Title of the invention: Catalyst for hydrolysis of carbonyl sulfide and method for producing the same
Technical field
[0001]
　The present invention relates to a carbonyl sulfide hydrolysis catalyst and a method for producing the same, and more particularly to a carbonyl sulfide hydrolysis catalyst and a method for producing the same for use in fuel gas of a gas turbine. This application claims the priority based on Japanese Patent Application No. 2018-003524 filed on January 12, 2018, and uses the entire contents of the description.
Background technology
[0002]
　Conventionally, in a gas production plant such as a coal gasification plant, a method of removing sulfur compounds contained in a coal gasification gas, which is a raw material gas, to prevent air pollution, equipment corrosion in the plant, etc. has been performed. .. For example, in an integrated coal gasification combined cycle power plant (IGCC), after converting COS in coal gasification gas into hydrogen sulfide (H 2 S) using a catalyst that hydrolyzes carbonyl sulfide (COS) , The sulfur compound is removed from the raw material gas by removing the H 2 S of. The gas from which the sulfur compounds have been removed is used as fuel for gas turbines.
[0003]
　Such a catalyst and method include a catalyst for hydrolysis of carbonyl sulfide, which is obtained by adding and supporting a metal sulfate or a metal carbonate as a co-catalyst to anatase-type titanium, and in the presence of water in a reducing gas atmosphere. Then, a method of hydrolyzing carbonyl sulfide in the presence of the catalyst is known (for example, Patent Document 1).
Prior art documents
Patent literature
[0004]
Patent Document 1: Japanese Patent Laid-Open No. 11-276897
[0005]
　Although such a catalyst has a high COS conversion rate for converting COS in gas to H 2 S immediately after use, there is a problem that the COS conversion rate decreases with use time.
Summary of the invention
[0006]
　In view of the above circumstances, an object of the present invention is to provide a COS hydrolysis catalyst that can maintain a high COS conversion rate even when used for a long time, and a method for producing the same.
[0007]
　The present invention, in one aspect, is a catalyst for COS hydrolysis. The catalyst contains titanium dioxide and a barium compound supported on the titanium dioxide, and when Ba and S in the catalyst are converted into BaO and SO 3 , respectively , the molar ratio of SO 3 to BaO in the catalyst is The ratio is 1 or more.
[0008]
　In one aspect of the present invention, it is preferable that the barium compound is supported on the titanium dioxide in an amount of 2% by mass or more and 8% by mass or less with respect to the catalyst in terms of the barium oxide.
[0009]
　In one aspect of the present invention, it is preferable that the molar ratio of SO 3 to BaO in the catalyst is 2.1 or more.
[0010]
　The present invention, in one aspect, is a method for producing a COS hydrolysis catalyst. In the production method, titanium dioxide containing sulfate is added to a barium acetate solution and kneaded to obtain a kneaded product, a step of extruding the kneaded product to obtain a shaped catalyst, and drying the shaped catalyst. And a calcination step of obtaining a titanium dioxide catalyst carrying a barium compound by calcination after the drying step, wherein Ba and S in the catalyst are converted into BaO and SO 3 , respectively. The molar ratio of SO 3 to BaO in the catalyst is 1 or more.
[0011]
　In one aspect of the present invention, it is preferable that, in the step of obtaining the kneaded product, the barium acetate solution is added in an amount of 2% by mass or more and 8% by mass or less based on the barium oxide with respect to the catalyst. is there.
[0012]
　In one aspect of the present invention, it is preferable that the molar ratio of SO 3 to BaO in the catalyst is 2.1 or more.
[0013]
　According to the present invention, a COS hydrolysis catalyst that can maintain a high COS conversion rate even when used for a long time and a method for producing the same are provided.
Brief description of the drawings
[0014]
FIG. 1 is a conceptual diagram for explaining the structure and operating principle of a system of an embodiment in which a carbonyl sulfide hydrolysis catalyst according to the present invention is adopted in an actual machine.
FIG. 2 is a graph showing the results of the COS conversion rate with respect to the treatment temperature in the examples of the catalyst for carbonyl sulfide hydrolysis and the method for producing the same according to the present invention.
