KR100628675B1 - Process for the production of vinyl acetate - Google Patents

Abstract

The present invention contacts a gaseous feedstock comprising essentially ethane in a first reaction zone with a molecular oxygen containing gas in the presence of a catalyst to produce a first product stream comprising acetic acid and essentially ethane in a second reaction zone. Contacting a gaseous feedstock comprising molecular oxy-containing gas in the presence of a catalyst to produce a second product stream comprising ethylene, and in the third reaction zone the first gas product stream and the second gas product stream in the presence of a catalyst. Contacting with a molecular oxygen containing gas to produce a third product stream comprising vinyl acetate, separating the product stream from step (3), and recovering vinyl acetate from the product stream from step (3). will be.

Ethane, molecular oxygen-containing gas, vinyl acetate, catalyst.

Description

Process for the production of vinyl acetate

The present invention generally relates to an integrated process for the production of vinyl acetate, in particular a process for the integrated production of vinyl acetate from a gaseous feedstock comprising essentially ethane.

Vinyl acetate is generally produced commercially by contacting acetic acid and ethylene with molecular oxygen in the presence of an active catalyst for the production of vinyl acetate. Suitably the catalyst may comprise palladium, alkali metal acetate promoters and any co-promoter (eg gold or cadmium) on the catalyst support. Since iodide is recognized as a potential vinyl acetate catalysis poisoner, acetic acid, usually produced by carbonylation, needs to be extensively purified to remove special iodides from commonly used catalyst systems. There is.

Combinations of methods of making vinyl acetate are known in the art. Accordingly, WO 98/05620 discloses contacting ethylene and / or ethane with oxygen in a first reaction zone to produce a first product stream comprising acetic acid, water and ethylene, in a second reaction zone. Contacting the first product stream with oxygen in the presence or absence of additional ethylene and / or acetic acid to produce a second product stream comprising vinyl acetate, water, acetic acid and any ethylene, the product stream from the second step Distilling to separate the upper azeotrope fraction containing vinyl acetate and water and the lower fraction containing acetic acid, recovering acetic acid from the lower fraction and optionally refluxing the azeotrope fraction, or recovering vinyl acetate from the azeotrope fraction. Method for producing vinyl acetate and / or acetic acid comprising the step It is material. The catalyst proposed in WO98 / 05620 for oxidizing ethylene with acetic acid or ethane with acetic acid is a catalyst of formula (I).

Pd _a M _b TiP _c O _x

In the above formula,

M is selected from Cd, Au, Zn, Tl, alkali metals and alkaline earth metals.

Another catalyst for oxidizing ethane to acetic acid is a catalyst of formula (II).

VP _a M _b O _x

In the above formula,

M is from Co, Cu, Re, Fe, Ni, Nb, Cr, W, U, Ta, Ti, Zr, Zn, Hf, Mn, Pt, Pd, Sn, Sb, Bi, Ce, As, Ag and Au Selected,

The catalyst is a catalyst for oxidizing ethane and / or ethylene to produce ethylene and / or acetic acid, the catalyst comprising A, X and Y elements, where A is Mo _d Re _e W _f , X is Cr, Mn, Nb, Ta, V or W and Y is Bi, Ce, Co, Cu, Fe, K, Mg, Ni, P, Pb, Sb, Si, Sn, Tl or U.

Another catalyst for oxidizing ethane described in WO 98/05620 to acetic acid and ethylene is the catalyst of formula III.

Mo _x V _y Z _z

In the above formula,

Z is Li, Na, Be, Mg, Ca, Sr, Ba, Zn, Cd, Hg, Sc, Y, La, Ce, Al, Tl, Ti, Zr, Hf, Pb, Nb, Ta, As, Sb, Bi, Cr, W, U, Te, Fe, Co and Ni.

US Pat. No. 5,185,308, cited in WO98 / 05620, describes an example of obtaining a space time yield in the range of 555 to 993 g of vinyl acetate per hour per liter of unit catalyst.

It is an object of the present invention to provide an integrated process for producing vinyl acetate from a gaseous feedstock comprising essentially ethane as the only external carbon source of the feedstock, wherein the space / hour yield of the process is 100 vinyl acetate per hour per unit catalyst. To 2000 g, preferably 500 to 1500 g of vinyl acetate per hour per liter of unit catalyst.

