Phenylacetylene selective hydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention provides a phenylacetylene selective hydrogenation catalyst and a preparation method and application thereof. The invention discloses a phenylacetylene selective hydrogenation catalyst which comprises the following components in percentage by mass: 8-18% of nickel, 0.5-4% of zinc and the balance of a carrier, wherein the mass of the phenylacetylene selective hydrogenation catalyst is 100%; wherein part of nickel is loaded on the carrier through impregnation, and the remaining nickel and zinc are distributed on the surface layer of the carrier through hydrothermal treatment. The phenylacetylene selective hydrogenation catalyst shows high activity and high selectivity in a phenylacetylene selective hydrogenation reaction, and has the advantage of difficulty in agglomeration after high-temperature reduction.

Description

Technical Field

[0001] The present invention belongs to the field of catalysts, and particularly relates to a catalyst for selective hydrogenation of phenylacetylene, a preparation method thereof, and an application thereof. Background Art

[0002] Styrene (ST) is an important monomer for producing polystyrene, ABS resin, styrene-butadiene rubber, etc. The ethylbenzene dehydrogenation method is the main preparation method, but it has the disadvantage of high production cost. In recent years, with the large-scale production of ethylene, extracting and producing styrene from the by-product C8 fraction of ethylene cracking has become an attractive new way to increase the production of styrene.

[0003] Taking a 1000 kt / a ethylene plant as an example, about 20 - 40 kt of styrene can be obtained annually, and mixed xylene can be recovered at the same time, upgrading the fuel value of the cracked C8 fraction to chemical value. At the same time, due to the separation of the C8 fraction, the load of the subsequent hydrogenation unit for cracked gasoline is reduced, the hydrogen consumption is also reduced, and the poisoning of the hydrogenation catalyst for cracked gasoline caused by styrene polymerization is avoided.

[0004] For the scheme of recovering styrene from cracked gasoline, the currently adopted method is extractive distillation. However, this part of the cracked C8 fraction contains 4000 - 15000 μg·g -1 of phenylacetylene (PA). Since the chemical structures of ST and PA are similar, and their interactions with the extractive distillation solvent are also similar, the effective separation of ST and PA cannot be achieved through the existing extractive distillation process conditions. The presence of these phenylacetylenes will not only increase the consumption of the catalyst during the anionic polymerization of styrene, affect the chain length and polymerization rate, but also affect the color, odor, and comprehensive performance of the polymerization product. Therefore, before extracting styrene from the C8 fraction of ethylene cracking, phenylacetylene must be selectively hydrogenated. Since the C8 fraction contains 25 - 45% of styrene, when hydrogenating phenylacetylene, it is also necessary to minimize the hydrogenation loss of styrene. The content of phenylacetylene and the loss of styrene in the hydrogenation product determine the efficiency of the process for recovering styrene from the C8 fraction of cracked gasoline.

[0005] At present, more than 80% of the styrene selective hydrogenation catalysts industrially applied in styrene extraction units use nickel-based catalysts. The preparation method adopts the conventional equal-volume impregnation method. Before use, it generally needs to be activated at high temperature in flowing hydrogen to reduce NiO to metallic Ni particles, which may cause agglomeration and sintering of Ni particles, resulting in poor stability and selectivity. Therefore, researchers have improved the selective hydrogenation performance of supported Ni-based catalysts by adding promoters and improving the preparation method. To solve this problem, existing patents and literature reports show that, on the one hand, the interaction between the support and the active component is modulated by support modification; on the other hand, the geometric and electronic structures of Ni active sites are modulated by adding promoters such as Zn, Cu, Mg, Co, or Sn to improve the selective hydrogenation performance of the catalyst. Although it has a certain effect in improving the selectivity of styrene, there is still room for improvement, and it is difficult to achieve both high activity and high selectivity.

