixing zone of each separate reactor. It can be explained below. This method makes it possible to individually adjust the rate of forming individual reactor feed streams for various separate catalytic reactors employing phosphorus containing materials. Phosphorus containing material is introduced at a first rate before the process stream is separated to provide a minimum concentration of phosphorus containing material. Additional phosphorus containing material is introduced at a second rate after the process stream is separated, taking into account the individual characteristics of each separate reactor. In this way, the differences depending on the catalyst used, the selectivity and activity of the catalyst and other operational differences for each reactor can be taken into account, and the concentration of phosphorus-containing material in the reactor feed gas to the desired or optimal value for that reactor. I can adjust it. Downstream where additional phosphorus-containing material is introduced from the location of the process in which the phosphorus-containing material was first introduced, the ratio of the first addition rate to the second addition rate of the phosphorus-containing compound is preferably at least about 2: 1, and more Preferably at least about 3: 1, even more preferably at least about 4: 1.

Thus, in one embodiment, the first phosphorus carrier hydrocarbon feed stream is provided by introducing phosphorus containing material into the feed stream comprising hydrocarbons in the first mixing zone at a first rate. The first phosphorus carrier hydrocarbon feed stream passes through the first conduit to the second mixing zone. Additional phosphorus containing material is introduced into the first phosphorus carrier hydrocarbon feed stream in the second mixing zone at a second rate to provide a second phosphorus carrier hydrocarbon feed stream. The second phosphorus carrier hydrocarbon feed stream is passed through a second conduit to an oxygen mixing zone where it is mixed with an oxygen molecule or gas comprising oxygen molecules in the oxygen mixing zone to form a reactor feed stream. The sum of the residence time of the first phosphorus carrier hydrocarbon feed stream between the first and second mixing zones and the residence time of the second phosphorus carrier hydrocarbon feed stream between the second and oxygen mixing zones is greater than one second. Hydrocarbons react with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride.

Figure 3 illustrates an alternative embodiment of another method and apparatus of the present invention wherein a hydrocarbon feed stream comprising phosphorus containing material is separated and directed to a plurality of maleic anhydride catalytic reactors. The maleic anhydride system illustrated in FIG. 3 shows that the phosphorus carrier hydrocarbon stream is partitioned into a separate phosphorus carrier hydrocarbon feed stream before reaching the oxygen mixing zone 33 shown in FIG. It is similar to the maleic anhydride production system illustrated in FIG. 1 except that an additional mixing zone introduced into it is included in the figure. 3 further streams are possible, but for the purpose of illustrating this embodiment, two separate streams are shown: the first reactor hydrocarbon feed stream and the second reactor hydrocarbon feed stream.

The first reactor hydrocarbon feed stream is passed through a first reactor hydrocarbon feed line 43 where additional phosphorus containing compounds are optionally introduced into the first reactor hydrocarbon feed stream at a first reactor speed to form a first reactor carrier hydrocarbon feed stream. The first reactor mixing zone 45 is introduced. The first reactor, the carrier hydrocarbon feed stream, is then introduced into the first reactor oxygen mixing zone 47 and mixed with oxygen molecules or a gas comprising oxygen molecules to form the first reactor feed gas. The first reactor feed gas enters the first reactor oxygen mixing zone 47, partly into the first tubular reactor 49 where catalytic oxidation to maleic anhydride proceeds.

Similarly, the second reactor hydrocarbon stream is second from the second reactor hydrocarbon feed line 51 where additional phosphorus containing compounds are introduced into the second reactor hydrocarbon feed stream, optionally at a second reactor speed, to form a second reactor, a carrier hydrocarbon feed stream. It is introduced into the reactor mixing zone 53. The second reactor, the carrier hydrocarbon feed stream, is then introduced into the second reactor oxygen mixing zone 55 and mixed with oxygen molecules or a gas comprising oxygen molecules to form a second reactor feed gas. The second reactor feed gas is introduced from the second reactor oxygen mixing zone 55 into the second tubular reactor 57 where partial catalytic oxidation to maleic anhydride proceeds.

The rate at which phosphorus containing material is introduced into the respective mixing zones is controlled by one or more controller means 59 which receive information from the flow measuring means 61, 63 and 65. The controller means 59 is preferably a PID type controller. The flow measuring means 61 measures the flow rate of the hydrocarbon feed stream before the hydrocarbon feed stream is separated. The flow measuring means 63 measures the flow rate of the oxygen or oxygen containing feed stream introduced into the oxygen mixing zone of the first reactor. The flow measuring means 65 measures the flow rate of the oxygen or oxygen containing feed stream introduced into the oxygen mixing zone of the second reactor. Set points corresponding to the target concentration of phosphorus containing material in the first reactor feed stream and the target concentration of phosphorus containing material in the second reactor feed stream are input to the controller means 59. These control points are usually determined by an operator or management computer based on, for example, the evaluation of the yield of maleic anhydride, hot spot temperature and other variables specific to each reactor. Then, a control point is input to the controller means 59 corresponding to the target ratio of phosphorus-containing material introduced in the first mixing zone (before the stream is separated) to the total phosphorus-containing material introduced into the whole system.

In operation, the controller means 59 receives the flow information of hydrocarbons and oxygen from the flow measuring means 61, 63 and 65, and then (1) the phosphorus containing material has two concentrations for the first reactor feed stream and the second reactor feed stream. Calculate the velocity that must be introduced (as a function of the measured flow rate) to reach the lower of the control points, and (2) determine the first velocity at which phosphorus containing material should be introduced into the first mixing zone. To determine, reduce the speed calculated above in accordance with the rate control point. The controller means 59 then regulates the introduction of the phosphorus containing material into the first mixing zone according to the calculated first speed.

Controller means 59 then determines the rate at which additional phosphorus containing material must be introduced into the first reactor hydrocarbon feed stream in order to reach a concentration control point specific to the first reactor feed stream (as a function of hydrocarbon and oxygen flow rates). Calculate Similarly, the controller means 59 then determines the rate at which additional phosphorus containing material must be introduced into the second reactor hydrocarbon feed stream in order to reach a specific concentration control point of the second reactor feed stream (function of hydrocarbon and oxygen flow rates). Calculate. The controller means 59 then appropriately regulates the introduction of the phosphorus containing material into the first reactor mixing zone and the second reactor mixing zone according to the calculated first reactor speed and second reactor speed.