Therefore, the present invention

Contacting a gaseous feedstock comprising essentially ethane in a first reaction zone with a molecular oxygen containing gas in the presence of a catalyst to produce a first product stream comprising acetic acid,

Contacting a gaseous feedstock comprising essentially ethane in a second reaction zone with a molecular oxygen containing gas in the presence of a catalyst to produce a second product stream comprising ethylene,

Contacting the first gas product stream and the second gas product stream with a molecular oxygen containing gas in the presence of a catalyst in the presence or absence of additional ethylene or acetic acid in the third reaction zone to produce a third product stream comprising vinyl acetate. Step (3) and

An integrated process for the production of vinyl acetate is provided, comprising separating the product stream from step (3) and recovering vinyl acetate from the product stream from step (3).

The process according to the invention is based on the discovery that certain classes of catalysts can convert ethane to acetic acid or ethylene with very high selectivity and very high space time yields. This separated ethylene and acetic acid product stream can be mixed in an appropriate proportion and can be fed directly to the reactor to produce vinyl acetate.

The use of ethane instead of ethylene as feedstock has the advantage of using natural gas. In the natural gas operation process, a mixture comprising several ethanes is obtained, usually this mixture is simply combusted, but the whole can be used as a carbon feedstock for carrying out the process of the invention.

The particular advantages of the integrated process for the production of vinyl acetate of the present invention can primarily combine tissue, usability and other features, e.g. only a single feed gas compressor and an exhaust removal scrubbing system are required, while The acetic acid and vinyl acetate processes each require their own feed gas compressor and exhaust gas scrubbing system.

By combining the steps (1), (2) and (3) of the present invention, intermediate storage requirements are reduced compared to two separate processes. All these advantages reduce capital and operating costs.

According to the present invention, a gaseous feedstock comprising essentially ethane is contacted with a molecular oxygen containing gas in the presence of an active catalyst used to oxidize ethane to acetic acid in the first reaction zone to produce a first reaction product stream comprising acetic acid. Create

Active catalysts used to oxidize ethane to acetic acid may include any suitable catalyst as described in German Patent Publication No. 197 45 902, incorporated herein by reference. These catalysts are compounds of formula IV.

Mo _a Pd _b X _c Y _d

In the above formula,

delete

X is selected from one or more elements from the group consisting of Cr, Mn, Nb, Ta, Ti, V, Te and W,

Y is B, Al, Ga, In, Pt, Zn, Cd, Bi, Ce, Co, Rh, Ir, Cu, Ag, Au, Fe, Ru, Os, K, Rb, Cs, Mg, Ca, Sr, Is selected from one or more elements from the group consisting of Ba, Nb, Zr, Hf, Ni, P, Pb, Sb, Si, Sn, Tl and U,

a, b, c and d are g atomic ratios, respectively

a is 1,

b is 0.0001 to 0.01, preferably 0.0001 to 0.005,

c is 0.4 to 1, preferably 0.5 to 0.8,

d is 0.005 to 1, preferably 0.01 to 0.3.

Preferred catalysts are those in which X is V and Y is Nb, Sb and Ca. Pd ratios above the g atom limit above are advantageous for forming carbon dioxide, and Pd ratios below the g atom limit above are advantageous for forming ethylene and subsequently acetic acid. Particularly preferred catalysts for the process according to the invention are Mo _1.00 Pd _0.00075 V _0.55 Nb _0.09 Sb _0.01 Ca _0.01 .

 In a second reaction zone spatially separated from the first reaction zone, a gaseous feedstock comprising essentially ethane is contacted with a molecular oxygen-containing gas in the presence of an active catalyst used to oxidize ethane to ethylene, thereby including ethylene. To produce a second product stream.

The active catalyst used to oxidize ethane to ethylene may comprise the same catalyst as described above for oxidizing ethane to acetic acid. The two methods differ in their reaction conditions, in particular the overall pressure, residence time and water content of the feed. Oxidation of ethane to acetic acid is more advantageous at higher overall pressures than oxidative dehydrogenation of ethane to ethylene. When steam is fed together with ethane and molecular oxygen containing gas, acetic acid formation is the preferred reaction product, while steam may optionally be used for oxidative dehydrogenation of ethane to ethylene, but is not absolutely necessary.