MODE FOR CARRYING OUT THE INVENTION
[0015]
　Hereinafter, an embodiment of a carbonyl sulfide (COS) hydrolysis catalyst and a method for producing the same according to the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments described below. The accompanying drawings are diagrams for explaining the outline of the present embodiment, and some of the attached devices are omitted.
[0016]
1. Catalyst
　An embodiment of the COS hydrolysis catalyst according to the present invention will be described. The COS hydrolysis catalyst according to the present embodiment includes at least a carrier and a barium compound supported on the carrier.
[0017]
　The carrier is titanium dioxide (TiO 2 ). Examples of the carrier include titanium dioxide of anatase type, rutile type and brookite type. Of these, from the practical viewpoint, the carrier is preferably anatase type titanium dioxide. The specific surface area of ​​the carrier can be, for example, 30 to 300 m 2 /g. The carrier may be any carrier that can support a barium compound, and may be aluminum oxide (Al 2 O 3 ) or zirconium oxide (ZrO 2 ).
[0018]
　At least a barium compound is present in the catalyst. The amount of the barium compound may be any amount that can be supported by the carrier, and is, for example, 1% by mass or more, preferably 2% by mass or more and 8% by mass, based on the catalyst, in terms of the amount of the barium oxide compound (BaO). % Or less, and more preferably 2% by mass or more and 6% by mass or less. When the amount of the barium compound is in the range of 2% by mass or more and 8% by mass or less with respect to the catalyst, the COS conversion rate can be improved and the COS conversion rate can be improved. In the present specification, “barium oxide” is intended to mean barium oxide as a compound, and “BaO” is intended to mean BaO as a composition constituting the compound.
[0019]
　Further, S component such as sulfate is present in the catalyst. Specifically, the catalyst contains at least sulfate radicals as an unavoidable or optional mixture before its preparation. In the present specification, "sulfate group" mainly means sulfate ion (SO 4 2- ), and "S content" mainly intends to show S as a composition constituting a compound such as sulfate group. There is. It can be inferred that sulfate radicals are mixed in a small amount in the carrier raw material before the catalyst is manufactured, and a sulfate is produced in the process of manufacturing the carrier raw material, and is present in the catalyst as barium sulfate. For example, titanium dioxide, which is a carrier material, can be produced by treating ilmenite ore with sulfuric acid to produce titanium oxysulfate (TiOSO 4 ), and then calcining. It can be inferred that sulfate radicals are adsorbed on titanium dioxide during the production process of such a carrier material. Therefore, although various structures can be inferred as the structure of the compound supported on the carrier on the surface of the catalyst, at least barium sulfate can be mentioned as the barium compound supported on the carrier.
[0020]
　The molar ratio of SO 3 in the catalyst to BaO is 1.0 or more, preferably 2.1 or more, in terms of S content in the catalyst in terms of SO 3 . In addition, the amount of BaO can be converted to the amount of BaO in the amount of Ba in the catalyst. If the molar ratio of SO 3 to BaO is 1.0 or more, barium compounds such as barium sulfate (BaSO 4 ) are sufficiently present, so that even if a catalyst is used for a long time, high COS conversion can be achieved. You can maintain the rate. In the present specification, “SO 3 ”is mainly intended to indicate SO 3 as a composition constituting a compound , and “Ba content” is mainly intended to indicate Ba as a composition constituting a compound.
[0021]
　Further, the catalyst may be a shaped catalyst having a predetermined shape. Examples of the shape of the shaped catalyst include a spherical shape, a plate shape, a pellet shape, and a honeycomb shape. Among these, the shape of the shaped catalyst is preferably a honeycomb shape from a practical viewpoint. In addition, the molded catalyst may contain a binder, an organic plasticizer and the like in order to improve its moldability and strength.
[0022]
2. Production Method
　An embodiment of the method for producing the COS hydrolysis catalyst according to the present invention will be described. The COS hydrolysis catalyst according to the present embodiment includes at least a kneading step, a molding step, a drying step, and a firing step.
