JP5249717B2 - Method for oxidizing carbon monoxide and / or unsaturated hydrocarbon - Google Patents

Description

  The present invention relates to a method for producing chlorine by oxidizing at least one selected from carbon monoxide and unsaturated hydrocarbon, hydrogen chloride, and oxygen to oxidize hydrogen chloride in the presence of a catalyst. The present invention relates to a method for oxidizing carbon oxide and / or unsaturated hydrocarbon.

  A method of producing chlorine by oxidizing at least one selected from carbon monoxide and unsaturated hydrocarbon, hydrogen chloride, and oxygen to oxidize hydrogen chloride in the presence of a catalyst; and carbon monoxide and / or Alternatively, there is a method of oxidizing unsaturated hydrocarbons. As a catalyst used in these oxidation methods, Patent Document 1 describes a catalyst obtained by supporting a ruthenium compound on a titanium oxide support calcined at a calcining temperature of 700 ° C.

However, the conventional catalyst as described in Patent Document 1 is easily deteriorated when it comes into contact with carbon monoxide and / or an unsaturated hydrocarbon under the reaction conditions when hydrogen chloride is oxidized with oxygen. May decrease.
JP 2002-226205 A

  The problem of the present invention is that, even in a reaction system in which carbon monoxide and / or unsaturated hydrocarbons coexist with hydrogen chloride, chlorine can be produced by stably oxidizing hydrogen chloride over a long period of time. It is to provide a method capable of oxidizing carbon and / or unsaturated hydrocarbons.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a catalyst obtained by supporting a ruthenium compound on a titanium oxide support calcined at a relatively low calcining temperature of 200 to 500 ° C. A new finding that when used in the reaction, it is possible to suppress a reduction in the oxidation activity of the catalyst even in a reaction system in which at least one selected from carbon monoxide and unsaturated hydrocarbon coexists with hydrogen chloride. As a result, the present invention has been completed.

That is, the chlorine production method of the present invention has the following configuration.
(1) Supplying at least one selected from carbon monoxide and unsaturated hydrocarbons, hydrogen chloride, and oxygen to oxidize hydrogen chloride in the presence of a catalyst in which a ruthenium compound is supported on a titanium oxide carrier And the catalyst is obtained by supporting a ruthenium compound on a titanium oxide support calcined at a calcining temperature of 200 to 500 ° C. .
(2) The method for producing chlorine according to (1), wherein the ruthenium compound contains ruthenium oxide.
(3) The method for producing chlorine according to the above (1) or (2), wherein the supply amount of carbon monoxide and / or unsaturated hydrocarbon is 5 mol% or less with respect to hydrogen chloride.

The oxidation method of carbon monoxide and / or unsaturated hydrocarbon of the present invention has the following constitution.
(4) Supplying at least one selected from carbon monoxide and unsaturated hydrocarbon, hydrogen chloride, and oxygen, and in the presence of a catalyst in which a ruthenium compound is supported on a titanium oxide carrier, A method for oxidizing unsaturated hydrocarbons, characterized in that the catalyst is obtained by supporting a ruthenium compound on a titanium oxide support calcined at a calcining temperature of 200 to 500 ° C. A method for oxidizing carbon oxide and / or unsaturated hydrocarbon.
(5) The oxidation method according to (4), wherein the ruthenium compound contains ruthenium oxide.
(6) The oxidation method according to (4) or (5), wherein the supply amount of carbon monoxide and / or unsaturated hydrocarbon is 5 mol% or less with respect to hydrogen chloride.

  According to the present invention, even in a reaction system in which carbon monoxide and / or unsaturated hydrocarbon coexists with hydrogen chloride, chlorine can be produced by stably oxidizing hydrogen chloride over a long period of time. The effect is that carbon and / or unsaturated hydrocarbons can be oxidized.

  The production of chlorine and the oxidation of carbon monoxide and / or unsaturated hydrocarbon according to the present invention are carried out in the presence of a catalyst. The catalyst is formed by supporting a ruthenium compound on a titanium oxide support. The catalyst is preferably prepared through each step in the order of a molding step, a firing step, and a supporting step.