Those skilled in the art will appreciate that the procedure described in FIG. 3 allows the reactor feed stream to be fed into a plurality of reactor feed streams introduced into separate catalytic reactors instead of separating the phosphorus carrier hydrocarbon stream as shown in FIG. It will be appreciated that the separation can be successfully transformed. Separate reactor feed streams do not necessarily have, but have the same flow rate. These flow rates can be adjusted to account for the difference in capacity of the reactors used.

Thus, in one embodiment, the supply of phosphorus containing material is divided into a first feed delivered to the first mixing zone and a second feed delivered to a second mixing zone downstream of the first mixing zone with respect to the hydrocarbon gas flow to the reactor. . The flow rate of hydrocarbon gas entering the first mixing zone is measured. The first feed of phosphorus containing material is introduced into the hydrocarbon gas in the first mixing zone to feed the first phosphorus carrier hydrocarbon stream. The rate at which the first feed of phosphorus containing material is introduced into the first mixing zone is adjusted based on the measured hydrocarbon gas flow rate to provide a predetermined concentration of the predetermined phosphorus containing material in the first phosphorus carrier hydrocarbon stream exiting the first mixing zone. do.

A second feed of phosphorus containing material is introduced into the first phosphorus carrier hydrocarbon stream in the second mixing zone to produce a regulated phosphorus carrier hydrocarbon stream. The rate at which the second feed of phosphorus containing material is introduced into the second mixing zone corresponds to a predetermined concentration having a ratio of hydrocarbon to phosphorus containing compound effective to provide a target concentration of phosphorus in the reactor feed gas entering the catalyst bed. It is controlled to provide the total concentration of phosphorus containing material in the regulated phosphorus carrier hydrocarbon stream. The regulated phosphorus carrier hydrocarbon feed stream is mixed with oxygen molecules to provide a reactor feed stream. Hydrocarbons react with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride.

The second feed of the phosphorus carrier hydrocarbon stream and the phosphorus containing material exiting the first mixing zone may be divided into a plurality of second streams which are fed separately to a plurality of second mixing zones downstream of the first mixing zone, each second mixing zone. The controlled phosphorus carrier hydrocarbon feed stream exiting the field can be delivered to each corresponding reactor of the plurality of reactors provided from a separate second mixing zone. The concentration of phosphorus containing material in the phosphorus carrier hydrocarbon stream exiting the first mixing zone is preferably a hydrocarbon to phosphorus containing compound that can each provide the lowest target concentration of phosphorus in reactor feed gases entering the catalyst beds of the plurality of reactors. Is less than or equal to a predetermined concentration having a ratio of. More preferably, the rate at which the phosphorus containing compound is introduced into each of the plurality of second mixing zones is controlled to provide a hydrocarbon to the target concentration of phosphorus in the reactor feed gas that is present in the second mixing zone and enters the catalyst bed into which the stream enters. It provides a predetermined concentration with a proportion of phosphorus containing compounds.

In another embodiment, the supply of phosphorus containing material is divided into a first feed delivered to the first mixing zone and a second feed delivered to a second mixing zone downstream of the first mixing zone with respect to the flow of hydrocarbon gas to the reactor. . The flow rate of hydrocarbon gas entering the first mixing zone is measured. The first feed of phosphorus containing material is introduced into the hydrocarbon gas in the first mixing zone to feed the first phosphorus carrier hydrocarbon stream. The rate at which the first feed of phosphorus containing material is introduced into the first mixing zone is adjusted based on the measured hydrocarbon gas flow rate to provide a predetermined minimum concentration of phosphorus containing material in the first phosphorus carrier hydrocarbon stream exiting the first mixing zone. do.

A second feed of phosphorus containing material and another stream, including the first phosphorus carrier hydrocarbon stream, is introduced into the second mixing zone to produce a regulated phosphorus carrier stream. The rate of introduction of the second feed into the second mixing zone of the phosphorus containing material is controlled to correspond to a predetermined concentration having a hydrocarbon to phosphorus containing compound ratio which can be adjusted to provide a target concentration of phosphorus in the reactor feed gas entering the catalyst bed. The total concentration of phosphorus containing material in the carrier hydrocarbon stream.

The first phosphorus carrier hydrocarbon stream is preferably mixed with the phosphorus containing material introduced into the second mixing zone. More preferably, the first phosphorus carrier hydrocarbon stream is mixed with an oxygen containing gas to produce a regulated reactor feed stream with a preconditioned reactor feed gas to mix with a phosphorous containing material introduced into the second mixing zone to precondition the reactor. Generate feed gas.

In another embodiment, the operation of a plurality of catalytic reactors to produce maleic anhydride by reacting a hydrocarbon having at least four linear carbon atoms with oxygen molecules and vanadium for catalytic oxidation of the hydrocarbon to maleic anhydride. The method comprising each reactor comprising a fixed catalyst bed with an active site comprising an phosphorus-oxygen catalyst is for controlling the continuous or intermittent introduction of phosphorus containing material into the reactor. The flow rate of the feed stream comprising hydrocarbons is measured. The first rate of addition of the phosphorus containing material to be introduced into the hydrocarbon feed stream is calculated. The introduction of the phosphorus containing material into the hydrocarbon feed stream is controlled according to the calculated first addition rate. The first addition rate corresponds to a predetermined minimum addition rate of phosphorus containing material as a function of the flow rate of the hydrocarbon feed stream measured. Phosphorus containing material is introduced into the hydrocarbon feed stream in the first mixing zone to provide the first phosphorus transport hydrocarbon feed stream. The first phosphorus carrier hydrocarbon feed stream is passed through a first conduit to a branch pipe where the first phosphorus carrier hydrocarbon feed stream is divided into a plurality of second hydrocarbon feed streams passing through a series of second conduits to a series of second mixing zones. .

A second rate of addition of the phosphorus containing material to be optionally introduced into each second hydrocarbon feed stream is calculated. The introduction of the phosphorus containing material into each second hydrocarbon feed stream is controlled in accordance with the respective calculated second addition rate. The second rate of addition of phosphorus containing material introduced into each second hydrocarbon feed stream is independent of the second rate of addition of phosphorus containing material introduced into each other second hydrocarbon feed stream. The second addition rate is calculated for each second hydrocarbon feed stream as a function of the measured flow rate of the hydrocarbon feed stream, taking into account the portion of phosphorus-containing material previously introduced into the first mixing zone contained in the second reactor feed stream. And the final target feed rate of phosphorus containing material to the reactor into which the second reactor feed stream is to be introduced. Phosphorus containing material is optionally introduced into each second hydrocarbon feed stream in each second mixing zone to provide a plurality of second phosphorus carrier hydrocarbon feed streams. Each second phosphorus carrier hydrocarbon feed stream is mixed with an oxygen molecule or gas containing oxygen molecules in an oxygen mixing zone to produce a plurality of second reactor feed streams that are introduced into separate catalytic reactors. Residence time between the first mixing zone and the branch pipe of the first phosphorus carrier hydrocarbon feed stream, residence time of the second hydrocarbon feed stream between the branch pipe and the second mixing zone, and second phosphorus between the second mixing zone and the oxygen mixing zone. The sum of residence times of the carrier hydrocarbon feed stream is greater than 1 second. Hydrocarbons react with oxygen molecules in each catalytic reactor to produce a reaction product comprising maleic anhydride.