Preferred catalysts are those in which X is V and Y is Nb, Sb and Ca. Pd ratios above the g atom limit are advantageous for forming carbon dioxide, and Pd ratios below the g atom limit above are advantageous for forming ethylene. Particularly preferred catalysts for the process according to the invention are Mo _1.00 Pd _0.00075 V _0.55 Nb _0.09 Sb _0.01 Ca _0.01 .

Also useful catalysts for oxidative dehydrogenation of ethane to ethylene are described in Liu, Y .; Cong, P .; Doolen, RD; Turner, HW; Weinberg, H .; Second Int. Symposium on Deactivation and Testing of Catalysts Presented Before the Division of Petroleum Chemistry, Inc .; 219 ^th National Meeting, ACS, San Francisco, CA, March 26-31, 2000; 298-302 and V-Al, V-Nb-Al, Cr-Nb-Al, and Cr-Ta-Al based oxides.

In addition, some other patents describe more general oxidative dehydrogenation of paraffins. Three patents describing oxidative dehydrogenation of paraffins on Ni oxide based catalysts should be cited exemplarily herein. For example, US Pat. No. 4,751,342 describes the use of alkali doped Ni-P-Sn oxide catalysts, while British Patent No. 2 050 188 describes Ni-Pb catalysts and US Pat. 3,886,090 describes Ni-Mg oxide catalysts modified with several other elements.

The present invention provides a wide range from 0 to 95% by varying the reaction parameters such as the reaction temperature, total pressure, partial pressure of the reactants, residence time, etc. There is an advantage to change from.

The reaction in the first and second reaction zones is an appropriate proportion of the amount of acetic acid and ethylene formed in these reactions such that the mixed first and second product streams are fed directly to the third reaction zone to provide additional acetic acid or ethylene It is desirable to carry out so that vinyl acetate can be formed without the need for feeding.

The active catalyst used to oxidize ethane can be used with or without support. Examples of suitable supports include silica, diatomaceous earth, montmorillonite, alumina, silica alumina, zirconia, titania, silicon carbide, activated carbon and mixtures thereof. The active catalyst used to oxidize ethane can be used in the form of a fixed bed or a fluidized bed.

The molecular oxygen-containing gas used in all of the reaction zones may be air or a gas having a higher or lower molecular oxygen than air. Suitable gases can be, for example, oxygen diluted with a suitable diluent (eg nitrogen or carbon dioxide). Preferably, the molecular oxygen containing gas is fed independently from the ethane feedstock into the first and second reaction zones.

The ethane feedstock of the process of the present invention is substantially pure or other gas produced by natural gas separation, ie 90% by weight (PERP, see “Natural Gas Liquids Extraction 94/95 S4, P. 60 May be diluted slightly with ") or it may be a mixture comprising one or more nitrogen, carbon dioxide, hydrogen and low levels of C3 / C4 alkenes / alkanes. Catalyst poisons such as sulfur should be excluded. Likewise, it is advantageous to minimize the amount of acetylene. The amount of inert components is limited only by economic problems.

Step (1) of the process of the invention may suitably be carried out such that ethane, molecular oxygen-containing gas, vapor and (if necessary) further inert material pass through the catalyst. The amount of steam may suitably range from 0 to 50% by volume. The molar ratio of ethane to oxygen may suitably range from 1: 1 to 10: 1, preferably from 2: 1 to 8: 1.

Step (1) of the process of the invention may suitably be carried out at a temperature of 200 to 500 ° C, preferably 200 to 400 ° C.

Step (1) of the process of the invention may suitably be carried out at atmospheric or superatmospheric pressure, for example, in the range of 1 to 100 bar, preferably 1 to 50 bar.

Typically, the ethane conversion, which ranges from 10 to 100%, in particular from 10 to 40%, depends on the concept of the reactor of step (1), which can be a reactor cascade with a niche oxygen supply, This can be accomplished in step (1) of the method.

Typically, oxygen conversion in the range of 90 to 100% can be achieved in step (1) of the process of the invention.

In step (1) of the process of the invention, the catalyst suitably has a productivity in the range of 100 to 2000 g of acetic acid per hour per liter of unit catalyst, preferably in the range of 100 to 1500 g of acetic acid per hour per liter of catalyst ("space time yield" = STY). Has

Step (1) of the present invention can be carried out in a fixed bed reactor as well as in a fluidized bed reactor.