[0023]
　In the kneading step, a barium acetate (Ba(CH 3 COO) 2 ) aqueous solution, aqueous ammonia (NH 3 (aq)), a binder and an organic plasticizer are added to a titanium dioxide carrier material containing a sulfate group , A kneaded product is obtained by kneading using a kneader such as a kneader or a mixer. The shape of the carrier raw material is not particularly limited, but a powder shape is preferable. The concentration of ammonia water can be set to, for example, 5 to 15% by volume. The amount of ammonia water added may be, for example, an amount such that the pH value of the solution before kneading is 6 to 8. Examples of the binder include fibrous inorganic substances such as glass fiber, glass wool, rock wool, and kaool, clay minerals such as kaolin, halloysite, montmorillonite, sericite, montmorillonite, acid clay and bentonite, and combinations thereof. Examples of organic plasticizers include cellulose acetate and methylsesulose. The amount of binder may be, for example, 8 to 20 mass% with respect to the carrier raw material. The amount of the organic plasticizer can be, for example, 5 to 10 mass% with respect to the carrier raw material.
[0024]
　In the catalyst that has undergone the kneading step, the molding step, the drying step and/or the calcination step, barium acetate reacts with the sulfate group contained in the carrier raw material to produce barium sulfate, as shown in the formula (I) described below. To do.
[0025]
　The addition amount of the barium acetate solution may be any amount as long as the carrier can support the barium compound. For example, it is 1% by mass or more, and preferably 2% by mass or more 8% with respect to the catalyst in terms of the amount of barium oxide. It is at most mass%, more preferably at least 2 mass% and at most 6 mass%. When the addition amount of the barium acetate solution is in the range of 2% by mass or more and 8% by mass or less with respect to the catalyst, the rate of COS conversion can be improved and the COS conversion rate can be improved.
[0026]
　In the molding step, the kneaded product is extruded into a predetermined shape such as a honeycomb shape by using an extruder such as a vacuum extruder with a screw equipped with an extrusion nozzle to obtain a formed catalyst.
[0027]
　In the drying step, the shaped catalyst is dried at a predetermined temperature and time. The temperature and time of the drying step may be any temperature and time at which the catalyst after the molding step can be dried. For example, the temperature and time may be 60 minutes or more and 300 minutes at 80° C. or more and 110° C. using a dryer. May be dried.
[0028]
　In the calcining step, the barium compound is supported on titanium dioxide by calcining the catalyst after the drying step at a predetermined temperature for a predetermined time. The temperature of the firing step is, for example, 400° C. or higher and 600° C. or lower. The firing process time is, for example, 4 hours or more and 8 hours or less.
[0029]
[Chemical 1]

[0030]
3. System
　FIG. 1 shows a system in which the carbonyl sulfide hydrolysis catalyst according to the present embodiment can be preferably adopted. According to the system shown in FIG. 1, the catalyst according to the present embodiment can be used to purify a fuel gas suitable for power generation in a gas turbine from a raw material gas obtained by gasifying coal.
[0031]
　As shown in FIG. 1, in a gasifier 10 such as a gasifier , coal is gasified under the condition that at least oxygen (O 2 ) is present to generate a coal gasification gas as a raw material gas. R. The raw material gas is sent to the COS conversion device 20 including the catalyst according to the present embodiment inside. In the COS converter 20, in the presence of the catalyst, COS and water (H 2 O) in the gas are converted into carbon dioxide (CO 2 ) and hydrogen sulfide (H 2 S) as represented by the following formula (II). Convert. As a result, COS is decomposed and removed from the source gas. In the COS conversion device 20, the temperature measured by the thermometer 20a is adjusted to, for example, 250°C to 300°C, preferably 300°C.