[0006] CN107954814A relates to a method for the selective hydrogenation of phenylacetylene in a C8 fraction. By using the cracked C8 fraction and hydrogen produced as by-products in the steam cracking process to produce ethylene as raw materials, at a reaction temperature of 10 - 80 °C, a reaction pressure of 0.1 - 2.0 MPa, and a fresh oil volume space velocity of 0.5 - 2.0 h -1 , and a hydrogen / oil volume ratio of 5 - 20:1, the raw materials are contacted with a sulfur-containing catalyst to react, converting the phenylacetylene component in the raw materials into styrene. The sulfur content in the sulfur-containing catalyst is 0.01 - 5% by weight, and the active components of the sulfur-containing catalyst are selected from at least one of metallic nickel, copper, and palladium. However, the poisoning degree of each type of catalyst has a huge impact on the catalyst selectivity, and no detailed description has been made in this regard.

[0007] CN1087892A discloses a method and equipment for purifying phenylacetylene in a styrene stream by a hydrogenation method. By using a mixed gas of nitrogen and hydrogen to reduce the catalyst, using the off-gas from ethylbenzene dehydrogenation to provide hydrogen, and using a multi-stage catalytic reactor to hydrogenate phenylacetylene impurities into styrene. However, the patent only introduces the selective hydrogenation de-acetylene method for a low concentration of phenylacetylene content such as 300 ppm. The phenylacetylene content in the cracked gasoline C8 fraction is usually above 6000 ppm, and the hydrogenation rate of phenylacetylene is about 95%.

[0008] CN101475439A relates to a method for the selective hydrogenation of phenylacetylene using a composite bed in the presence of styrene. By using a hydrocarbon fraction containing phenylacetylene as the raw material, at a reaction temperature of 15 - 100 °C and a weight space velocity of 0.01 - 100 hours -1, under the conditions that the molar ratio of hydrogen to phenylacetylene is 1 - 30:1 and the reaction pressure is -0.08 to 5.0 MPa, the raw materials sequentially pass through a composite bed reactor equipped with catalyst A and catalyst B to contact with the catalysts, and phenylacetylene in the reaction effluent is hydrogenated to styrene. Among them, catalyst A is selected from nickel-based catalysts, catalyst B is selected from at least one of palladium-based or copper-based catalysts, and the loading ratio of catalyst A and catalyst B is 0.5 - 5:1, but there are significant differences in the pretreatment conditions of the two types of composite catalysts.

[0009] CN101475438A relates to a method for the selective hydrogenation of phenylacetylene in the presence of styrene. Using a hydrocarbon fraction containing phenylacetylene as the raw material, at a reaction temperature of 15 - 100 °C and a weight hourly space velocity of 0.01 - 100 h -1 , under the conditions that the molar ratio of hydrogen to phenylacetylene is 1 - 30∶1 and the reaction pressure is -0.08 to 5.0 MPa, the raw materials contact with a carbon oxide-containing catalyst, and phenylacetylene in the reaction effluent is hydrogenated to styrene. The carbon content in the carbon oxide-containing catalyst is 0.02 - 8% by weight of the catalyst, and the carbon oxide-containing catalyst is a catalyst obtained by performing a certain amount of carbon deposition modification on a nickel-based catalyst or a palladium-based catalyst.

[0010] CN108865241A provides a method for the selective hydrogenation and removal of phenylacetylene using a cracked gasoline C8 fraction as the raw material. The C8 fraction is preheated and then enters a fixed-bed hydrogenation reactor, adopting a downward feed mode. The reactor is filled with a catalyst, and the hydrogenation process conditions are: the inlet temperature is 10 - 70 °C, the space velocity is 0.1 - 6.0 h -1 , the pressure is between 0.1 - 2.0 MPa, and the volume ratio of hydrogen to fresh oil is 1 - 100:1; the hydrogenation product is used as the raw material for extracting styrene.