<Molding process>
When the catalyst is used in a fixed bed reactor, it is usually shaped. The forming step in the present invention means a step of forming a carrier containing titanium oxide, that is, a titanium oxide carrier.

  Examples of the method for forming the titanium oxide carrier include an extrusion molding method, a tableting molding method, and a spray molding method. Examples of the shape of the obtained molded body include a spherical shape, a cylindrical shape, a ring shape, and an amorphous granular shape. In addition, after molding, pulverization and classification to an appropriate size may be performed. At that time, it is preferable to perform pulverization and classification so that the diameter of the obtained catalyst is 10 mm or less. The catalyst diameter means the diameter of a sphere in the case of a sphere, the diameter of a circle of a cross section in the case of a cylinder, and the longest diameter of an arbitrary cross section in the case of other shapes.

  The titanium oxide carrier needs to contain titanium oxide, but if necessary, for example, oxides such as alumina, silica, zirconium oxide, niobium oxide, composite oxides composed of one or more types of activated carbon and titanium oxide, These exemplified mixtures may be contained. In particular, a carrier made of titanium oxide having a rutile crystal structure is preferably used. As the titanium oxide, those having a small content of sodium and a small content of calcium are preferably used.

<Baking process>
The molded body obtained in the molding step is fired in the firing step to prepare a titanium oxide carrier. If the titanium oxide support is prepared in the order of the forming step and the firing step, the strength of the support can be improved.

  Here, the firing temperature for firing the molded body is 200 to 500 ° C, preferably 350 to 450 ° C. In the present invention, the compact is fired at a firing temperature lower than the normal firing temperature (about 700 ° C.) (200 to 500 ° C.) to obtain a titanium oxide carrier. Thus, a catalyst obtained by supporting a ruthenium compound on a titanium oxide support calcined at a relatively low calcining temperature is a reaction system in which at least one selected from carbon monoxide and unsaturated hydrocarbon coexists with hydrogen chloride. In this case, it is possible to suppress a decrease in oxidation activity. The reason for this is presumed as follows.

  That is, a plurality of hydroxyl groups usually exist on the surface of the titanium oxide carrier. The interaction between the hydroxyl group and the ruthenium compound is considered to improve the resistance to carbon monoxide and unsaturated hydrocarbons. The surface of the titanium oxide carrier baked at a relatively low calcination temperature of 200 to 500 ° C. in the present invention has more hydroxyl groups than the surface of the titanium oxide carrier baked at a normal calcination temperature. That is, the surface of the titanium oxide support baked at a calcination temperature of 200 to 500 ° C. has a sufficient hydroxyl group, and the reduction of the oxidation activity is suppressed by the interaction between the hydroxyl group and the ruthenium compound. It is guessed.

  On the other hand, if the calcination temperature is too high, the activity of the catalyst decreases. On the other hand, if the firing temperature is too low, the strength of the carrier decreases.

  The firing step is performed in a gas atmosphere such as an inert gas, an oxidizing gas, or a reducing gas. Examples of the inert gas include nitrogen and helium. Examples of the oxidizing gas include air, oxygen, and a mixed gas of nitrogen and oxygen. Examples of the reducing gas include hydrogen, Examples thereof include a mixed gas of hydrogen and nitrogen, and these may be used alone or in combination. The firing time is usually about 1 to 5 hours, and the heating rate up to the firing temperature is about 100 to 300 ° C./hour.

<Supporting process>
A ruthenium compound is supported on the titanium oxide support obtained in the calcining step to obtain the catalyst according to the present invention. Examples of the ruthenium compound include halides, oxides, oxo acids and salts thereof, halogeno acids and salts thereof, oxyhalides, oxyhalogeno acids and salts thereof, etc. They may be used, or two or more of them may be used.

