Acetylene selective hydrogenation catalyst and preparation method thereof

Abstract

The invention relates to the technical field of catalysts, in particular to a preparation method of an acetylene selective hydrogenation catalyst, which comprises the following steps: firstly, adding deionized water into a container, respectively weighing cerous nitrate and urea, dissolving the cerous nitrate and the urea in a beaker, and stirring until the cerous nitrate and the urea are dissolved; then, adding the mixed solution into a stainless steel high-pressure kettle, and putting the stainless steel high-pressure kettle into a drying oven at high temperature for 10-24 hours; and cooling to room temperature, and carrying out suction filtration, washing, drying and calcining to obtain the cerium oxide carrier material. The method comprises the following steps: dissolving a known amount of titanium butoxide into ethanol; secondly, adding the uncalcined cerium oxide carrier material into the titanium butoxide solution; stirring in a water bath until ethanol is completely evaporated; and washing, drying and calcining the Ce / Ti oxide carrier material. And finally, adding a certain amount of palladium salt solution into deionized water, dispersing the cerium / titanium bimetallic oxide carrier into the mixed solution, and adjusting the pH value. Stirring at room temperature, performing suction filtration, washing, drying and performing high-temperature reduction to obtain the acetylene selective hydrogenation catalyst.

Description

Technical Field

[0001] The invention relates to the technical field of acetylene selective hydrogenation, and in particular to an acetylene selective hydrogenation catalyst and a preparation method thereof. Background Art

[0002] At present, the main way to obtain ethylene in industry is through steam cracking of petroleum hydrocarbons. However, the olefin components produced by steam cracking of petroleum hydrocarbons usually contain trace amounts of acetylene and diolefin impurities. For example, in the polyethylene production process, the concentration of acetylene in the ethylene feed gas is required to be no more than 5ppm. If it is not removed in time, it will reduce the quality of the subsequent synthesized petrochemical products, poison the Ziegler-Natta catalyst for the subsequent polyolefin production, and even bring safety hazards to the process production line.

[0003] In the industry, the most commonly used methods in some large and medium-sized ethylene plants are solvent absorption and catalytic hydrogenation. In actual work, the two systems are also connected in series to make the operation more flexible. However, the process flow of the solution absorption method is complicated and has significant harm to the environment and human body. In contrast, the catalytic hydrogenation method is adopted by various ethylene processing plants because of its simple process, flexible operation and environmental friendliness. The catalytic hydrogenation method can reduce the production of oligomers, thus making the reaction more stable and the catalyst life longer. In the selective hydrogenation reaction of acetylene, the following three issues must be paid attention to: First, when removing acetylene impurities in ethylene, remove them as much as possible, that is, the conversion rate of acetylene; second, when acetylene is converted into ethylene, the reaction stops to avoid excessive hydrogenation, that is, the selectivity of ethylene; third, when acetylene is hydrogenated, polymerization may occur to generate polymers (green oil) that poison the catalyst, that is, the deactivation of the catalyst. Therefore, it is urgent to develop new catalysts to overcome the above problems in the acetylene conversion process.

[0004] Ethylene is one of the most important intermediate products in the petrochemical industry and a monomer of polyethylene, accounting for about 30% of the total polymer production. At present, ethylene is mainly obtained by steam cracking of petroleum hydrocarbons in industry. However, the olefin components produced in this process usually contain a small amount of acetylene impurities. If these acetylene impurities are not removed in time, they will not only reduce the quality of the subsequent synthesized petrochemical products, but may also cause poisoning of the Ziegler-Natta catalyst and even bring safety hazards to the process production line. For example, in the polyethylene production process, there are strict requirements on the concentration of acetylene in the ethylene feed gas, which must not exceed 5ppm. In order to remove acetylene impurities, the technology of selective hydrogenation of acetylene to produce ethylene is adopted in industry. In this reaction process, the conversion rate of acetylene and the selectivity of ethylene are important indicators for evaluating the reaction efficiency. Therefore, it is particularly important to develop a highly active catalyst to selectively convert acetylene into ethylene.