[0011] CN114181032A relates to a method for the selective hydrogenation of phenylacetylene from a C8 fraction, including mixing the C8 fraction with H 2 and then entering an adiabatic reactor. The adiabatic reactor is loaded with a selective hydrogenation catalyst. The volume ratio of hydrogen to the feed at the reactor inlet is 1 - 100:1, the reaction inlet temperature is 20 - 70 °C, the reaction pressure is 0.1 - 1.0 MPa, and the liquid hourly space velocity is 0.1 - 6 h -1 , and the reaction product is cooled and then enters a gas-liquid separation tank for separation; the carrier of the selective hydrogenation catalyst is alumina or mainly alumina, with a bimodal pore size distribution structure, where the pore size of the small pores is 10 - 25 nm and the pore size of the large pores is 50 - 250 nm. The catalyst contains at least Pd, Li, Ni, and Cu. Based on 100% of the mass of the catalyst, the content of Pd is 0.15 - 0.5 wt%, the mass ratio of Li to Pd is 1 - 10:1, the content of Ni is 0.5 - 5 wt%, and the mass ratio of Cu to Ni is 0.1 - 1:1.

[0012] CN102649662A relates to a method for highly selective hydrogenation of phenylacetylene in the presence of styrene. By using a hydrocarbon fraction containing phenylacetylene as a raw material, at a reaction temperature of 15 - 100 °C, a weight hourly space velocity of 0.01 - 100 h -1 , a hydrogen / phenylacetylene molar ratio of 1 - 30:1, and a reaction pressure of -0.08 to 5.0 MPa, the raw material is contacted with a metal oxide catalyst, and phenylacetylene in the reaction effluent is hydrogenated to styrene. Among them, the metal oxide catalyst includes the following components by weight percentage: (a) 2 - 50.0% of metallic nickel or its oxide; (b) 0.05 - 10% of at least one element selected from rare earths or its oxide; (c) 40 - 88% of a carrier.

[0013] CN108212134A relates to a silica-containing boehmite catalyst carrier and its preparation method. The catalyst carrier is a porous material, the porous material is a porous silica-aluminum material, the porous silica-aluminum is nano-sheet-shaped, the silica content is 1 - 20 wt%, the specific surface area is 800 - 1000 m 2 / g, the pore volume is 1.7 - 4.0 cm 3 / g, and the most probable pore diameter is 2 - 30 nm. By regulating the mass ratio of sodium aluminate, aluminum sulfate, and sodium silicate according to the contents of alumina and silica to control the reaction end point, a nano-sheet-shaped silica-containing boehmite catalyst carrier with a large specific surface area and a large pore volume can be prepared. SUMMARY OF THE INVENTION

[0014] In order to solve the above problems, the object of the present invention is to provide a phenylacetylene selective hydrogenation catalyst, its preparation method and application. The phenylacetylene selective hydrogenation catalyst shows high activity and high selectivity in the phenylacetylene selective hydrogenation reaction, and has the advantage of not being easily agglomerated after high-temperature reduction.

[0015] In order to achieve the above object, the present invention provides a phenylacetylene selective hydrogenation catalyst. Calculated based on 100% of the mass of the phenylacetylene selective hydrogenation catalyst, its composition contains 8 - 18% of nickel, 0.5 - 4% of zinc, and the balance is a carrier; among them, part of the nickel is impregnated and loaded on the carrier, and the remaining nickel and zinc are distributed on the surface layer of the carrier through hydrothermal treatment.

[0016] According to a specific embodiment of the present invention, preferably, the composition of the phenylacetylene selective hydrogenation catalyst contains 10 - 15% of nickel and 1 - 2% of zinc.

[0017] According to a specific embodiment of the present invention, preferably, the part of nickel impregnated and loaded on the carrier accounts for 70 - 95 wt% of the total nickel content in the phenylacetylene selective hydrogenation catalyst.