In another embodiment, the flow rate of the feed stream comprising hydrocarbons is measured. The first rate of addition of the phosphorus containing material to be introduced into the hydrocarbon feed stream is calculated. The introduction of the phosphorus containing material into the hydrocarbon feed stream is controlled according to the calculated first addition rate. The first addition rate is calculated as a function of the measured flow rate of the hydrocarbon feed stream and corresponds to a predetermined minimum addition rate of the phosphorus containing material. Phosphorus containing material is introduced into the hydrocarbon feed stream in the first mixing zone to feed the first phosphorus carrier hydrocarbon feed stream. The first phosphorus carrier hydrocarbon feed stream passes through the first conduit to the second mixing zone.

Optionally, a second rate of addition of the phosphorus containing material to be introduced into the first phosphorus carrier hydrocarbon feed stream is calculated. The introduction of the phosphorus containing material into the first phosphorus carrier hydrocarbon feed stream is controlled in accordance with the calculated addition rate. The second rate of addition is calculated as a function of the measured flow rate of the hydrocarbon feed stream, which is reduced to take into account the phosphorus-containing material pre-introduced in the first mixing zone to the final target rate of phosphorus-containing material to the reactor. Corresponding. The phosphorus containing material is introduced into the first phosphorus carrier hydrocarbon feed stream in the second mixing zone to provide a second phosphorus carrier hydrocarbon feed stream. The second phosphorus carrier hydrocarbon feed stream is combined with an oxygen molecule or gas containing oxygen molecules in an oxygen mixing zone to form a reactor feed stream. The sum of the residence time between the first and second mixing zones of the first phosphorus carrier hydrocarbon feed stream and the residence time between the second and oxygen mixing zones of the second phosphorus carrier hydrocarbon feed stream is greater than 1 second. Hydrocarbons react with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride.

Each embodiment described above with respect to FIG. 3 further includes one or more gas / liquid contacting zones at one point or points between the first mixing zone and the switched mixing zones in the same manner as described with respect to FIG. 2. It can be modified.

Catalytic reactors that can be used according to the invention broadly include any reactor that can be used to convert hydrocarbons having at least four straight-chain carbon atoms to maleic anhydride. In general, the reactor is preferably a tubular reactor in which a heat transfer medium-cooled is fixed. The detailed operation of such reactors is well known to those skilled in the art. The tubes of these reactors may be composed of iron, stainless steel, carbon steel, nickel, glass such as Vycor, and the like. The diameter of the tubes may vary from about 0.635 cm (0.25 in) to about 3.81 cm (1.50 in), and the length may range from about 15.24 (6 in) to about 609.60 cm (20 ft). The oxidation reaction is a high temperature exotherm, and once the reaction proceeds, the heat transfer medium is required to remove heat by transferring heat from the reaction zone to maintain the desired reaction zone temperature. Suitable heat transfer media are well known to those skilled in the art, and in general they are present in the liquid state at the process temperature and have a relatively high thermal conductivity. Examples of useful media include various heat transfer oils, molten sulfur, mercury, salts of molten lead and alkali metal nitrates, nitrites, which salts are preferred because they have a high boiling point. A particularly preferred heat transfer medium is a eutectic mixture of potassium nitrate, sodium nitrate and sodium nitrite, which not only has a desirable high boiling point, but also has a sufficiently low freezing point to remain in the liquid phase even during periods of inactivity of the reaction zone. An additional method of temperature control is to use a metal block reactor or a conventional heat exchanger in which the metal surrounding the reaction zone acts as a temperature regulator.

In general, the operations according to the present invention charge a mixture of oxygen molecule containing gases (including oxygen molecules), such as air, with hydrocarbons having at least four straight-chain carbon atoms, into a catalyst-cooled cooling heat transfer medium reaction zone, and hydrocarbon-oxygen Contacting the catalyst with a gas mixture comprising molecules to produce a reaction product gas comprising maleic anhydride.

The reaction temperature is typically maintained at about 300 ° C to about 600 ° C, preferably about 325 ° C to about 500 ° C. The temperature of the reactor to some extent depends, for example, on the reactor type and the concentration of hydrocarbon and phosphorus containing materials present in the reactor feed stream. The cooling bath used in the reactor is generally kept at a low temperature sufficient to keep the reaction temperature within the desired range.

The reaction pressure is not strictly important. The reaction can be carried out at atmospheric pressure, above atmospheric pressure or below atmospheric pressure. In practice, however, it is usually desirable to carry out the reaction at or near atmospheric. Typically the pressure is about 14.7 psig to about 50.0 psig, more preferably about 16.0 psig to about 30.0 psig, even more preferably about 18.0 psig to about 28.0 psig can be used as convenient. The discharge pressure will be at least slightly higher than normal pressure to ensure positive flow from the reactor. The pressure of the inert gases must be high enough to overcome the pressure drop through the reactor.

The hydrocarbon concentration of the reactor feed stream is typically from about 1 mol% to about 10 mol%, preferably from about 1.5 mol% to about 5 mol%.

The temperature of the oxygen molecule or the gas containing the oxygen molecule mixed with the hydrocarbon is generally at least about 120 ° C, preferably in the range of about 120 ° C to about 200 ° C, and more preferably about 130 ° C to about 180 ° C. More preferably, it is the range of about 140-about 160 degreeC.

The hourly gas space velocity (“GHSV”) for the process is typically about 100 / hour to about 4000 / hour, preferably about 1000 / hour to about 3000 / hour, and more preferably about 1700 / hour to about 2500 Range of hours.