The gaseous product stream from step (1) comprises acetic acid and water and may comprise by-products such as ethane, ethylene, oxygen, nitrogen and carbon monoxide and carbon dioxide. Usually, carbon monoxide is not produced in step (1) or in very small amounts (less than 100 ppm). If carbon monoxide is produced in a large amount of 5% or less, then, if necessary, after step (1), carbon dioxide may be adsorbed or burned off, for example, by molecular oxygen-containing gas. Acetic acid is preferably present in the gas product stream of step (1) in an amount necessary for direct conversion to vinyl acetate using ethylene contained in a second product stream that can be bound to the first product stream.

Step (2) of the process of the invention may be suitably carried out such that ethane, molecular oxygen containing gas, vapor and (if necessary) further inert material pass through the catalyst. The amount of steam may suitably range from 0 to 50% by volume. The molar ratio of ethane and oxygen may suitably range from 1: 1 to 10: 1, preferably from 2: 1 to 8: 1.

Step (2) of the process of the invention is preferably carried out at a temperature of 200 to 500 ° C, preferably 200 to 400 ° C.

Step (2) of the process of the invention may suitably be carried out at atmospheric or superatmospheric pressure, for example, in the range of 1 to 50 bar, preferably 1 to 30 bar.

Typically, the ethane conversion, which ranges from 10 to 100%, in particular from 10 to 40%, depends on the reactor concept of step (2), which can be a reactor multistage with a niche oxygen supply, thus allowing for step 2 of the process of the invention. Can be achieved in

Typically, oxygen conversion in the range of 90 to 100% can be achieved in step (2) of the present invention.

In step (2) of the process of the invention, the catalyst suitably has a productivity (STY) in the range of 100 to 2000 g of ethylene per hour per liter of unit catalyst, preferably in the range of 100 to 1500 g of ethylene per hour per liter of unit catalyst.

Step (2) of the process of the invention can be carried out in a fixed bed reactor as well as in a fluid bed reactor.

The gaseous product stream from step (2) comprises ethylene and water, and by-products such as ethane, acetic acid, oxygen, nitrogen and carbon monoxide and carbon dioxide. Usually, carbon monoxide is not produced in step (2) or in very small amounts (less than 100 ppm). If a large amount of carbon monoxide of 5% or less is produced, after step (2), carbon dioxide may be adsorbed or burned off with molecular oxygen-containing gas, if necessary. Ethylene is preferably present in the gaseous product stream of step (2) in an amount necessary for direct conversion to acetic acid with acetic acid included in the first product stream capable of being bound to the second product stream.

The ratio of ethylene / acetic acid required to feed the vinyl acetate reactor (step (3)) of the present invention is determined by the reaction parameters of step (1) and / or step (2), e.g. reaction temperature, total pressure, per gas unit time. The space velocity, the partial pressure of each reactant can be changed or, in particular, the vapor partial pressure of the feed of step (1) can be adjusted to suitably adjust.

The gaseous product from step (1) and the gaseous product from step (2) are any further molecular oxygen containing gas, any further ethylene and any that can be preferably recovered in the separation of the vinyl acetate of step (4). With further acetic acid of may be fed directly into the third reaction zone of step (3).

  The active catalyst used to prepare vinyl acetate in step (3) of the process of the invention can be any suitable catalyst known in the art, for example, British Patent 1 559 540, US Patent 5,185,308 and International Patents. Catalysts as described in WO99 / 08791.

EP 0 330 853 describes a catalyst for the production of vinyl acetate impregnated throughout, including Pd, K, Mn and Cd, as an additional promoter instead of Au.

British Patent 1 559 540 describes active catalysts used to make vinyl acetate by reacting ethylene, acetic acid and oxygen, which catalyst essentially comprises

(1) a catalyst support having a particle diameter of 3 to 7 mm, a void volume of 0.2 to 1.5 ml / g, and a pH of 10 to 20 wt% of a water suspension of the catalyst support of 3.0 to 9.0,

(2) a palladium-gold alloy distributed in the surface layer of the catalyst support, a surface layer extending less than 0.5 mm from the surface of the support, palladium in the alloy in which an amount of 1.5 to 5.0 g per liter of catalyst is present and 0.5 to 2.25 g per liter of catalyst Gold and in the amount of

(3) 5 to 60 g per liter of alkali metal acetate catalyst.