[0018] According to a specific embodiment of the present invention, preferably, the carrier comprises alumina. The alumina used in the catalyst carrier of the present invention can be commercially available alumina, for example, prepared by the nitric acid method, the sulfuric acid method, the carbon dioxide method or currently available methods. It may contain a small amount of conventionally doped silica, titanium oxide, zirconium oxide, etc., but the content does not exceed 5 wt%. This carrier has an appropriate specific surface area and a reasonable pore distribution, and has good activity and stability. The preparation process of the alumina carrier can be a common preparation method. For example, during the preparation of the carrier, alumina powder, water, etc. are kneaded and then extruded into strips or rolled into spheres, dried at 80-120 °C, and calcined at 800-1100 °C for 4-6 hours.

[0019] According to a specific embodiment of the present invention, preferably, the surface layer of the phenylacetylene selective hydrogenation catalyst has a flaky structure.

[0020] According to a specific embodiment of the present invention, preferably, the thickness of the flaky structure is 5-20 nm, and both the width and length are 300-3000 nm.

[0021] According to a specific embodiment of the present invention, preferably, the thickness of the flaky structure is 8-15 nm, and both the width and length are 500-1500 nm.

[0022] According to a specific embodiment of the present invention, preferably, the specific surface area of the phenylacetylene selective hydrogenation catalyst is 70-240 m 2 / g, more preferably 90-160 m 2 / g.

[0023] According to a specific embodiment of the present invention, preferably, the pore volume of the phenylacetylene selective hydrogenation catalyst is 0.25-0.60 cm 3 / g, more preferably 0.35-0.50 cm 3 / g.

[0024] The present invention also provides a method for preparing the above-mentioned phenylacetylene selective hydrogenation catalyst, which comprises the following steps:

[0025] (1) Prepare an aqueous solution of part of the nickel salt and impregnate the carrier. After drying and calcining, a semi-finished catalyst is obtained;

[0026] (2) Dissolve the remaining nickel salt and zinc salt in an alcohol-water mixture, add the semi-finished catalyst obtained in step (1), carry out hydrothermal treatment, and after filtration, washing, drying and calcining, the phenylacetylene selective hydrogenation catalyst is obtained.

[0027] According to a specific embodiment of the present invention, preferably, in the above preparation method, the impregnation in step (1) is equal-volume impregnation.

[0028] According to a specific embodiment of the present invention, preferably, in the above preparation method, the nickel salt includes one or more combinations of nickel sulfate, nickel nitrate, nickel chloride, nickel acetate, and more preferably nickel nitrate and / or nickel acetate.

[0029] According to a specific embodiment of the present invention, preferably, in the above preparation method, the zinc salt includes one or more combinations of zinc nitrate, zinc chloride, zinc sulfate, zinc fluoroborate, or other soluble zinc salts.

[0030] According to a specific embodiment of the present invention, preferably, in the above preparation method, the volume ratio of alcohol to water in the alcohol-water mixture is 4-1:1, and more preferably 2-1:1.

[0031] According to a specific embodiment of the present invention, preferably, in the above preparation method, the alcohol includes one or more combinations of methanol, ethanol, and propanol.

[0032] According to a specific embodiment of the present invention, preferably, in the above preparation method, in steps (1) and (2), the drying temperature is 80-150°C and the drying time is 2-8 h.

[0033] According to a specific embodiment of the present invention, preferably, in the above preparation method, in steps (1) and (2), the calcination temperature is 300-450°C and the calcination time is 3-8 h.

[0034] According to a specific embodiment of the present invention, preferably, in the above preparation method, in step (2), the temperature of the hydrothermal treatment is 100-250°C, and more preferably 120-200°C.

[0035] According to a specific embodiment of the present invention, preferably, in the above preparation method, the time of the hydrothermal treatment is 2-48 h, and more preferably 4-24 h.