Catalysts suitable for use in the present invention are those well known in the art, and are generally materials capable of catalyzing maleic anhydride under vapor phase partial oxidation conditions of hydrocarbons having at least four linear carbon atoms. Examples of useful catalysts include vanadium-phosphor-oxide catalysts sold under the trade name E326 by Huntsman Corporation, activated according to the methods disclosed and claimed in US Pat. No. 5,137,860; Vanadium-phosphorus-oxide catalysts disclosed in US Pat. No. 4,632,915 or 4,670,415 and sold under the trade name E307 at Huntsman Corporation; And a modified vanadium-phosphorus-oxide catalyst sold under the trade name E326 by Huntsman Corporation, which is air fired and activated under nitrogen and steam; Andrews et al., US Pat. No. 5,275,996; Mitchell et al., US Pat. No. 5,641,722; And catalysts disclosed in US Pat. No. 5,773,382 (particularly those sold under the trade name E400 at Huntsman Corporation) and US patent application Ser. No. 08 / 538,005 filed on Feb. 20, 1995; Catalysts disclosed in US patent application Ser. No. 08 / 909,638, filed on Aug. 1997, in particular those sold under the trade name E358 at Huntsman Corporation. However, it is to be understood that these examples are not intended to limit the invention, but are for the purpose of illustrating and guiding the practice of the invention. The atomic ratio of vanadium to phosphorus in these catalysts may range from about 0.5: 1 to about 1.25: 1, preferably from about 0.95: 1 to about 1.2: 1. Among these catalysts, preferably the catalysts include those sold under the trade names E400 and E358 at Huntsman Corporation.

In the process of the invention, the catalyst can be used in one or more fixed beds. The size and shape of this fixed bed is not very important. By way of example, the catalyst may be a solid or hollow cylinder, or may be in another suitable form.

Phosphorus-containing materials suitable for use in the present invention are those well known in the art and are generally materials that can improve the control of catalytic activity and / or selectivity of the catalyst when included in the reactor feed stream. Non-limiting examples of useful catalysts are disclosed in US Pat. No. 4,701,433, but these are also for the purpose of describing and guiding the practice of the present invention, but not for limitation.

Among such phosphorus-containing materials, preferred for use according to the present invention include alkyl esters of orthophosphonic acid or alkyl esters of orthophosphonic acid derivatives. Preferably, the phosphorus containing material is an alkylester of orthophosphonic acid having the structure:

(RO) ₃ P = O (I)

Or an alkyl ester of an orthophosphonic acid derivative having the structure

(RO) ₃ P (II)

Wherein R is hydrogen or alkyl of C ₁ -C ₄ , at least one R is R of C ₁ -C ₄ . More preferably, the phosphorus containing material comprises a compound selected from the group comprising trialkyl phosphates and trialkyl phosphites. More preferably, the phosphorus containing material comprises a compound selected from the group comprising trimethyl phosphate, triethyl phosphate, trimethyl phosphite and triethyl phosphite. More preferably, the phosphorus containing material is trimethyl phosphate.

The phosphorus containing material concentration in the reactor feed stream is preferably at least about 1 ppmw, preferably between about 1 ppmw and about 20 ppmw, more preferably between about 4 ppmw and about 17 ppmw, and even more preferably between about 7 ppmw and about 14 ppmw. Introduction of the phosphorus containing material may be continuous or intermittent, preferably continuous. The rate at which phosphorus containing material is introduced into the catalytic reactor generally ranges from about 0.005 g / kg total bed catalyst / day to 5 g / kg total bed catalyst / day.

Most of the hydrocarbons having 4 to 10 carbon atoms can be converted to maleic anhydride in the process of the present invention. Only hydrocarbons having at least four linear carbon atoms are required. As an example, saturated hydrocarbon n-butane is suitable, but isobutane (2-methyl propane), although present in the process, does no harm, but is not suitable for conversion to maleic anhydride. In addition to n-butane, other suitable saturated hydrocarbons may be pentanes, hexanes, heptanes, n-butanes or no n-butanes, as long as they are present in saturated hydrocarbon molecules with at least four straight chain carbon atoms. Octanes, nonanes, decanes, and any mixture thereof.

Unsaturated hydrocarbons are also suitable for conversion to maleic anhydride according to the process of the invention. Suitable unsaturated hydrocarbons include butenes (1-butene and 2-butene), 1,3-butadiene, pentene, hexene, as long as the conditions exist in the molecule of a hydrocarbon chain having at least four linear carbon atoms Heptenes, octenes, nonenes, dekenes, and certain mixtures thereof.

Ring compounds such as cyclopentane and cyclopentene are also suitable as feed materials for conversion to maleic anhydride.

Of the aforementioned feedstocks, n-butane is the preferred saturated hydrocarbon, butenes are the preferred unsaturated hydrocarbons, and more preferably used with n-butane. The above mentioned feedstocks need not necessarily be pure materials but can be industrial grade hydrocarbons.

Small amounts of methyl maleic anhydride may be produced if the feedstock is a hydrocarbon comprising more than 4 carbons, but the main product resulting from the oxidation of suitable feedstocks mentioned above is maleic anhydride. Maleic anhydride prepared according to the process of the invention can be recovered by any method known to those skilled in the art. As an example, maleic anhydride may be recovered by direct concentration or by adsorption in a suitable medium with continued separation or purification of the anhydride.

Typical average values of the conversion of hydrocarbons to the reactor are at least about 60%, preferably about 60% to about 90%, more preferably about 70% to about 85%, more preferably about 80% to About 85%.

Typical average values for the yield of the first maleic anhydride produced are at least about 40 mole percent, preferably at least about 45 mole percent, and more preferably at least about 47 mole percent.

In general, the improved method exhibits an average yield reduction of less than about 0.25% / month, preferably less than about 0.15%, and more preferably less than about 0.125%.

The invention is illustrated by the following examples, which are intended to illustrate the invention only, and are not to be considered as limiting the scope or practice of the invention.

Example 1 Reduction of Trimethyl Phosphate Deposits

The multi-tubular fixed catalyst bed reactor was operated to produce maleic anhydride from a reactor feed stream comprising n-butane in air. The reactor tubes were filled with in-vanadium catalyst. The reactor was operated under the following conditions: The space velocity of the reactor was from about 1000 / hour to about 3000 / hour. N-butane concentration in the reactor feed stream was maintained at 1.5 mol% to about 5.0 mol%; Reactor temperature was maintained between about 325 ° C. and about 500 ° C .; Reactor pressure was maintained between about 18 psig and about 28 psig. Liquid trimethyl phosphate was injected into the 3 inch n-butane feed line before mixing the n-butane with air to form the reactor feed stream to control the reactor temperature. Trimethyl phosphate concentration in the reactor feed stream was maintained between about 1 ppmw and about 20 ppmw. Prior to introduction into the reactor, the total residence time of trimethyl phosphate in the n-butane feed line and in the reactor feed stream was less than 1 second.