[0005] The purpose of the present invention is to provide an acetylene selective hydrogenation catalyst and a preparation method thereof, so as to solve the problems of low acetylene conversion rate and poor selectivity.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing an acetylene selective hydrogenation reaction catalyst, comprising the following steps:

[0008] S1: preparing cerium oxide support material for standby use;

[0009] S2: preparing a cerium / titanium bimetallic oxide support material for later use;

[0010] S3: adding a certain amount of palladium salt solution to deionized water, and dispersing the cerium / titanium bimetallic oxide support prepared in step S2) into the mixed solution to obtain a sample solution, adjusting the pH of the sample solution to 9-11, stirring uniformly at room temperature, filtering to obtain a precipitate, and then washing the catalyst with deionized water to obtain a catalyst sample, drying the obtained sample in an oven, and then reducing it with a reducing gas flow at high temperature. Thus, an acetylene selective hydrogenation catalyst is obtained.

[0011] Furthermore, the preparation method of the cerium oxide support material in step S1 is:

[0012] Deionized water is added to a container, cerium nitrate and urea are weighed and dissolved in a beaker, and stirred until dissolved to obtain a mixed solution; the mixed solution is added to a 100 mL stainless steel autoclave, and the stainless steel autoclave is placed in an oven and maintained at 100-180° C. for 10-24 hours; the stainless steel autoclave is then cooled to room temperature, the mixed solution in the stainless steel autoclave is filtered and washed to obtain a precipitate, and the precipitate is dried at 60-100° C. for 12-24 hours to obtain a solid powder; the obtained solid powder is calcined in a muffle furnace, and the heating rate is set to 5-15° C. / min to obtain a cerium oxide carrier material.

[0013] Furthermore, the molar ratio of the cerium salt to the urea is 1:1-5.

[0014] Furthermore, the calcination temperature is 300-800° C. and the calcination time is 3-8 hours.

[0015] Furthermore, the cerium salt is one or a combination of cerium nitrate, cerium acetate, cerium chloride and cerium sulfate.

[0016] Furthermore, in step S2, the preparation method of the cerium / titanium bimetallic oxide support material is:

[0017] The titanium salt is dissolved in ethanol to obtain a titanium butoxide solution, uncalcined cerium dioxide is added to the titanium butoxide solution to obtain a mixture, and the mixture is stirred in a 70°C water bath until all the ethanol is evaporated to obtain a crude cerium / titanium bimetallic oxide support material. The obtained cerium / titanium bimetallic oxide support material is washed with distilled water 3-4 times, dried in an oven at 100-180°C for 10-24h, and finally calcined in a muffle furnace, and the heating rate is set to 5-15°C / min.

[0018] Furthermore, the titanium salt includes titanium butoxide, isopropyl titanate, titanium oxysulfate, TiCl 4 、TiCl 3 One or a combination of the following.

[0019] Furthermore, the calcination temperature is 300-800° C. and the calcination time is 3-8 hours.

[0020] Furthermore, the preparation method of the acetylene selective hydrogenation catalyst in step three is:

[0021] 0.5 g / mL Pd(NO 3 ) 2 6H 2 O solution was added to 50mL of deionized water, the cerium / titanium bimetallic oxide support was dispersed in the mixed solution, 0.25M ammonia water was added dropwise, and the pH was adjusted to 9-11; after stirring at room temperature for 6 hours, the precipitate was filtered out, and the catalyst was washed with deionized water for 3-4 times. The obtained sample was dried in an oven at 100°C for 8h, and then reduced with a volume 5%-20% H2 / Ar gas flow at 350°C for 2-4h, the gas mixture flow rate was 10-30mL / min, and the heating rate was 5-15°C / min; the acetylene selective hydrogenation catalyst was obtained.