[0036] According to a specific embodiment of the present invention, the above preparation method includes the following specific steps:

[0037] (1) Dissolve the nickel salt in water and then impregnate the carrier. The impregnated sample is dried and calcined to obtain a semi-finished catalyst, and the nickel content in the semi-finished catalyst is 70 wt%-95 wt% of the total nickel content of the catalyst;

[0038] (2) Mix water and alcohol in a certain proportion and stir evenly, and then dissolve the nickel salt and zinc salt in the water-alcohol mixed solution and stir until completely dissolved;

[0039] (3) Add the semi-finished catalyst obtained in step (1) into the mixed solution prepared in step (2), stir evenly, then transfer it to a hydrothermal autoclave for hydrothermal treatment, and filter and separate the obtained mixture. Wash, dry, and calcine the obtained solid to obtain the phenylacetylene selective hydrogenation catalyst.

[0040] The hydrothermal treatment adopted in the present invention is the hydrothermal treatment process conditions commonly used for preparing alumina by the hydrothermal method, as recorded in (Contemporary Petrochemical Industry, 2015, 9: 16-22), for example.

[0041] The present invention also provides a method for the selective hydrogenation of phenylacetylene in the presence of styrene. A hydrocarbon fraction containing phenylacetylene is used as a raw material and enters a fixed-bed hydrogenation reactor. The above-mentioned phenylacetylene selective hydrogenation catalyst is loaded in the hydrogenation reactor. The hydrogenation process conditions are: reaction temperature 15-60 °C, volume space velocity 0.1-3 h -1 , the molar ratio of hydrogen to phenylacetylene is 1-10:1, and the reaction pressure is 0-1.0 MPa.

[0042] According to the specific implementation scheme of the present invention, preferably, the hydrogenation process conditions are: reaction temperature 20-45 °C, volume space velocity 0.5-1.5 h -1 , the molar ratio of hydrogen to phenylacetylene is 2-5:1, and the reaction pressure is 0.1-0.5 MPa.

[0043] The present invention uses alumina as a carrier and prepares a nano-sheet Ni-Zn catalyst with a regular surface morphology by hydrothermal method. This catalyst has the advantages of not being easily agglomerated after high-temperature reduction, and at the same time has excellent hydrogenation selectivity. The Ni-Zn catalyst (phenylacetylene selective hydrogenation catalyst) with a regular nano-sheet morphology on its surface. Its surface nano-sheet morphology can not only effectively prevent the aggregation of Ni metal particles during high-temperature calcination and improve the dispersion degree of active components, weaken the strong interaction between Ni and alumina, but also the active site isolation effect takes Zn as a selective promoter, so it shows high activity and high selectivity in the phenylacetylene selective hydrogenation reaction, and has practical application prospects. The method for the selective hydrogenation of phenylacetylene in the presence of styrene provided by the present invention realizes the selective hydrogenation of phenylacetylene under mild process conditions. Description of the Drawings

[0044] Figure 1 SEM image of the leaf-like aggregate structure catalyst obtained in Example 1;

[0045] Figure 2 SEM image of the catalyst in Comparative Example 1. Detailed Description of the Invention

[0046] For a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the following detailed description of the technical solution of the present invention is provided, but it should not be construed as a limitation on the scope of implementation of the present invention. The experimental methods without specific conditions noted in the following examples are generally in accordance with conventional conditions.

[0047] Styrene loss rate = (mass content of styrene in raw material - mass content of styrene in product) * 100% / mass content of styrene in raw material

[0048] Preparation Example 1

[0049] This preparation example provides a catalyst for the selective hydrogenation of phenylacetylene, and its preparation method is as follows:

[0050] (1) Dissolve nickel nitrate in deionized water to make an impregnation solution, then put the carrier alumina into the impregnation solution for impregnation. After the impregnated carrier is dried at 110 °C for 4 h, it is calcined at 380 °C for 4 h to obtain a semi-finished catalyst; the nickel in the semi-finished catalyst accounts for 85% of the total mass of nickel in the catalyst for the selective hydrogenation of phenylacetylene.