After 24 months of operation, the reactor was shut down. Observation of the reactor visually revealed very thick deposits of trimethyl phosphate or trimethyl phosphate degradation products in the reactor inlet head and piping. The reactor was run for another nine months again at substantially the same conditions as described above. At the end of nine months, the reactor was stopped, cleaned and refilled with a phosphorus-vanadium catalyst.

The refilled reactor was run for an additional 18 months under substantially the same conditions as described above. At the end of 18 months, the reactor was stopped. Visual observation of the reactor revealed relatively less thick trimethyl phosphate or trimethyl phosphate degradation products deposited on the reactor inlet head, tubing and rupture plate housing. The reactor was run again.

After about two months, the method used to introduce trimethyl phosphate into the reactor was modified. The inlet for adding trimethyl phosphate to the n-butane feed line was moved upstream to allow the first amount of trimethyl phosphate to pass through the internal butane filter. This arrangement was operated as a trimethyl phosphate vaporization means by increasing the surface area for the impact of the unvaporized trimethyl phosphate droplets. 6-inch butane feed line with trimethyl phosphate introduced through a sintered metal tip welded into a 1 / 2-inch tube and a gland designed for removal and insertion without interrupting the 1-inch ball valve and butane flow Inserted into A second (less) amount of trimethyl phosphate was introduced downstream of the butane filter to further control the trimethyl phosphate concentration of the reactor feed stream introduced into the reactor. The trimethyl phosphate inlet was placed more upstream and the first amount of trimethyl phosphate was passed through a butane filter to increase the time for which the first trimethyl phosphate stays in the feed lines before introduction into the reactor from about 8 seconds to about 13 seconds.

After installation of the modified trimethyl phosphate injection system, the reactor was run for an additional six months at substantially the same conditions as described above. At the end of 6 months, the reactor was shut down. Visual observation of the reactor revealed that the reactor inlet head, tubing and rupture plate housings were substantially dry and no trimethyl phosphate or trimethyl phosphate by-products were present. Indeed, a decrease in sediment appeared to have occurred compared to previous observations.

Example 2: Reduction of Trimethyl Phosphate Deposits

A second multi-tube fixed catalyst bed reactor similar to the reactor of Example 1 was cleaned and refilled with the in-vanadium catalyst. Prior to running the reactor again, the trimethyl phosphate injection system was modified in the same manner as provided in Example 1. The reactor was then run for 18 months under conditions substantially similar to those described in Example 1. At the end of 18 months, the reactor was stopped. Visual observation of the reactor revealed that the reactor inlet heads, tubing and rupture plate housings were substantially dry and no trimethyl phosphate or trimethyl phosphate by-products were present.

Example 3: Reduction of Trimethyl Phosphate Concentration Variability in a Feed Stream

In a system comprising the reactor of Example 1, the trimethyl phosphate concentration in the reactor feed stream introduced into the reactor was determined and measured by on-line monitoring of the total flow rate of the reactor stream and the trimethyl phosphate feed stream. Mass balance calculation was performed using the flow value. The concentration of trimethyl phosphate in the reactor feed stream was maintained in the range of about 1 ppmw to about 20 ppmw. Prior to applying a modified trimethyl phosphate injection system as described in Example 1, a trimethyl phosphate feed tank pressurized with nitrogen was used to regulate the flow of trimethyl phosphate from the feed tank into the n-butane feed line. After introducing the modified trimethyl phosphate injection system, the flow of trimethyl phosphate was regulated from the feed tank into the n-butane feedline using a metering pump instead of using nitrogen pressure as the power for control of the flow.

In general, during the measurement, the standard deviation of trimethyl phosphate concentration in the reactor feed stream was reduced from 1.1 ppm to 0.3 ppm after conversion to the metering pump. When using a feed tank pressurized with nitrogen, the trimethyl phosphate level in the liquid phase in the feed tank affected the flow of trimethyl phosphate from the tank. Switching to the metering pump usually eliminated this change.

FIG. 4 illustrates the standard deviation of trimethyl phosphate concentration in a reactor feed stream where addition is performed using (1) a pressurized trimethyl phosphate feed tank and (2) a metering pump. The saw blade line at the top of FIG. 4 shows the trimethyl phosphate concentration over time in the trimethyl phosphate feed tank. The line at the bottom of FIG. 4 shows the change in the corresponding trimethyl phosphate concentration in the reactor feed stream. The left part of this line corresponds to the change in trimethyl phosphate concentration in the reactor feed stream where addition is carried out using a nitrogen pressurized trimethyl phosphate feed tank. The right part of this line corresponds to the change in trimethyl phosphate concentration in the reactor feed stream where addition is carried out using a metering pump. As shown in FIG. 1, the change in trimethyl phosphate concentration was reduced by about 70% after conversion to the metering pump. The overall average of trimethyl phosphate concentrations in the feed stream is substantially the same for both addition methods, but using a metering pump to reduce the change in concentration improved the ability to analyze and control other operating variables.

Thus, it will be apparent that the method provided according to the invention can fully satisfy the objects and advantages of the invention described above. While the present invention has been described in connection with various embodiments thereof, it will be apparent to those skilled in the art that the present invention is not limited thereto, and that various alternatives, modifications, and variations are possible. All citations recorded in this application are incorporated herein by reference.

When introducing the components of the present invention or preferred embodiment (s), the articles “a”, “an”, “the”, and “said” are one or more. Used to mean components. The expressions "comprising", "including" and "having" are inclusive and are used with the intention to mean that there may be additional components other than the listed components.

Claims (146)

delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete In a catalytic reactor comprising a fixed catalyst bed having an active site comprising a vanadium-phosphorus-oxygen catalyst for the catalytic oxidation of hydrocarbons to maleic anhydride, hydrocarbons having at least four linear carbon atoms are reacted with oxygen molecules. A method for producing maleic anhydride by the step of producing a maleic anhydride by continuously or intermittently introducing the phosphorous-containing material into the reactor, introducing the phosphorous-containing material into the reactor to improve the distribution of the phosphorous-containing material in the entire reactor As a way to improve the way Providing a phosphorus-bearing hydrocarbon feed stream by introducing phosphorus containing material into a gaseous feed stream comprising hydrocarbons, Combining the phosphorus carrier hydrocarbon feed stream with an oxygen molecule or a gas comprising an oxygen molecule to produce a reactor feed stream, and Reacting the hydrocarbons with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride, A process for producing maleic anhydride characterized by controlling the introduction of phosphorus containing material into a hydrocarbon feed stream such that the phosphorous containing material is uniformly distributed throughout the reactor feed stream before the reactor feed stream enters the catalyst bed. 81. The method of claim 80, wherein the introduction of the phosphorus containing material into the hydrocarbon feed stream is controlled such that at least 90% of the phosphorus containing material vaporizes before the reactor feed stream enters the catalyst bed. 81. The method of claim 80, wherein said phosphorous containing material is a liquid. 81. The method of claim 80, wherein prior to combining the phosphorus carrier hydrocarbon feed stream with an oxygen molecule or a gas comprising oxygen molecules, the residence time of the phosphorus containing material in the phosphorus carrier hydrocarbon feed stream is greater than 1 second. Controlling the introduction into the hydrocarbon feed stream. The method of claim 80, Providing a phosphorus carrier hydrocarbon feed stream by introducing a liquid phosphorus containing material into a gaseous feed stream comprising hydrocarbons in a first mixing zone upstream of the filter medium through which the hydrocarbon feed stream passes; Combining the phosphorus carrier hydrocarbon feed stream with an oxygen molecule or a gas comprising an oxygen molecule downstream of the oxygen mixing zone of the filter medium to produce a reactor feed stream; And Reacting the hydrocarbons with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride, And the residence time of the phosphorus carrier hydrocarbon feed stream between the first and oxygen mixing zones is greater than one second. 85. The method of claim 83 or 84, wherein the residence time is greater than 3 seconds. 85. The method of claim 83 or 84, wherein the residence time is between 8 and 15 seconds. 85. The method of claim 84, wherein the filter medium serves to reduce the particle size of the liquid phosphorus containing material and to promote uniform distribution of the phosphorus containing material in the phosphorus carrier hydrocarbon feed stream. 85. The process of claim 84, wherein the average particle size of the phosphorous containing material in the reactor feed stream is less than 10 microns. 85. The process of claim 84, wherein the average particle size of the phosphorus containing material in the reactor feed stream is less than 3 microns. 85. The method of claim 84, wherein the phosphorous containing material is preheated to a temperature below the temperature of the hydrocarbon feed stream, above 20 ° C, before it is introduced into the hydrocarbon feed stream. 85. The method of claim 84, wherein the phosphorous containing material is preheated to a temperature below the temperature of the hydrocarbon feed stream, up to a temperature higher than 10 ° C, prior to introduction into the hydrocarbon feed stream. 85. The method of claim 84, wherein the phosphorous containing material is preheated to a temperature of at least 70 ° C prior to introduction into the hydrocarbon feed stream. 85. The method of claim 84, wherein the phosphorous containing material is injected into the hydrocarbon feed stream. 85. The phosphorous containing material of claim 84, wherein the phosphorous containing material is introduced into the hydrocarbon feedstream through a tube inserted into the hydrocarbon feedstream, the tube having a fritted tip through which the phosphorus containing material exits the tube. Method comprising a. 95. The method of claim 94, wherein the tube is inserted into the hydrocarbon feed stream perpendicular to the flow direction of the hydrocarbon feed stream. 85. The process of claim 84, wherein the phosphorus carrier hydrocarbon feed stream is divided into two or more separate feed streams for use in two or more separate catalytic reactors. 85. The method of claim 84, wherein the method introduces phosphorous containing material at a first rate into the hydrocarbon feed stream to form a phosphorus carrier hydrocarbon feed stream and downstream from the position at which the phosphorous containing material is introduced into the hydrocarbon feed stream. Phosphorus transporting a hydrocarbon feed stream further comprising introducing additional phosphorus containing material at a second rate. 87. The method of claim 84, wherein the method further comprises introducing additional phosphorus containing material from the filter medium into the downstream phosphorus carrier hydrocarbon feed stream. 85. The method of claim 84, wherein the phosphorous containing material comprises an alkyl ester of orthophosphonic acid or an alkyl ester of orthophosphonic acid derivative. 85. The composition of claim 84, wherein the phosphorus containing material is an alkyl ester of orthophosphonic acid having the structure: (RO) ₃ P = O (I) Or an alkyl ester of an orthophosphonic acid derivative having the structure (RO) ₃ P (II) Wherein R is hydrogen or alkyl of C ₁ to C ₄ and at least one R is alkyl of C ₁ to C ₄ . 101. The method of claim 100, wherein the phosphorous containing material is selected from the group comprising trialkyl phosphate and trialkyl phosphite. 102. The method of claim 101, wherein the phosphorous containing material is selected from the group comprising trimethyl phosphate, triethyl phosphate, trimethyl phosphite and triethyl phosphite. 103. The method of claim 102, wherein the phosphorous containing material is trimethyl phosphate. 85. The process of claim 84, wherein the concentration of phosphorus containing material in the reactor feed stream is between 1 ppmw and 20 ppmw. 85. The process of claim 84, wherein the concentration of phosphorus containing material in the reactor feed stream is between 7ppmw and 14ppmw. 85. The process of claim 84, wherein the rate at which phosphorus containing material is introduced into the catalytic reactor is 0.005-5 g / kg total bed catalyst / day. 85. The method of claim 84, wherein the catalyst has a ratio of phosphorus / vanadium atoms of 0.95 to 1.2. 85. The method of claim 84, wherein the hydrocarbon is a saturated hydrocarbon. 109. The method of claim 108, wherein the hydrocarbon is n-butane. 85. The method of claim 84, wherein the gas comprising oxygen molecules is air. 85. The method of claim 84, wherein the hydrocarbon concentration in air is 1-10 mole percent. 85. The process of claim 84, wherein the hydrocarbon concentration in air is 1.5-4 mol%. 85. The method of claim 84, wherein the reaction proceeds at a temperature of 300 to 600 [deg.] C., a pressure of 14.7 to 50.0 psig, and a space velocity of 100 to 4000 / hour. 85. The method of claim 84, wherein the reaction proceeds at a temperature of 425-450 [deg.] C., a pressure of 20.0-28.0 psig, and a space velocity of 1700-2500 / hour. 85. The process of claim 84, wherein the conversion of hydrocarbons introduced into the reactor is at least 70%. 85. The method of claim 84, wherein the yield of maleic anhydride is at least 45 mole percent. 