[0022] Furthermore, the palladium salt is one of palladium nitrate, palladium sulfate, palladium chloride, triphenylphosphine palladium, and palladium acetate.

[0023] Furthermore, the reduction temperature is 300-500° C.; the reduction gas is 5%-20% H2 / Ar gas flow, and the reduction time is 2-4 hours.

[0024] The present invention also provides an acetylene selective hydrogenation reaction catalyst, wherein the mass ratio of Ce / Ti in the catalyst is 0-20:1-0.

[0025] The preparation method of the acetylene selective hydrogenation catalyst provided in the above technical solution is to load palladium on a cerium / titanium bimetallic oxide support material by an impregnation method, which has the advantages of simple preparation steps, easy availability of raw materials, safe operation, etc. At the same time, the acetylene selective hydrogenation catalyst obtained by the present invention has excellent acetylene conversion rate and selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 XRD patterns of CeTi composite support (a) and Pd / Ce-Ti catalyst (b);

[0027] Figure 2 The acetylene conversion rate of Pd / Ce-Ti catalyst in the selective hydrogenation reaction of acetylene, where (acetylene mixed gas is 1% C 2 H 2 , 10% H 2 , 20%C 2 H 4 、69%N 2 Mixed gas);

[0028] Figure 3 The ethylene selectivity of Pd / Ce-Ti catalyst in the selective hydrogenation of acetylene, where (acetylene mixed gas is 1% C 2 H 2 , 10% H 2 , 20%C 2 H 4 、69%N 2 of mixed gases). DETAILED DESCRIPTION

[0029] In order to make the purpose and advantages of the present invention more clearly understood, the present invention is specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or several specific embodiments of the present invention, and does not strictly limit the scope of protection of the specific claims of the present invention.

[0030] Example 1

[0031] The first step is to prepare the cerium oxide support material

[0032] Add deionized water to the container, weigh cerium nitrate and urea in a mass ratio of 2:1 and dissolve them in a beaker, stirring until dissolved. Then, add the mixed solution to a 100mL stainless steel autoclave and put it in an oven at 180°C for 16h. Cool to room temperature, filter and wash to obtain a precipitate, and dry it at 90°C for 12h. The obtained powder is calcined at 400°C in a muffle furnace, and the heating rate is set to 5°C / min to obtain CeO2.

[0033] Step 2: Preparation of cerium / titanium bimetallic oxide support material

[0034] Dissolve a known amount of titanium butoxide in 70 mL of ethanol. Add an equal amount of uncalcined cerium dioxide to the titanium butoxide solution. Stir the mixture in a 70°C water bath until all the ethanol is evaporated. Wash the product with distilled water 3-4 times, dry it in an oven at 90°C for 12 hours, and finally calcine it in a muffle furnace at 400°C for 4 hours, with the heating rate set to 5°C / min. Obtain Ce1Ti1 catalyst.

[0035] The third step is to prepare the acetylene selective hydrogenation catalyst.

[0036] 1-10mL of 0.5g / mL Pd(NO3)2·6H2O solution was added to 50mL of deionized water, 0.5g of the composite oxide support was dispersed in the mixed solution, and 0.25M ammonia water was added dropwise to adjust the pH to 9. After stirring at room temperature for 6 hours, the precipitate was filtered and the catalyst was washed with deionized water 3-4 times. The obtained sample was dried in an oven at 100°C for 8h, and then reduced with a volume 5% H2 / Ar gas flow at 350°C for 2h, with a gas mixture flow rate of 20mL / min and a heating rate of 5°C / min. Pd-Ce1Ti1 catalyst was obtained.

[0037] The prepared composite catalyst samples were named Pd-Ce, Pd-Ce20Ti1, Pd-Ce10Ti1, Pd-Ce2Ti1, and Pd-Ti.

[0038] Comparative Example 1

[0039] The first step is to prepare the cerium oxide support material

[0040] The same carrier material as in Example 1.