In particular, ruthenium chloride as a chloride and ruthenium oxide as an oxide are preferably used. Usually, ruthenium trichloride (RuCl ₃ ) having an oxidation number of ruthenium of +3 is used as ruthenium chloride, and ruthenium dioxide (RuO ₂ ) having an oxidation number of ruthenium of +4 is used as ruthenium oxide.

  The ruthenium compound may be substantially composed of only a ruthenium compound, or a complex composed of a ruthenium compound and another compound, for example, a complex oxide composed of ruthenium oxide and another oxide. There may be. In particular, a ruthenium compound containing ruthenium oxide is preferably used.

  The loading ratio of the ruthenium compound in the catalyst is usually expressed as a mass ratio of the ruthenium compound to the total mass of the carrier and the ruthenium compound, and is usually 0.1 to 20% by mass, preferably 0.5 to 15% by mass, more preferably 1 ˜15 mass%.

  Examples of a method for supporting a ruthenium compound on a titanium oxide carrier include a method of impregnating a titanium oxide carrier with a ruthenium compound solution, a method of immersing a titanium oxide carrier in a ruthenium compound solution, and adsorbing the ruthenium compound onto the carrier. Is mentioned. Further, as described in, for example, JP-A-2002-79093, after a ruthenium compound such as ruthenium chloride is supported on a titanium oxide carrier, it is reduced with hydrazine or the like, if necessary, and then in an oxygen-containing gas atmosphere. It can prepare suitably by baking.

  In the present invention, in the presence of such a catalyst, at least one selected from carbon monoxide and unsaturated hydrocarbons, hydrogen chloride, and oxygen are supplied. In a reaction system in which at least one selected from carbon monoxide and unsaturated hydrocarbons coexists with hydrogen chloride, hydrogen chloride is oxidized to produce chlorine, and carbon monoxide and / or unsaturated carbonization is produced. Oxidizes hydrogen.

  Examples of the unsaturated hydrocarbon include aliphatic hydrocarbons having 2 to 6 carbon atoms such as ethylene, acetylene, propylene, butene, and butadiene, and those having 4 to 6 carbon atoms such as cyclobutene, cyclopentene, cyclopentadiene, cyclohexene, and cyclohexadiene. Although C6-C10 aromatic hydrocarbons, such as alicyclic hydrocarbon, benzene, toluene, xylene, ethylbenzene, naphthalene, etc. are mentioned, this invention is not limited to these illustrated.

  Here, in the case of producing chlorine by oxidizing hydrogen chloride with oxygen, in the raw material hydrogen chloride and oxygen, or in an inert gas that can be supplied together with these, due to its preparation method, generation source, etc. If carbon monoxide and unsaturated hydrocarbons are contained as impurities, these impurities may poison the catalyst and reduce its oxidation activity against hydrogen chloride. Conventionally, such impurities have been removed and then subjected to an oxidation reaction of hydrogen chloride, or hydrogen chloride is oxidized to chlorine while oxidizing these impurities to carbon dioxide to make them harmless.

  However, in the former case, it takes a cost to remove impurities, and even in the latter case, the sustainability of the catalyst activity is not sufficient. According to the present invention, even in a reaction system in which carbon monoxide and / or unsaturated hydrocarbons coexist with hydrogen chloride, carbon monoxide and / or unsaturated hydrocarbons are oxidized stably over a long period of time for the reasons described above. However, chlorine can be produced.

  Therefore, according to the present invention, as a raw material hydrogen chloride, for example, a gas generated by the reaction of hydrogen and chlorine, a gas generated by heating hydrochloric acid, a dehydrochlorination reaction, a pyrolysis reaction or a combustion reaction of a chlorine compound Carbon monoxide and unsaturated hydrocarbons may be included as impurities such as carbonylation reaction of organic compounds with phosgene, various by-product gases generated by chlorination reaction of organic compounds with chlorine, and combustion exhaust gas generated from incinerators Gas can be used. Further, oxygen and inert gas that can be recovered in each of these reaction systems can also be used. The supply amount of carbon monoxide and / or unsaturated hydrocarbon is suitably 5 mol% or less with respect to hydrogen chloride.