85. The method of claim 84, wherein the method exhibits an average yield reduction of less than 0.25% / month. The method of claim 80, Providing a phosphorus carrier hydrocarbon feed stream by introducing a liquid phosphorus containing material into a gaseous feed stream comprising hydrocarbons in a first mixing zone upstream of the gas / liquid contact zone, wherein the gas / liquid contact zone is liquid phosphorus Means for promoting interfacial contact between the containing material and the hydrocarbon feed gas; Combining the phosphorus carrier hydrocarbon feed stream with an oxygen molecule or gas comprising an oxygen molecule downstream of the gas / liquid contacting zone to produce a reactor feed stream; And, Reacting the hydrocarbon with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride. 118. The method of claim 118, wherein the hydrocarbon feed stream comprises droplets of liquid phosphorus containing material, and wherein the means serves to reduce the size of the droplets by providing a surface area for collision of the droplets. . 118. The method of claim 118, wherein the means comprises means selected from the group comprising filter media, static mixers, pipe piping and turbulent induction flow devices. 126. The method of claim 120, wherein said means comprises a filter medium. 126. The method of claim 121, wherein the means comprises a filter medium and serves to promote a reduction in particle size of the phosphorus containing material and a uniform distribution of the phosphorus containing material in the phosphorus carrier hydrocarbon feed stream. The method of claim 80, Providing a phosphorus carrier hydrocarbon feed stream by introducing a liquid phosphorus containing material into a gaseous feed stream comprising hydrocarbons in a first mixing zone; By passing the phosphorus feed feed stream through a filter medium which blocks the liquid phosphorus containing material and distributes it in a medium that laterally crosses the flow path of the hydrocarbon feed stream, the liquid is re-captured back into the filter medium. Dispersing the phosphorus-containing material to promote uniform radial distribution of the phosphorus-containing material into the phosphorus carrier hydrocarbon stream; Combining the phosphorus containing hydrocarbon feed stream with an oxygen molecule or a gas comprising an oxygen molecule in an oxygen mixing zone downstream of the filter medium; And Reacting the hydrocarbons with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride. 124. The method of claim 123, wherein the liquid phosphorus-containing material is trapped in droplets that provide a high surface area effective for promoting vaporization of the phosphorus-containing material in the gas stream when mixed with the oxygen-containing gas. 127. The method of claim 124, wherein the droplets have a particle size of 1 to 5 microns. 126. The method of claim 125, wherein the filter medium comprises a porous medium having an average pore size of 1 to 5 microns. 126. The method of claim 123, wherein the filter medium extends substantially across the entire flow path of the phosphorus carrier hydrocarbon feed stream. The method of claim 80, Providing a phosphorus carrier hydrocarbon feed stream by introducing the phosphorus containing material into a gaseous feed stream comprising hydrocarbons in a first mixing zone; Passing the phosphorus feed feed stream through a conduit comprising a flow restriction including means for dispersing the phosphorus containing material to facilitate uniform radial dispersion of the phosphorous containing material within the phosphorus carrier hydrocarbon stream. step; Combining the phosphorus carrier hydrocarbon feed stream with an oxygen molecule or a gas comprising an oxygen molecule in an oxygen mixing zone downstream of the flow restriction comprising means for dispersing the phosphorus containing material; And Reacting the hydrocarbons with oxygen molecules in a reactor to produce a reaction product comprising maleic anhydride. 129. The method of claim 128, wherein said phosphorous containing material comprises a liquid and said flow restriction comprises a gas / liquid contact region comprising means effective to promote interfacial contact between a liquid phosphorous containing material and a hydrocarbon gas. How to feature. 129. The method of claim 129, wherein passing the phosphorus carrier hydrocarbon feed stream through the gas / liquid contacting zone is effective to reduce the average particle size of droplets of phosphorus containing material dispersed in gaseous hydrocarbons. 131. The method of claim 130, wherein the average particle size of the droplets is reduced to a size effective to promote vaporization of the phosphorous containing material after the phosphorus carrier hydrocarbon stream is mixed with the oxygen containing gas. 134. The method of claim 131, wherein the gas / liquid contact area comprises means for promoting vaporization of the impingement surface and / or droplets for the droplets. 129. The method of claim 128, wherein the flow restriction is selected from the group comprising filter media, static mixers, piping, and turbulent induction flow devices. The method of claim 80, Providing a first phosphorus carrier hydrocarbon feed stream by introducing phosphorus containing material into a feed stream comprising hydrocarbons in a first mixing zone at a first rate; Directing the first phosphorus carrier hydrocarbon feed stream through a first conduit to a second mixing zone; Providing a second phosphorus carrier hydrocarbon feed stream by introducing additional phosphorus containing material into the first phosphorus carrier hydrocarbon feed stream in a second mixing zone at a second rate; Directing a second phosphorus carrier hydrocarbon feed stream through a second conduit to an oxygen mixing zone to mix the phosphorus carrier hydrocarbon feed stream with an oxygen molecule or a gas comprising oxygen molecules in an oxygen mixing zone to form a reactor feed stream, wherein The sum of the residence time of the first phosphorus carrier hydrocarbon feed stream between the first and second mixing zones and the residence time between the second and oxygen mixing zones of the second phosphorus carrier hydrocarbon feed stream is greater than 1 second; Reacting the hydrocarbon with an oxygen molecule in a reactor to produce a reaction product comprising maleic anhydride. 137. The method of claim 97 or 134, wherein the ratio of first speed to second speed is at least 3: 1. 137. The method of claim 97 or 134, wherein the ratio of first speed to second speed is at least 4: 1. The method of claim 80, Dividing the supply of phosphorus containing material into a first feed for delivering to the first mixing zone and a second feed for delivering a flow of hydrocarbon gas to the reactor downstream of the first mixing zone; Measuring the flow rate of hydrocarbon gas entering the first mixing zone; Controlling the rate of said first feed of phosphorus containing material introduced into said first mixing zone to provide a predetermined minimum concentration of said phosphorus containing material present in said first phosphorus carrier hydrocarbon stream exiting said first mixing zone. ; Introducing the second feed of phosphorus containing material and the first phosphorus carrier hydrocarbon stream into the second mixing zone to produce a regulated phosphorus carrier hydrocarbon stream; And Mixing the regulated phosphorus carrier hydrocarbon feed stream with an oxygen containing gas to produce the reactor feed stream, A predetermined concentration having a ratio of hydrocarbon to phosphorus containing compound effective to provide a target concentration of phosphorus in the reactor feed gas entering the catalyst bed, wherein the total concentration of phosphorus containing material in the regulated phosphorus carrier hydrocarbon stream is And controlling a second feed rate of the phosphorous containing material into the second mixing zone to correspond to 139. The second supply of phosphorus carrier hydrocarbon stream and the phosphorus containing material exiting the first mixing zone is a plurality of second for separate supply to a plurality of second mixing zones downstream of the first mixing zone. Wherein the regulated phosphorus carrier hydrocarbon feed stream, each divided into a stream and withdrawn from each second mixing zone, is delivered to the reactor among a plurality of reactors, each fed from a separate second mixing zone. 138. The method of claim 138, wherein the concentration of phosphorus-containing material in the phosphorus carrier hydrocarbon stream exiting the first mixing zone provides a minimum of the target concentration of phosphorus in the reactor feed gas that each enters the catalyst beds of the plurality of reactors. Characterized by being equal to or lower than a predetermined concentration having a ratio of hydrocarbon to phosphorus containing compound. 