[0041] Step 2: Preparation of cerium / titanium bimetallic oxide support material

[0042] Dissolve 2.5-15g of titanium butoxide in 70mL of ethanol. Add twice the mass of uncalcined cerium dioxide to the above solution. Stir the mixture in a 70℃ water bath until all the ethanol is evaporated. Wash the product with distilled water 3-4 times, dry it in an oven at 90℃ for 12h, and finally calcine it in a muffle furnace at 400℃ for 4h, with the heating rate set to 5℃ / min. Obtain Ce2Ti1 catalyst.

[0043] The third step is to prepare the acetylene selective hydrogenation catalyst.

[0044] 1-10mL of 0.5g / mL Pd(NO3)2·6H2O solution was added to 50mL of deionized water, 0.5g of the composite oxide support was dispersed in the mixed solution, and 0.25M ammonia water was added dropwise to adjust the pH to 9. After stirring at room temperature for 6 hours, the precipitate was filtered and the catalyst was washed with deionized water 3-4 times. The obtained sample was dried in an oven at 100°C for 8h, and then reduced with a volume 5% H2 / Ar gas flow at 350°C for 2h, with a gas mixture flow rate of 20mL / min and a heating rate of 5°C / min. Pd-Ce2Ti1 catalyst was obtained.

[0045] Comparative Example 2

[0046] The first step is to prepare the cerium oxide support material

[0047] The same carrier material as in Example 1.

[0048] Step 2: Preparation of cerium / titanium bimetallic oxide support material

[0049] Dissolve a known amount of titanium butoxide in 70 mL of ethanol. Add ten times the mass of uncalcined cerium dioxide to the above solution. Stir the mixture in a 70°C water bath until all the ethanol is evaporated. Wash the product with distilled water 3-4 times, dry it in an oven at 90°C for 12 hours, and finally calcine it in a muffle furnace at 400°C for 4 hours, with the heating rate set to 5°C / min. Obtain Ce10Ti1 catalyst.

[0050] The third step is to prepare the acetylene selective hydrogenation catalyst.

[0051] A certain amount of 0.5g / mL Pd(NO3)2·6H2O solution was added to 50mL deionized water, 0.5g of the composite oxide support was dispersed in the mixed solution, and 0.25M ammonia water was added dropwise to adjust the pH to 9. After stirring at room temperature for 6 hours, the precipitate was filtered and the catalyst was washed with deionized water 3-4 times. The obtained sample was dried in an oven at 100°C for 8h, and then reduced with a volume 5% H2 / Ar gas flow at 350°C for 2h, with a gas mixture flow rate of 20mL / min and a heating rate of 5°C / min. Pd-Ce10Ti1 catalyst was obtained.

[0052] Comparative Example 3

[0053] The first step is to prepare the cerium oxide support material

[0054] The same carrier material as in Example 1.

[0055] Step 2: Preparation of cerium / titanium bimetallic oxide support material

[0056] Dissolve a known amount of titanium butoxide in 70 mL of ethanol. Add twenty times the mass of uncalcined cerium dioxide to the above solution. Stir the mixture in a 70°C water bath until all the ethanol is evaporated. Wash the product with distilled water 3-4 times, dry it in an oven at 90°C for 12 hours, and finally calcine it in a muffle furnace at 400°C for 4 hours, with the heating rate set to 5°C / min. Obtain Ce20Ti1 catalyst.

[0057] The third step is to prepare the acetylene selective hydrogenation catalyst.

[0058] A certain amount of 0.5g / mL Pd(NO3)2·6H2O solution was added to 50mL deionized water, 0.5g of the composite oxide support was dispersed in the mixed solution, and 0.25M ammonia water was added dropwise to adjust the pH to 9. After stirring at room temperature for 6 hours, the precipitate was filtered and the catalyst was washed with deionized water 3-4 times. The obtained sample was dried in an oven at 100°C for 8h, and then reduced with a volume 5% H2 / Ar gas flow at 350°C for 2h, with a gas mixture flow rate of 20mL / min and a heating rate of 5°C / min. The Pd-Ce20Ti1 catalyst was obtained.