[0051] (2) Dissolve nickel nitrate and zinc nitrate in a mixed solution of 70 mL of methanol and water (volume ratio of methanol to water is 7:3), then add the above semi-finished catalyst and stir evenly. Subsequently, transfer it to a high-pressure hydrothermal synthesis kettle and keep it at 150 °C for 12 h. After natural cooling to room temperature, it is filtered, washed, and the sample is dried at 90 °C for 6 h and calcined at 350 °C for 4 h to obtain the catalyst for the selective hydrogenation of phenylacetylene (Catalyst 1). Based on the total mass of the catalyst being 100%, the Ni content in the catalyst is 12 wt%, and the Zn content is 1.5 wt%.

[0052] The above catalyst was subjected to electron microscopy scanning, as Figure 1 shown. Its surface is nano-sheet-like, the average thickness of the leaves is 10 nm, the average width of the leaves is 598 nm, and the average length is 397 nm. The specific surface area of this catalyst is 105 m 2 / g, and the pore volume is 0.41 cm 3 / g.

[0053] Preparation Example 2

[0054] This preparation example provides a catalyst for the selective hydrogenation of phenylacetylene, and its preparation method is as follows:

[0055] (1) Dissolve nickel chloride in deionized water to make an impregnation solution, then put the carrier alumina into the impregnation solution for impregnation. After the impregnated carrier is dried at 120 °C for 3 h, it is calcined at 350 °C for 4.5 h to obtain a semi-finished catalyst; the nickel in the semi-finished catalyst accounts for 70% of the total mass of nickel in the catalyst for the selective hydrogenation of phenylacetylene.

[0056] (2) Dissolve nickel nitrate and zinc sulfate in a mixed solution of 80 mL of absolute ethanol and water (the volume ratio of absolute ethanol to water is 3:2), then add the above-mentioned semi-finished catalyst and stir evenly. Subsequently, transfer it to a high-pressure hydrothermal synthesis kettle and keep it at 160 °C for 9 h. After natural cooling to room temperature, filter and wash it. Dry the sample at 130 °C for 3 h and calcine it at 340 °C for 6 h to obtain a catalyst for selective hydrogenation of phenylacetylene (Catalyst 2). Based on the total mass of the catalyst being 100%, the Ni content in this catalyst is 13.8 wt%, and the Zn content is 0.8 wt%.

[0057] Perform electron microscopy scanning on the above catalyst. Its surface is nano-sheet-like, the average thickness of the leaves is 12 nm, the average width of the leaves is 760 nm, and the average length is 412 nm. The specific surface area of this catalyst is 167 m 2 / g, and the pore volume is 0.55 cm 3 / g.

[0058] Preparation Example 3

[0059] This preparation example provides a catalyst for selective hydrogenation of phenylacetylene, and its preparation method is as follows:

[0060] (1) Dissolve nickel nitrate in deionized water to make an impregnating solution, then put the carrier alumina into the impregnating solution for impregnation. After the impregnated carrier is dried at 140 °C for 2 h, it is calcined at 310 °C for 6 h to obtain a semi-finished catalyst; the nickel in this semi-finished catalyst accounts for 80% of the total mass of nickel in the catalyst for selective hydrogenation of phenylacetylene;

[0061] (2) Dissolve nickel nitrate and zinc fluoroborate in a mixed solution of 68 mL of propanol and water (the volume ratio of propanol to water is 4:1), then add the above-mentioned semi-finished catalyst and stir evenly. Subsequently, transfer it to a high-pressure hydrothermal synthesis kettle and keep it at 170 °C for 7 h. After natural cooling to room temperature, filter and wash it. Dry the sample at 140 °C for 2 h and calcine it at 320 °C for 7 h to obtain a catalyst for selective hydrogenation of phenylacetylene (Catalyst 3). Based on the total mass of the catalyst being 100%, the Ni content in this catalyst is 14 wt%, and the Zn content is 0.5 wt%.