[0032]
[Chemical 2]

[0033]
　Further, impurities such as halogen are mixed in the gas from which COS has been removed. Impurities in the gas are removed by washing with water or the like in the washing device 30 such as a water washing tower. Gas passing through the cleaning device 30, H 2 at S removal device 40, methyldiethanolamine (C 5 H 13 NO 2 by contacting the amine absorbent in an aqueous solution of an alkanolamine such as), H in the gas 2 and S It is absorbed and removed in the absorption liquid. In the H 2 S removing device 40, CO 2 is also removed by the amine absorbing liquid absorbing carbon dioxide in the gas . The gas that has passed through the H 2 S removal device 40 is sent to the gas turbine 50 as a purified gas. The purified gas is mixed with the compressed air compressed by a compressor (not shown) in the gas turbine 50 and burned. As a result, high-temperature and high-pressure combustion gas is generated. The gas turbine drives the turbine with combustion gas and also drives a power generation means (not shown) to generate power.
Example
[0034]
　Hereinafter, the present invention will be described in more detail with reference to Examples. The catalyst for carbonyl sulfide hydrolysis and the method for producing the same according to the present invention are not limited to the following examples.
[0035]
1.1. Preparation of Catalyst In
　Test Example 1, 1000 g of titanium dioxide powder containing sulfate was added to a barium acetate solution (4% by mass of barium oxide based on the catalyst), 10% by volume of ammonia water, and 3% by mass of glass fiber. Then, 5% by mass of kaolin and 5% by mass of cellulose acetate were added and kneaded with a kneader. The obtained kneaded product was extrusion-molded using a screw-equipped vacuum extruder equipped with a honeycomb-shaped extrusion nozzle. The obtained honeycomb-shaped molded catalyst was dried under the condition of 80° C. and calcined at 500° C. for 5 hours to obtain a catalyst.
[0036]
　In Test Example 2, 3% by mass of glass fiber and 5% by mass of kaolin, 5% by mass of cellulose acetate, and 10% by volume of aqueous ammonia were added to the same carrier material as in Test Example 1 with respect to the carrier material. In addition, it kneaded with a kneader. The resulting kneaded product was extruded into a honeycomb shape. The obtained molded catalyst was impregnated with water by immersing it in a barium acetate solution (4% by mass with respect to the catalyst in terms of barium oxide). The formed catalyst after impregnation was dried under the condition of 80° C. and calcined at 500° C. for 5 hours to obtain a catalyst.
[0037]
1.2. X-Ray Fluorescence Analysis I
　The catalysts of Test Example 1 and Test Example 2 were subjected to semi-quantitative analysis by X-ray fluorescence analysis (XRF). The semi-quantitative value was calculated from the obtained fluorescent X-ray spectrum using the FP (fundamental parameter) method. The results are shown in Table 1.
[0038]
[table 1]

[0039]
　As shown in Table 1, the molar ratio of the SO 3 composition to the BaO composition of Test Example 1 was 2.1, and the molar ratio of SO 3 to BaO of Test Example 2 was 0.48. From the results, in Test Example 1, since the molar ratio of SO 3 to BaO exceeds 1.0, barium compounds such as barium sulfate are sufficiently generated, and in Test Example 2, barium compounds such as barium sulfate are produced. It can be assumed that the production of the compound is insufficient.
[0040]
1.3. Measurement of COS Conversion Rate With
　respect to the catalysts of Test Example 1 and Test Example 2, COS hydrolysis reaction was performed by circulating a gas under predetermined conditions. The pressure was an absolute pressure calculated from the value measured by a pressure gauge. The test conditions are shown in Table 2 below. In addition, the COS concentration at the catalyst outlet at each treatment temperature was measured by gas chromatography equipped with an FPD detector. As shown in the following formula, the COS conversion rate was calculated from the COS concentration (COS concentration at the catalyst inlet) and the COS concentration at the catalyst inlet in Table 2 below. The results are shown in Figure 1.
[0041]
[Number 1]

[0042]
[Table 2]

[0043]
　As shown in FIG. 2, the catalyst of Test Example 1 had a COS conversion rate of about 67% immediately after the start of the test gas distribution, a COS conversion rate of about 68% after 16 hours of distribution, and a COS conversion rate of about 40% after distribution of 40 hours. The COS conversion rate was about 69%. On the other hand, in the catalyst of Test Example 2, the COS conversion rate immediately after the start of the test gas flow was about 78%, the COS conversion rate after 6 hours of flow was about 57%, and the COS conversion rate after 14 hours of flow was 43%. %, and the COS conversion rate after flowing for 22 hours was about 37%.