[0059] Comparative Example 4

[0060] The first step is to prepare the cerium oxide support material

[0061] Add deionized water to the container, weigh cerium nitrate and urea in a mass ratio of 2:1 and dissolve them in a beaker, stirring until dissolved. Then, add the mixed solution to a 100mL stainless steel autoclave and put it in an oven at 180°C for 16h. Cool to room temperature, filter and wash to obtain a precipitate, and dry it at 90°C for 12h. The obtained powder is calcined at 400°C in a muffle furnace, and the heating rate is set to 5°C / min to obtain CeO2.

[0062] The second step is to prepare the acetylene selective hydrogenation catalyst.

[0063] A certain amount of 0.5g / mL Pd(NO3)2·6H2O solution was added to 50mL deionized water, 0.5g cerium oxide support was dispersed in the above solution, and 0.25M ammonia water was added dropwise to adjust the pH to 9. After stirring at room temperature for 6 hours, the precipitate was filtered and the catalyst was washed with deionized water 3-4 times. The obtained sample was dried in an oven at 100°C for 8h, and then reduced with a volume 5% H2 / Ar gas flow at 350°C for 2h, with a gas mixture flow rate of 20mL / min and a heating rate of 5°C / min. Pd-Ce catalyst was obtained.

[0064] Comparative Example 5

[0065] The first step is to prepare titanium oxide support material

[0066] Dissolve a known amount of titanium butoxide in 70 mL of ethanol. Stir the mixture in a 70°C water bath until all the ethanol is evaporated. Wash the product with distilled water 3-4 times, dry it in an oven at 90°C for 12 hours, and finally calcine it in a muffle furnace at 400°C for 4 hours, with the heating rate set at 5°C / min. TiO2 is obtained.

[0067] The second step is to prepare the acetylene selective hydrogenation catalyst.

[0068] A certain amount of 0.5g / mL Pd(NO3)2·6H2O solution was added to 50mL deionized water, 0.5g titanium oxide carrier was dispersed in the mixed solution, and 0.25M ammonia water was added dropwise to adjust the pH to 9. After stirring at room temperature for 6 hours, the precipitate was filtered and the catalyst was washed with deionized water 3-4 times. The obtained sample was dried in an oven at 100°C for 8h, and then reduced with a volume 5% H2 / Ar gas flow at 350°C for 2h, with a gas mixture flow rate of 20mL / min and a heating rate of 5°C / min. A Pd-Ti catalyst was obtained.

[0069] The catalysts obtained in the above-mentioned embodiments and comparative examples were characterized by XRD, and the XRD diffraction patterns of six catalyst samples, namely, Pd-Ce1Ti1 (Example 1), Pd-Ce2Ti1 (Comparative Example 1), Pd-Ce10Ti1 (Comparative Example 2), Pd-Ce20Ti1 (Comparative Example 3), Pd-Ce (Comparative Example 4), and Pd-Ti (Comparative Example 5) were shown. It was found that the mesoporous CeO2 sample showed obvious characteristic peaks of (111), (200), (220), (311), (222), (400), and (331) crystal planes at 28.5°, 33.0°, 47.4°, 56.2°, 59.0°, 69.4°, 76.7°, and 79.1°, respectively, proving that the synthesized CeO2 sample has a cubic fluorite structure, and the corresponding PDF card is PDF#34-349. The XRD spectra of the TiO2 samples were compared with the standard card (PDF#21-1272), which proved that the prepared TiO2 samples were mainly in the form of anatase. Ce20Ti1 and Ce10Ti1 samples have diffraction peaks of CeO2, which may be because the TiO2 in these two samples exists in a highly dispersed form on the CeO2 surface. As the TiO2 doping amount in the samples further increases, the characteristic peaks of TiO2 begin to appear in Ce2Ti1 and Ce1Ti1 samples, with an obvious characteristic peak of the (101) face of anatase at 25.3°, and weak characteristic peaks of the corresponding (004), (211) and (204) crystal phases at 37.8°, 55°, and 62.6°, indicating that as the proportion of TiO2 in the composite oxide carrier increases, TiO2 begins to aggregate on the CeO2 surface. Figure 1The XRD patterns of the corresponding composite oxide carriers after loading 0.15% Pd are shown in Table 1. By comparison, no Pd-related characteristic peaks appear in all samples, indicating that Pd is evenly dispersed on the carrier surface or below the detection limit of the instrument.