139. The method of claim 139, wherein the rate at which each phosphorus containing compound is introduced into the plurality of second mixing zones is effective to provide a target concentration of phosphorus in the reactor feed gas entering the catalyst bed to which the stream exiting the second mixing zone is directed. And controlled to provide a predetermined concentration having a ratio of phosphorus containing compound to hydrocarbon. 138. The method of claim 137, Introducing a second feed of the phosphorus containing material and another stream comprising the first phosphorus carrier hydrocarbon stream into the second mixing zone to produce a regulated phosphorus carrier hydrocarbon stream, A predetermined concentration having a ratio of phosphorus containing compound to hydrocarbon that is effective to provide a target concentration of phosphorus in the reactor feed gas entering the catalyst bed in the total concentration of phosphorus containing material in the regulated phosphorus carrier hydrocarbon stream Controlling the rate at which the second supply of phosphorus containing material is introduced into the second mixing zone to correspond to 143. The process of claim 141, wherein the first phosphorus carrier hydrocarbon stream is mixed with phosphorus containing material introduced into the second mixing zone. 143. The method of claim 141, wherein the first phosphorus carrier hydrocarbon stream is mixed with an oxygen containing gas to produce a preconditioned reactor feed gas; And said preconditioned reactor feed gas is mixed with phosphorus containing material introduced into said second mixing zone to produce a regulated reactor feed stream. 81. The method of claim 80, wherein the plurality of catalytic reactors are used, Measuring the flow rate of the feed stream comprising hydrocarbon; Calculating a first rate of addition of the phosphorus containing material to be introduced to the hydrocarbon feed stream; Controlling the introduction of phosphorus-containing material into the hydrocarbon feed stream according to the calculated first addition rate, wherein the phosphorus-containing material is introduced into the hydrocarbon feed stream in the first mixing zone so that the first phosphorus carrier hydrocarbon feed stream is Wherein the first phosphorus carrier hydrocarbon feed stream passes through a first conduit and is divided into a plurality of second hydrocarbon feed streams through which the first phosphorus carrier hydrocarbon feed stream is passed through a series of second conduits to a series of second mixing zones. Flow into the manifolds; Calculating a second rate of addition of phosphorus containing material that is selectively introduced into each second hydrocarbon feed stream; Controlling the introduction of phosphorus containing material into each second hydrocarbon feed stream according to each calculated second addition rate, wherein the phosphorous containing material is introduced into each second hydrocarbon feed stream in each second mixing zone. Optionally introduced to provide a plurality of second phosphorus carrier hydrocarbon feed streams, and the second rate of addition of the phosphorus containing material introduced to each second hydrocarbon feed stream is introduced into each other second hydrocarbon feed stream. Independent of the second rate of addition of the phosphorus containing material; Mixing each second phosphorus carrier hydrocarbon feed stream with an oxygen molecule or a gas comprising an oxygen molecule in an oxygen mixing zone, thereby producing a plurality of second reactor feed streams introduced into the separated catalytic reactors, the first mixing Residence time of the first phosphorus carrier hydrocarbon feed stream between the zone and the branch pipe, residence time of the second hydrocarbon feed stream between the branch pipe and the second mixing zone and second phosphorus carrier hydrocarbon feed stream between the second mixing zone and the oxygen mixing zone. The sum of the residence times of is greater than 1 second; And Reacting the hydrocarbon with an oxygen molecule in each catalytic reactor to produce a reaction product comprising maleic anhydride, The first addition rate corresponds to a predetermined minimum addition rate of phosphorus containing material as a function of the measured flow rate of the hydrocarbon feed stream, The second addition rate is calculated independently for each second hydrocarbon feed stream as a function of the measured flow rate of the hydrocarbon feed stream, which means that a second reactor feed stream is included in the first mixing zone that is included in the second reactor feed stream. Characterized in that it corresponds to the final target rate of addition of the phosphorus-containing material to the reactor which is reduced by a fraction of the phosphorus-containing material already introduced. The method of claim 80, Measuring the flow rate of the feed stream comprising hydrocarbon; Calculating a first rate of addition of the phosphorus containing material to be introduced to the hydrocarbon feed stream; Controlling the introduction of phosphorus containing material into the hydrocarbon feed stream in accordance with the calculated first addition rate, wherein the phosphorous containing material is introduced into the hydrocarbon feed stream in the first mixing zone to provide the first phosphorus carrier hydrocarbon feed stream. And the first phosphorus carrier hydrocarbon feed stream passes through the first conduit to the second mixing zone; Calculating a second rate of addition of phosphorus containing material to be selectively introduced into the first phosphorus carrier hydrocarbon feed stream; Controlling the introduction of phosphorus-containing material into the first phosphorus carrier hydrocarbon feed stream according to the calculated addition rate, wherein the phosphorus-containing material is introduced into the first phosphorus carrier hydrocarbon feed stream in a second mixing zone to provide a second phosphorus carrier hydrocarbon feed. Provide a stream; Combining a second phosphorus carrier hydrocarbon feed stream in the oxygen mixing zone with an oxygen molecule or a gas comprising an oxygen molecule to form a reactor feed stream, wherein the first phosphorus carrier hydrocarbon feed stream between the first mixing zone and the second mixing zone is The sum of the residence time and the residence time of the second phosphorus carrier hydrocarbon feed stream between the second and oxygen mixing zones is greater than 1 second; And, Reacting the hydrocarbon with an oxygen molecule in a reactor to produce a reaction product comprising maleic anhydride, Said first addition rate corresponds to a predetermined minimum addition rate of phosphorus containing material as a function of the measured flow rate of the hydrocarbon feed stream, The second addition rate is calculated as a function of the measured flow rate of the hydrocarbon feed stream, which is reduced by the phosphorus containing material already introduced into the first mixing zone to correspond to the final target rate of phosphorus containing material added to the reactor. How to feature. 145. The method of claim 145, wherein the introduction of phosphorus-containing material in the first and second mixing zones is controlled by one or more PID controllers.

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