  Usually, air or pure oxygen can be used as the oxygen source. Pure oxygen can be prepared by an air pressure swing method, a cryogenic separation method, or the like. The amount of oxygen used is usually 0.1 mol times or more, preferably 0.2 mol times or more, relative to hydrogen chloride.

  The reaction temperature is usually 100 to 500 ° C, preferably 200 to 400 ° C, more preferably 250 to 350 ° C. If the reaction temperature is too low, it will be difficult to maintain the stable activity of the catalyst, while if the reaction temperature is too high, the catalyst components will be easily volatilized. The reaction pressure is usually about 0.1 to 5 MPa.

  Examples of the reaction method include a fixed bed method, a moving bed method, and the like. Usually, a gas phase reaction such as a fixed bed gas phase circulation method and a moving bed gas phase circulation method is preferably employed. The fixed bed gas phase circulation method has an advantage that it is easy to achieve a high conversion rate because the reaction product gas and the catalyst can be easily separated and the raw material gas and the catalyst can be sufficiently brought into contact with each other. On the other hand, the moving bed gas phase circulation method has an advantage that the catalyst in the reactor can be replaced without stopping the operation because the catalyst in the reactor is easily exchanged.

When the reaction is carried out in a fixed bed gas phase flow system, the supply rate of the whole gas including at least one selected from carbon monoxide and unsaturated hydrocarbons, hydrogen chloride, and oxygen supplied to the reactor is The volume supply rate of the gas with respect to the volume of the catalyst packed bed (0 ° C., converted to 1 atm), that is, expressed as GHSV (Gas Hourly Space Velocity), is usually 10 to 50000 h ⁻¹ . The gas volume supply rate (converted to 0 at 1 ° C. and 1 atm.) With respect to the cross-sectional area of the catalyst packed bed (the cross-sectional area perpendicular to the gas supply direction), that is, the so-called superficial gas linear velocity is usually 0. .1 to 20 m / sec.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited only to a following example. In the following examples, the gas supply rate (ml / min) is a converted value of 0 ° C. and 1 atm unless otherwise specified.

<Manufacture of catalyst>
First, 50 parts by mass of titanium oxide [“STR-60R” manufactured by Sakai Chemical Co., Ltd., 100% rutile type] and 100 parts by mass of α-alumina [“AES-12” manufactured by Sumitomo Chemical Co., Ltd.] 19.2 parts by mass of titania sol [“CSB” manufactured by Sakai Chemical Co., Ltd., titania content 38% by mass] and 3 parts by mass of methyl cellulose [“Metroze 65SH-4000” manufactured by Shin-Etsu Chemical Co., Ltd.] Then, pure water was added and kneaded.

  This mixture was extruded into a cylindrical shape having a diameter of 3.0 mmφ, dried, and then crushed to a length of about 4 to 6 mm. The obtained molded body was heated in air from room temperature to 400 ° C. over 2 hours and fired at the same temperature for 3 hours to obtain a white titanium oxide carrier.

Next, a catalyst carrying a ruthenium compound containing ruthenium oxide was prepared in the following manner. That is, 4.29 g of ruthenium chloride [“RuCl ₃ · nH ₂ O” manufactured by NE Chemcat Co., Ltd., Ru content 40.0 mass%] 0.922 g was added to 23.8 g of the titanium oxide support obtained above. An aqueous solution prepared by dissolving in pure water was impregnated, allowed to stand, and calcined at 250 ° C. for 2 hours under air flow to obtain a blue-gray catalyst. The calculated value of the ruthenium oxide content was the formula: RuO ₂ / (RuO ₂ + TiO ₂ ) × 100 = 2.0% by mass.