[0070] The catalytic effect of Pd-Ce1Ti1 catalyst on acetylene hydrogenation reaction is shown in Figure 2 The acetylene conversion rate of the catalyst is shown in Figure 2 , in the range of 60-180℃, the acetylene conversion rate of all catalysts increases with the increase of temperature. When Ce is not added, the acetylene conversion rate of Pd-TiO2 increases from 36% to 90% with the increase of temperature. After adding Ce, the acetylene conversion rate of the catalyst increases. Especially between 60-90℃, the acetylene conversion rate increases from 37% to nearly 100%, which is the largest increase among these catalysts. The order of acetylene conversion rate is:

[0071] Pd-Ce1Ti1>Pd-TiO2>Pd-CeO2>Pd-Ce10Ti1>Pd-Ce2Ti1>Pd-Ce20Ti1.

[0072] from Figure 3 It can be seen that as the temperature increases, the selectivity of acetylene decreases. The effect of the reaction catalyst must simultaneously meet the requirements of high acetylene conversion and high selectivity. The selectivities of Pd-TiO2, Pd-CeO2, Pd-Ce10Ti1, Pd-Ce2Ti1, and Pd-Ce20Ti1 catalysts at 85°C were -127.35%, 85.67.92%, 88.43%, 58.74%, and 87.46%, respectively. Compared with other catalysts, the yield of Pd-Ce1Ti1 catalyst reached 95.34%. Therefore, the CeO2 / TiO2 catalyst with a Ce / Ti mass ratio of 1:1 has good catalytic activity in the selective hydrogenation of acetylene at 85°C.

[0073] The test methods for conversion rate and selectivity are as follows:

[0074] (i) A fixed bed reactor is used as a device for evaluating the catalyst reaction activity, wherein the reaction tube is made of quartz glass;

[0075] (ii) The catalyst of Example 1 was tableted and sieved to select catalyst particles of 40-60 mesh. 0.1 g of the catalyst was weighed and mixed with 0.4 g of quartz sand. The mixture was placed in a quartz tube. The position of the catalyst particles was fixed with quartz wool so that the catalyst was aligned with the position of the thermocouple of the programmable temperature controller. The quartz tube was placed in a fixed bed reactor.

[0076] To be tested;

[0077] (iii) Connect the gas pipeline, use a mass flow meter to control the flow into the reaction system, evacuate the residual air in the reaction pipeline and check for leaks. Before starting the test, use hydrogen to reduce the catalyst at a certain temperature for 1 hour. Use N2 to purge the pipeline when cooling. After cooling to room temperature, introduce the raw gas for activity test.

[0078] (iv) The raw gas is passed through a mass flow meter, a fixed bed reactor and a gas chromatograph in sequence. The corresponding gas cylinders, air generator and hydrogen generator are turned on. The gas chromatograph is turned on, the instrument parameters are adjusted, the temperature of the Porapak-N chromatographic column box is set to 80°C, the temperature of the detector is set to 120°C, the hydrogen flame FID detector is turned on, and ignition is performed.