[0044]
　From the results, in the catalyst of Test Example 1, when compared with the COS conversion rate immediately after the start of the test gas distribution, the COS conversion rate after 16 hours of distribution increased by about 1%, and the COS conversion rate after 40 hours of distribution increased by about 3%. Turned out to rise. On the other hand, in the catalyst of Test Example 2, when compared with the COS conversion rate immediately after the start of the test gas distribution, the COS conversion rate after 6-hour distribution decreased by about 27% and the COS conversion rate after 14-hour distribution decreased by about 45%. However, it was found that the COS conversion rate after flowing for 22 hours decreased by about 53%.　
[0045]
1.4. Fluorescent X-ray analysis II With
　respect to the catalyst of Test Example 2, the above-mentioned gas was allowed to flow for another 2 hours. The catalyst in which a gas at 300° C. was passed for 24 hours was used as the catalyst of Test Example 3. The catalyst of Test Example 3 was subjected to semi-quantitative analysis by the fluorescent X-ray analysis method as described above. The results are shown in Table 3.
[0046]
[Table 3]

[0047]
　As shown in Table 3, in the catalyst of Test Example 3, the molar ratio of SO 3 to BaO was 1.3. From the results, it was found that the molar ratio of SO 3 to BaO increased from 0.48 to 1.3 in Test Example 3 after the gas of 300° C. was passed through the catalyst of Test Example 2 for 24 hours . Such an increase is considered to be due to H 2 S in the treatment gas being adsorbed on the catalyst during the test gas flow, or a compound containing an S content being generated by the reaction with COS or H 2 S in the treatment gas. To be However, it can be inferred that the COS conversion rate decreased due to the change in the state of the catalyst.
Industrial availability
[0048]
　According to the COS hydrolysis catalyst and the method for producing the same according to the present invention, it is possible to obtain a COS hydrolysis catalyst that can maintain a high COS conversion rate even when used for a long time.
Explanation of symbols
[0049]
　10 gasification device
　20 COS conversion device
　20a thermometer
　30 cleaning device
　40 H 2 S removal device
　50 gas turbine
The scope of the claims
[Claim 1]
　When titanium dioxide and
　a barium compound supported on the titanium dioxide
are contained and
　Ba and S in the catalyst are converted into BaO and SO 3 , respectively , the molar ratio of SO 3 to BaO in the catalyst is 1 or more. Is a catalyst for COS hydrolysis.
[Claim 2]
　The catalyst for COS hydrolysis according to claim 1, wherein the barium compound is supported on the titanium dioxide in an amount of 2% by mass or more and 8% by mass or less with respect to the catalyst, in terms of the barium oxide.
[Claim 3]
The COS hydrolysis catalyst according to claim 1 or 2, 　wherein the molar ratio of SO 3 to BaO in the catalyst is 2.1 or more.
[Claim 4]
　To titanium dioxide containing a sulfate group, a step of adding a barium acetate solution and kneading to obtain a kneaded product, a step
　of extruding the kneaded product to obtain a
　shaped catalyst, and a drying step of drying the shaped catalyst,
　And a calcination step of obtaining a titanium dioxide catalyst carrying a barium compound after the step of drying
,
　wherein Ba and S in the catalyst are converted into BaO and SO 3 , respectively . A method for producing a COS hydrolysis catalyst, wherein the molar ratio of SO 3 to BaO is 1 or more.
[Claim 5]
　In the step of obtaining the kneaded product, the production of the catalyst for COS hydrolysis according to claim 4, wherein the barium acetate solution is added in an amount of 2% by mass or more and 8% by mass or less based on the barium oxide with respect to the catalyst. Method.
[Claim 6]
　The method for producing a COS hydrolysis catalyst according to claim 4 or 5, wherein the molar ratio of SO 3 to BaO in the catalyst is 2.1 or more.