<Evaluation>
An oxidation reaction (accelerated life test under high SV (Space Velocity) conditions) was performed using the obtained catalyst. That is, 0.5 g of catalyst is packed in a quartz reaction tube having an inner diameter of 13 mm, where carbon monoxide gas is 4.5 ml / min, hydrogen chloride gas is 150 ml / min (0.40 mol / hour), oxygen gas Was supplied at a rate of 75 ml / min and nitrogen gas at a rate of 40.5 ml / min under normal pressure, the reaction tube was heated to 290 ° C., and an oxidation reaction was carried out at a reaction pressure of 0.1 MPa for 50 hours. The supply amount of carbon monoxide gas is 3 mol% with respect to hydrogen chloride gas.

  At each time point 1.5 hours, 19 hours, and 44 hours after the start of the reaction, the conversion rate of hydrogen chloride and the conversion rate of carbon monoxide were determined. The measurement methods for the respective conversion rates are shown below, and the results are shown in Table 1 together with the catalyst layer temperature. In Table 1, “carrier firing temperature” means the temperature at which the molded body is fired in the preparation of the titanium oxide carrier.

(Hydrogen chloride conversion)
Sampling was performed for 20 minutes by flowing the gas at the outlet of the reaction tube through a 30% by mass potassium iodide aqueous solution, the amount of chlorine produced was measured by the iodometric titration method, and the chlorine production rate (mol / hour) was determined. The conversion rate of hydrogen chloride was calculated by applying the chlorine generation rate and the hydrogen chloride gas supply rate to the following formula (I).

(Conversion rate of carbon monoxide)
Residual gas that was not absorbed in the potassium iodide aqueous solution for 12 to 19 minutes from the start of the sampling was collected in a gas bag, analyzed by gas chromatography, and the residual amount (mole) of carbon monoxide and dioxide dioxide. The amount of carbon produced (mol) was determined and applied to the following formula (II) to calculate the conversion of carbon monoxide.

[Comparative example]
<Manufacture of catalyst>
First, a white titanium oxide carrier was obtained in the same manner as in the above example except that the firing temperature of the compact was changed to 800 ° C. instead of 400 ° C. Next, a blue-gray catalyst on which a ruthenium compound containing ruthenium oxide was supported was obtained in the same manner as in the above Example. The calculated value of the ruthenium oxide content was the formula: RuO ₂ / (RuO ₂ + TiO ₂ ) × 100 = 2.0% by mass.

<Evaluation>
Using the obtained catalyst, an oxidation reaction was carried out in the same manner as in the above Example. Then, at each time point after 1.5 hours, 20 hours, and 44 hours from the start of the reaction, the conversion rate of hydrogen chloride and the conversion rate of carbon monoxide were determined in the same manner as in the above example. The results are shown in Table 1 together with the catalyst layer temperature.

  As is clear from Table 1, the examples using the catalyst obtained by supporting the ruthenium compound on the titanium oxide support calcined at a calcining temperature of 200 to 500 ° C. were calcined at a calcining temperature higher than 500 ° C. Compared to a comparative example using a catalyst obtained by supporting a ruthenium compound on a titanium oxide carrier, each conversion rate of hydrogen chloride and carbon monoxide can be suppressed from decreasing over time. Recognize.

Claims (2)

At least one selected from carbon monoxide and unsaturated hydrocarbon, hydrogen chloride, and oxygen are supplied, and in the presence of a catalyst in which a ruthenium compound is supported on a titanium oxide support, carbon monoxide and / or unsaturated carbon is present. A method for oxidizing saturated hydrocarbons, comprising:
The catalyst is obtained by supporting 0.1 to 20% by mass of a ruthenium compound with respect to the total mass of the carrier and the ruthenium compound on a titanium oxide support calcined at a calcining temperature of 200 to 500 ° C. for 1 to 5 hours. are those der is, and the supply amount of carbon monoxide and / or unsaturated hydrocarbons, carbon monoxide and / or unsaturated hydrocarbons to 5 mol% or less der wherein Rukoto against hydrogen chloride Oxidation method. The ruthenium compound, oxidizing method of claim 1 comprising ruthenium oxide.