[0079] (v) At the beginning of the test, the raw gas is passed through the fixed bed reactor. The program of the programmable temperature controller is set and the temperature is raised. When the temperature reaches the reaction temperature, it is maintained for more than 30 minutes. After passing through the fixed bed reactor, the reaction raw gas enters the gas chromatograph for online detection. At the end of the test, the corresponding product peak area is recorded and quantitative analysis is performed.

[0080] (vi) After the test, turn off the reaction raw gas cylinder, gas chromatograph, program temperature controller, air generator and hydrogen generator in sequence.

[0081] In addition, the present invention also provides a table of acetylene conversion and selectivity of several existing catalysts, as shown in Table 1:

[0082] Table 1 Summary of acetylene hydrogenation reaction conditions and acetylene conversion and ethylene selectivity data for different catalysts

[0083]

[0084] As can be seen from the above table, the effects of the catalysts shown in

[27] ,

[31] ,

[28] ,

[34] ,

[35] , and

[36] are also relatively good.

[0085] For the catalyst

[27] , it has an acetylene conversion rate of 100% at 80°C, but the ethylene selectivity is slightly lower, only 68%. The temperature of the present application is between 60-180°C, and at 80°C, it can reach an acetylene conversion rate of nearly 100%, and the ethylene selectivity is close to 100%. In addition, the method of the present invention has the advantages of simple preparation steps, easy availability of raw materials, and safe operation; it also overcomes the problems of low acetylene conversion rate and poor selectivity.

[0086] For the catalyst

[31] , it has an acetylene conversion of 100% and an ethylene selectivity of more than 80% at 80°C, while the temperature of the present application is between 60-180°C, and the selectivity is close to 100% at 85°C.

[0087] For the

[28] th catalyst, it has an acetylene conversion rate of 97% and an ethylene selectivity of more than 89% at 210°C, while the temperature of the present application is between 60-180°C, which can achieve an acetylene conversion rate of 100% and an ethylene selectivity close to 100%.

[0088] For the

[34] th catalyst, it has an acetylene conversion rate of 100% and an ethylene selectivity of more than 90% at 180°C, while the temperature of the present application is between 60-180°C, which can achieve an acetylene conversion rate of 100% and an ethylene selectivity close to 100%.

[0089] For the

[35] th catalyst, it has an acetylene conversion rate of 95% and an ethylene selectivity of more than 95% at 80°C, while the temperature of the present application is 80°C, which can achieve an acetylene conversion rate of nearly 100% and an ethylene selectivity of nearly 100%.

[0090] For the

[36] th catalyst, it has an acetylene conversion rate of 90% and an ethylene selectivity of more than 100% at 200°C, while the temperature of the present application is between 60-180°C, which can achieve an acetylene conversion rate of 100% and an ethylene selectivity close to 100%.

[0091] The implementation modes of the present invention are described in detail above in conjunction with the embodiments, but the present invention is not limited to the above-mentioned implementation modes. For ordinary technicians in this technical field, after knowing the contents recorded in the present invention, they can make several equivalent changes and substitutions thereto without departing from the principle of the present invention, and these equivalent changes and substitutions should also be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for selective hydrogenation of acetylene, characterized in that: The following steps are involved: S1: preparing cerium oxide support material for standby use; S2: preparing a cerium / titanium bimetallic oxide support material for later use; S3: 1-10mL of 0.5g / mL palladium salt solution is added to deionized water, and the cerium / titanium bimetallic oxide support prepared in step S2) is dispersed in the mixed solution to obtain a sample solution, the pH of the sample solution is adjusted to 9-11, uniformly stirred at room temperature, filtered to obtain a precipitate, and then the catalyst is washed with deionized water to obtain a catalyst sample, the obtained sample is dried in an oven, and then reduced with a reducing gas flow at high temperature. The acetylene selective hydrogenation catalyst is obtained.