U. S. Patent No. 5,185, 308 discloses an active catalyst impregnated with a shell used to make vinyl acetate from a gas comprising ethylene, acetic acid and oxygen, which essentially consists of:

(1) a catalyst support having a particle diameter of about 3 to about 7 mm and a pore volume of 0.2 to 1.5 ml / g,

(2) palladium and gold distributed in the outermost 1.0 mm thick layer of catalyst support particles;

(3) about 3.5 to about 9.5 weight percent potassium acetate in the catalyst having a weight ratio of gold to palladium in the range of 0.6 to 1.25.

WO 99/08791 describes a process for the preparation of a catalyst comprising metal nanoparticles on a porous support, in particular oxidizing ethylene and acetic acid in the gas phase to form vinyl acetate. The invention relates to a process for producing a catalyst comprising one or several metals from a group of metals comprising subgroups Ib and VIIIb of the porous support particulate element periodic table, the group of metal compounds from subgroups Ib and VIIIb of the periodic table. In the pores of the support by a first step of applying one or several precursors from the porous support and a second step in which the porous support, preferably the nanoporous support to which one or more precursors have been applied, is treated with at least one reducing agent. The resulting metal nanoparticles are characterized in that they are obtained in situ.

Typically, step (3) of the process of the invention is carried out in a heterogeneous system of reactants present in the gas phase.

The molecular oxygen containing gas used in step (3) of the process of the invention may comprise the unreacted molecular oxygen containing gas of step (1) or (2) and / or further molecular oxygen containing gas. Preferably, at least some molecular oxygen containing gas is fed independently from the acetic acid and ethylene reactants to the third reaction zone.

Step (3) of the process of the invention may suitably be carried out at a temperature in the range from 140 to 220 ° C.

Step (3) of the process of the invention may suitably be carried out at a pressure in the range from 1 to 100 bar.

Step (3) can be carried out in any suitable reactor design capable of removing the heat of reaction in a suitable manner; Preferred technical solutions are fixed bed or fluidized bed reactors.

Acetic acid conversion in the range of 5 to 50% can be achieved in step (3) of the process of the invention.

Oxygen conversion in the range of 2 to 100% can be achieved in step (3) of the process of the invention.

In step (3) of the process of the invention, suitable catalysts have a productivity (STY) in the range of 100 to 2000 g of vinyl acetate per hour per unit catalyst, but more than 10000 g of vinyl acetate per hour per unit catalyst of catalyst may also be suitable.

The third product stream from step (3) of the process comprises vinyl acetate and water, and also any unreacted acetic acid, ethylene, ethane, nitrogen, carbon monoxide, carbon dioxide, and traces of other byproducts may be present. In the intermediate between step (3) and step (4) of the process of the invention, in any case, suitable ethylene and ethane, carbon monoxide and carbon dioxide are removed from the third product stream from the scrubbing tower as a top gas fraction, and vinyl acetate The liquid fraction comprising water, acetic acid is preferably removed from the bottom.

The third product stream from step (3) comprising vinyl acetate, water and acetic acid and with or without the intermediate scrubbing step comprises acetic acid and top azeotrope fraction comprising acetic acid and water in step (4). The lower fraction is separated by distillation.

Vinyl acetate is recovered in step (3), for example, from an azeotrope fraction which has been suitably separated by decantation. The vinyl acetate recovered can, if desired, be further purified by known methods. The bottom fraction comprising acetic acid separated in step (3), with or without further purification steps, is preferably recovered in step (3) of the process.

The total space time yield (STY) of vinyl acetate (referred to as ethane) produced by this process is in the range of 100 to 5000 g of vinyl acetate per hour per liter of unit catalyst, preferably in the range of 500 to 1500 g.

The overall yield is determined by, for example, independently controlling the oxygen concentration and / or reaction temperature and pressure, and / or the reactant ratio of step (1) and / or step (2) and / or step (3) of the process. Or in a number of ways, including independently adjusting the reaction conditions.

The method of the present invention can now be described by way of example with reference to FIG. 1, which shows a schematic apparatus form used in the method of the present invention.