[0062] Perform electron microscopy scanning on the above catalyst. Its surface is nano-sheet-like, the average thickness of the leaves is 7 nm, the average width of the leaves is 485 nm, and the average length is 325 nm. The specific surface area of this catalyst is 101 m 2 / g, and the pore volume is 0.39 cm 3 / g.

[0063] Preparation Example 4

[0064] This preparation example provides a catalyst for selective hydrogenation of phenylacetylene, and its preparation method is as follows:

[0065] (1) Dissolve nickel acetate in deionized water to make an impregnation solution, then put the carrier alumina into the impregnation solution for impregnation. After the impregnated carrier is dried at 100 °C for 5 h, it is calcined at 360 °C for 4.5 h to obtain a semi-finished catalyst; the nickel in the semi-finished catalyst accounts for 90% of the total mass of nickel in the phenylacetylene selective hydrogenation catalyst.

[0066] (2) Dissolve nickel nitrate and zinc nitrate in a mixed solution of 77 mL of absolute ethanol and water (the volume ratio of absolute ethanol to water is 3:1), then add the above semi-finished catalyst and stir evenly. Subsequently, transfer it to a high-pressure hydrothermal synthesis kettle and keep it at 190 °C for 3 h. After natural cooling to room temperature, it is filtered and washed. The sample is dried at 110 °C for 5 h and calcined at 400 °C for 4 h to obtain the phenylacetylene selective hydrogenation catalyst (Catalyst 4). Based on the total mass of the catalyst being 100%, the Ni content in the catalyst is 11.5 wt% and the Zn content is 2 wt%.

[0067] Perform electron microscopy scanning on the above Catalyst C1. Its surface is nano-sheet-like, with an average leaf thickness of 15 nm, an average leaf width of 1437 nm, and an average length of 1192 nm. The specific surface area of this Catalyst C1 is 132 m 2 / g, and the pore volume is 0.47 cm 3 / g.

[0068] Preparation Example 5

[0069] This preparation example provides a phenylacetylene selective hydrogenation catalyst, and its preparation method is as follows:

[0070] (1) Dissolve nickel acetate in deionized water to make an impregnation solution, then put the carrier alumina into the impregnation solution for impregnation. After the impregnated carrier is dried at 110 °C for 3.5 h, it is calcined at 450 °C for 3 h to obtain a semi-finished catalyst; the nickel in the semi-finished catalyst accounts for 95% of the total mass of nickel in the phenylacetylene selective hydrogenation catalyst.

[0071] (2) Dissolve nickel nitrate and zinc fluoroborate in a mixed solution of 65 mL of propanol and water (the volume ratio of absolute ethanol to water is 2:1), then add the above semi-finished catalyst and stir evenly. Subsequently, transfer it to a high-pressure hydrothermal synthesis kettle and keep it at 140 °C for 18 h. After natural cooling to room temperature, it is filtered and washed. The sample is dried at 100 °C for 6 h and calcined at 450 °C for 3 h to obtain the phenylacetylene selective hydrogenation catalyst (Catalyst 5). Based on the total mass of the catalyst being 100%, the Ni content in the catalyst is 10 wt% and the Zn content is 3 wt%.

[0072] The above catalyst was scanned by electron microscopy. Its surface is nanosheet-like, with an average leaf thickness of 17 nm, an average leaf width of 1671 nm, and an average length of 1254 nm. The specific surface area of this catalyst is 89 m 2 / g, and the pore volume is 0.35 cm 3 / g.