2. The method for preparing the acetylene selective hydrogenation catalyst according to claim 1, characterized in that: The preparation method of the cerium oxide support material in step S1 is: Deionized water is added to a container, cerium nitrate and urea are weighed and dissolved in a beaker, and stirred until dissolved to obtain a mixed solution; the mixed solution is added to a 100 mL stainless steel autoclave, and the stainless steel autoclave is placed in an oven and maintained at 100-180° C. for 10-24 hours; the stainless steel autoclave is then cooled to room temperature, the mixed solution in the stainless steel autoclave is filtered and washed to obtain a precipitate, and the precipitate is dried at 60-100° C. for 12-24 hours to obtain a solid powder; the obtained solid powder is calcined in a muffle furnace, and the heating rate is set to 5-15° C. / min to obtain a cerium oxide carrier material.

3. The method for preparing the acetylene selective hydrogenation catalyst according to claim 2, characterized in that: The molar ratio of the cerium salt to the urea is 1:1-5.

4. The method for preparing the acetylene selective hydrogenation catalyst according to claim 2, characterized in that: The calcination temperature is 300-800°C; the calcination time is 3-8 hours.

5. The method for preparing the acetylene selective hydrogenation catalyst according to claim 2, characterized in that: The cerium salt is one or a combination of cerium nitrate, cerium acetate, cerium chloride and cerium sulfate.

6. The method for preparing acetylene by selective hydrogenation reaction according to claim 1, characterized in that: The preparation method of the cerium / titanium bimetallic oxide support material in step 2 is: The titanium salt is dissolved in ethanol to obtain a titanium butoxide solution, uncalcined cerium dioxide is added to the titanium butoxide solution to obtain a mixture, and the mixture is stirred in a 70°C water bath until all the ethanol is evaporated to obtain a crude cerium / titanium bimetallic oxide support material. The obtained cerium / titanium bimetallic oxide support material is washed with distilled water 3-4 times, dried in an oven at 100-180°C for 10-24h, and finally calcined in a muffle furnace, and the heating rate is set to 5-15°C / min.

7. The method for preparing the acetylene selective hydrogenation catalyst according to claim 6, characterized in that: The titanium salt includes one or a combination of titanium butoxide, isopropyl titanate, titanium oxysulfate, TiCl4, and TiCl3.

8. The method for preparing the acetylene selective hydrogenation catalyst according to claim 6, characterized in that: The calcination temperature is 300-800°C; the calcination time is 3-8 hours.

9. The method for preparing the acetylene selective hydrogenation catalyst according to claim 1, characterized in that: Step 3: The preparation method of the acetylene selective hydrogenation catalyst is: 0.5g / mL Pd(NO3)2·6H2O solution was added to 50mL deionized water, cerium / titanium bimetallic oxide support was dispersed into the mixed solution, 0.25M ammonia water was added dropwise, and pH was adjusted to 9-11; after stirring at room temperature for 6 hours, the precipitate was obtained by suction filtration, and the catalyst was washed with deionized water 3-4 times. The obtained sample was dried in an oven at 100°C for 8h, and then reduced with 5%-20% H2 / Ar gas flow at 350°C for 2-4h, the gas mixture flow rate was 10-30mL / min, and the heating rate was 5-15°C / min; thus, the acetylene selective hydrogenation catalyst was obtained.

10. The method for preparing the acetylene selective hydrogenation catalyst according to claim 9, characterized in that: The palladium salt is one of palladium nitrate, palladium sulfate, palladium chloride, triphenylphosphine palladium, and palladium acetate.

11. The method for preparing the acetylene selective hydrogenation catalyst according to claim 9, characterized in that: The reduction temperature is 300-500°C; the reduction gas is 5%-20% H2 / Ar gas flow, and the reduction time is 2-4 hours.

12. An acetylene selective hydrogenation reaction catalyst prepared by the preparation method of the acetylene selective hydrogenation reaction catalyst according to claims 1-11, characterized in that: The mass ratio of Ce / Ti in the catalyst is 0-20:1-0.

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