The apparatus comprises a first reaction zone 1, a second reaction zone 2, a third reaction zone 3 and a scrubber tower 4.

In use, a gaseous feedstock 5 comprising molecular oxygen-containing gas, any vapor and essentially ethane is fed to the first reaction zone 1 comprising an active catalyst used to oxidize ethane to form acetic acid. Depending on the scale of the process, the first reaction zone 1 may comprise a single reactor or several reactors in parallel or in series. In addition, the first reaction zone may comprise a reactor multistage capable of supplying additional oxygen containing gas between independent reactors. A first gaseous product stream comprising acetic acid, unreacted feedstock, any unconsumed molecular oxygen containing gas and water is removed from the first reaction zone 1 together with carbon monoxide, carbon dioxide and an inert material.

The second reaction zone 2 is fed a gaseous feedstock 6 comprising molecular oxygen containing gas, optional vapor and essentially ethane. The reaction zone 2 contains an active catalyst used to oxidize ethane to form ethylene. Depending on the scale of the process, the second reaction zone 2 may comprise a single reactor or several reactors in parallel or in series. In addition, the second reaction zone may comprise a reactor multistage capable of supplying further molecular oxygen containing gas between independent reactors. A second gas product stream comprising ethylene, unreacted feedstock, any non-consumable molecular oxygen containing gas and water is removed from the second reaction zone 2 together with carbon monoxide, carbon dioxide and inert material.

The first and second product streams are fed to a third reaction zone. Additional molecular oxygen containing gas 7 can be mixed with the product stream removed from the first and second reaction zones 1 and 2. In the third reaction zone 3, acetic acid and ethylene are contacted with a molecular oxygen-containing gas in the presence of an active catalyst used to make vinyl acetate. Depending on the scale of the process, the third reaction zone 3 may comprise a single reactor or several reactors in parallel or in series. The product stream comprising vinyl acetate, water, any ethane, gas by-products and unreacted acetic acid and ethylene is removed from the third reaction zone and fed to the scrubber tower 4, where ethylene and any ethane are inert A gas stream comprising the material, carbon monoxide and carbon dioxide by-products is removed from the top and recovered to the first and second reaction zones (1) / (2). The liquid stream comprising vinyl acetate, water, unreacted acetic acid and other high boiling products that may be present in the process is removed from the bottom of the scrubber tower 4 and the vinyl acetate is separated into a modern plant (not shown). For example, vinyl acetate and water fed to the distillation column are removed as an azeotrope and acetic acid and other high boiling products that may be present are removed as bleed from the bottom of the column. The water in the top stream from the distillation column can be separated from vinyl acetate in a decanter, and the vinyl acetate product stream removed from the decanter is purified by conventional methods known in the art.

Carbon dioxide by-products can be removed by any viable technical method known in the art, namely by reversible adsorption in aqueous K ₂ CO ₃ solution recovered in an adsorption tower (not shown).

The invention is illustrated in the following examples.

Preparation of the catalyst

Example (1)

Preparation of Catalyst I: Mo _1.00 Pd _0.00075 V _0.55 Nb _0.09 Sb _0.01 Ca _0.01 O _x

Solution 1

80 g of ammonium molybdate (Riedel-de Haen) in 400 ml of water.

Solution 2

29.4 g of ammonium metavanadate in 400 ml of water from Riedel-de Jaen.

Solution 3

Niobium ammonium oxalate in 200 ml of water from H. Seed. Starck] 19.01 g, Amthymonix oxalate [manufactured by Pfaltz & Bauer] and calcium nitrate [manufactured by Riedel-de Jaen] 1.34 g.

Solution 4

0.078 g of palladium (II) acetate (Aldrich) in 200 mL of ethanol.

Solutions 1, 2 and 3 were individually stirred at 70 ° C. for 15 minutes. Then solution 3 was poured into solution 2, stirred for an additional 15 minutes at 70 ° C. and added to solution 1. Thereafter, solution 4 was added.

The resulting mixture was evaporated to yield 800 ml of total volume remaining. The mixture is spray dried at 180 ° C., then the powder is dried in static air at 120 ° C. for 2 hours and calcined at 300 ° C. for 5 hours.

Example (2)

Preparation of Catalyst II: K, Pd, Au / TiO ₂

2.11 g of palladium acetate (Aldrich) and 1.32 g of gold acetate were dissolved in 30 ml of acetic acid. The preparation of the gold acetate used is described, for example, in US Pat. No. 4,933,204. 100 ml of TiO ₂ support (P25 pellets, Degussa, Hanau) was added to the palladium and gold acetate solution. Subsequently, most of the acetic acid was evaporated at 70 ° C. using a rotary evaporater, then the remainder was evaporated at 60 ° C. using an oil pump, and finally a vacuum drying cabinet (at 14 ° C. for 14 hours). evaporated in a vacuum drying cabinet.

While the gas (40 L / h) was passed through the pellets directly at 500 ° C. and 1 bar for 1 hour, the obtained pellets were reduced using 10% by volume of a gas mixture of hydrogen in nitrogen. While the potassium ions were loaded, the reduced pellets were added in a stirring device for 15 minutes with a solution containing 4 g of potassium acetate in 30 ml of water.

The solvent was then evaporated using a rotary evaporator. The pellet was dried at 100 ° C. for 14 hours.

Catalyst II is prepared in three batches using the same method and these are referred to as IIa, IIb and IIc, respectively.

All catalysts were then compressed, crushed and sieved to a particle fraction of 0.35 to 0.70 mm to effect catalyst testing.

Catalyst test

In order to carry out the catalytic reaction described in steps (1), (2) and (3) of the present invention, a double wall fixed bed reactor having an internal diameter of 14 mm and 20 mm and a length of 350 mm respectively was used. The reactor is heated through an outer tube with an oil bath. Typically, 5 ml and 15 ml of catalyst, respectively, are used to determine the volume ratio of catalyst to inert material together with several inert materials, typically glass, quartz or alumina particles or beads in the catalyst, for example. For example, 2: 1, 1: 1, 1: 2 or 1: 5 was mixed partially. In order to reduce the unused volume of the reactor, an inert material (as described above) was charged before and after the catalyst bed. Typically, volumetric flow was controlled by mass or liquid flow controllers, respectively.

Analysis of the reaction product was carried out by on-line gas chromatography.

In order to carry out steps (1) and (2) of the present invention using one single reactor, the catalyst measurement results on catalysts I to XIII (Examples (1 to 13)) are shown in Tables 1 and 2. The measurement of step 1 (results are shown in Table 1) is carried out at 15 bar.

The data in Tables 1 and 2 were defined as follows:

% Conversion of ethane =

(0.5 * [CO] + 0.5 * [CO ₂ ] + [C ₂ H ₄ ] + [CH ₃ COOH]) / (0.5 * [CO] + 0.5 * [CO ₂ ] + [C ₂ H ₄ ] + [ C ₂ H ₆ ] + [CH ₃ COOH]) * 100

Selectivity for ethylene [%] =                 

([C ₂ H ₄ ]) / (0.5 * [CO] + 0.5 * [CO ₂ ] + [C ₂ H ₄ ] + [CH ₃ COOH]) * 100

Selectivity for acetic acid [%] =

([CH ₃ COOH]) / (0.5 * [CO] + 0.5 * [CO ₂ ] + [C ₂ H ₄ ] + [CH ₃ COOH]) * 100

[] = mol% concentration

[C ₂ H ₆ ] = concentration of unconverted ethane

τ [s] = catalyst volume (ml) / gas volume flow (ml / s) at reaction conditions

STY = g product / (l catalyst * h)                 

Reaction conditions result Feed composition Conversion rate Selectivity Space time yield Conduct number                                          T [° C] τ [s] V (C ₂ H ₆ ) [ml / s] V (O ₂ ) [ml / s] V (N ₂ ) [ml / s] V (H ₂ O) [ml / h] X (C ₂ H ₆ ) [%] S (HOAc) [%] S (C ₂ H ₄ ) [%] S (CO + CO ₂ ) [%] STY (HOAc) [g / (hℓ)]                                          One                                          280 14.8 1.0 0.2 0.8 1.4 13.3 91.5 0.7 7.8 235 2                                          280 7.4 2.0 0.4 1.6 2.9 10.5 90.4 3.5 6.0 362 3                                          300 7.1 2.0 0.4 1.6 2.9 13.2 89.0 2.0 9.0 447 4                                          300 4.8 3.0 0.6 2.4 4.3 11.3 87.2 5.5 7.3 564 5                                          300 4.1 3.5 0.7 2.8 5.0 10.2 86.2 7.4 6.4 584 6                                          300 3.7 4.0 0.8 3.2 5.0 9.9 84.1 9.2 6.6 630

Catalyst II (Example (2)) is used in step (3) of the present invention for the production of vinyl acetate. The catalyst test is carried out at a reaction temperature in the range of 150 to 170 ° C. and a reaction pressure of 8 to 9 bar.

Table 2 shows the catalyst measurement results of Catalyst II (Example (2)) for carrying out step (3) of the present invention.

The data in Table 2 is defined as follows:

Selectivity for vinyl acetate (VAM) [%] =

([VAM]) / ([VAM] + 0.5 * [CO] + 0.5 * [CO ₂ ]) * 100

[] = mol% concentration                 

STY = g product / (l catalyst * h)

Catalyst Results of Catalyst II Conducting Vinyl Acetate Synthesis Reaction conditions result Selectivity Space time yield number T [℃] P [bar] S (VAM) [%] STY [g / (hℓ)] a 155 9 98 1000 a 160 9 98 1050 a 170 9 96 1000 b 160 9 98 1150 b 170 9 97 700 c 170 9 98 1300

Claims (23)

delete delete delete delete delete delete delete delete In a first reaction zone of 1 to 100 atmospheres, a gaseous feedstock comprising essentially ethane is contacted in the presence of a catalyst with steam of greater than 0 to 50 vol% based on the total volume of the molecular oxygen-containing gas and gaseous feedstock Producing (1) a first product stream comprising acetic acid, Contacting a gaseous feedstock comprising essentially ethane in a second reaction zone of from 1 to 50 atmospheres with a molecular oxygen containing gas in the presence of a catalyst to produce a second product stream comprising ethylene (2), (3) contacting the first gaseous product stream and the second gaseous product stream with a molecular oxygen containing gas in the presence of a catalyst in a third reaction zone to produce a third product stream comprising vinyl acetate, and Separating the product stream from step (3) and recovering vinyl acetate from the product stream from step (3), wherein the catalyst in the first reaction zone and the second reaction zone is Characterized in that the compound of, vinyl acetate integrated process. Formula IV Mo _a Pd _b X _c Y _d In the above formula, X is selected from one or more elements from the group consisting of Cr, Mn, Nb, Ta, Ti, V, Te and W, Y is B, Al, Ga, In, Pt, Zn, Cd, Bi, Ce, Co, Rh, Ir, Cu, Ag, Au, Fe, Ru, Os, K, Rb, Cs, Mg, Ca, Sr, Is selected from one or more elements from the group consisting of Ba, Nb, Zr, Hf, Ni, P, Pb, Sb, Si, Sn, Tl and U, a, b, c and d are the gram (g) atomic ratio, respectively a is 1, b is 0.0001 to 0.01, c is 0.4 to 1, d is 0.005-1. 10. The process of claim 9, wherein the gaseous feedstock of step (1) comprises ethane and molecular oxygen containing gas in the range of 1: 1 to 10: 1 as the ratio of ethane to oxygen. The process according to claim 9 or 10, wherein the gaseous feedstock of step (2) comprises ethane and molecular oxygen containing gas in the range of 1: 1 to 10: 1 as the ratio of ethane to oxygen. delete 10. The process of claim 9, wherein b, c and d, in gram (g) atomic ratios, in the catalyst of Formula IV are each b from 0.0001 to 0.005, c from 0.5 to 0.8, and d from 0.01 to 0.3. delete delete delete delete delete delete The process according to claim 9 or 10, wherein additional acetic acid from vinyl acetate separation is fed to the third reaction zone. The process according to claim 9 or 10, wherein the molecular oxygen containing gas is fed independently from the ethane feedstock into the first reaction zone, the second reaction zone or both zones. The method of claim 11, wherein the molecular oxygen containing gas is fed independently from the ethane feedstock into the first reaction zone, the second reaction zone, or both zones. The process according to claim 9 or 10, wherein the molecular oxygen containing gas is fed independently from the acetic acid and ethylene reactants into the third reaction zone.

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