[0073] Preparation of Comparative Example 1

[0074] This preparation comparative example provides a comparative catalyst for the selective hydrogenation of phenylacetylene, and its preparation method is as follows:

[0075] Weigh 20 g of a composite support with a weight ratio of alumina to silica of 20:1, add it to a mixed solution of nickel nitrate, lanthanum nitrate, and zinc nitrate, and impregnate it by the equal-volume impregnation method. Dry it at 120 °C for 6 hours and calcine it at 400 °C for 8 hours to obtain a nickel-based catalyst (catalyst D1), such that the nickel content is 12 wt% of the weight of the support, the lanthanum content is 0.8 wt%, and the zinc content is 1.5 wt%.

[0076] The catalyst was scanned by electron microscopy, as Figure 2 shown. It can be seen from Figure 2 that the surface of this catalyst exists in the form of irregular spherical aggregates, and it is prone to agglomeration during high-temperature reduction or long-term evaluation.

[0077] Preparation of Comparative Example 2

[0078] This preparation comparative example provides a comparative catalyst for the selective hydrogenation of phenylacetylene, and its preparation method is as follows:

[0079] Dissolve nickel nitrate and zinc fluoroborate in water to make an impregnation solution, then put the support alumina into this impregnation solution and impregnate it by the equal-volume impregnation method. The impregnated sample was dried at 140 °C for 2 h and calcined at 320 °C for 7 h to obtain the catalyst (catalyst D2). Based on the total mass of the catalyst being 100%, the Ni content in this catalyst is 14 wt% and the Zn content is 0.5 wt%. The specific surface area of this catalyst is 108 m 2 / g, and the pore volume is 0.4 cm 3 / g.

[0080] Preparation of Comparative Example 3

[0081] This preparation comparative example provides a comparative catalyst for the selective hydrogenation of phenylacetylene, and its preparation method is as follows:

[0082] 7.5 g of aluminum nitrate and 6 g of urea were added to 70 mL of deionized water and magnetically stirred for 20 minutes to obtain a colorless transparent solution. Then the solution was transferred to a high-pressure reactor, and hydrogen was introduced to expel the air in the reactor. Then the hydrogen pressure in the reactor was set to 0.5 MPa, and the reactor was sealed. The reactor was heated to 120 °C and reacted for 24 hours. After the reaction, the reactor was naturally cooled to room temperature, the gas in the reactor was discharged, the reactor was opened, and the reaction slurry was collected. The reaction slurry was filtered by suction, and the filtrate was washed repeatedly with deionized water 3 times. Then the filtrate was transferred to an oven at 80 °C and dried for 8 hours to obtain γ-alumina precursor - boehmite. Finally, the boehmite was placed in a muffle furnace and calcined. It was heated from room temperature to 550 °C at a rate of 2 °C / min, held for 6 hours and then naturally cooled to obtain leaf-shaped nano-γ-alumina. The specific surface area of the obtained γ-alumina was 267 m 2 / g, and the average pore diameter was 6.7 nm.

[0083] Then nickel acetate and zinc nitrate were dissolved in deionized water to prepare an impregnation solution, and then the above-mentioned leaf-shaped nano-γ-alumina support was put into the impregnation solution for impregnation. After the impregnated sample was dried at 110 °C for 5 h, it was calcined at 360 °C for 4.5 h to obtain a catalyst (catalyst D3). Based on the total mass of the catalyst being 100%, the Ni content in this catalyst was 11.5 wt%, and the Zn content was 2 wt%.

[0084] Preparation of Comparative Example 4

[0085] This preparation comparative example provides a comparative catalyst for the selective hydrogenation of phenylacetylene, and its preparation method is as follows:

[0086] Nickel nitrate and zinc fluoroborate were dissolved in water to prepare an impregnation solution, and then the carrier alumina was put into the impregnation solution and impregnated by the equal-volume impregnation method. After the impregnated sample was dried at 110 °C for 3.5 h and calcined at 450 °C for 3 h, a catalyst (catalyst D4) was obtained. Based on the total mass of the catalyst being 100%, the Ni content in this catalyst was 10 wt%, and the Zn content was 3 wt%. The specific surface area of this catalyst was 85 m 2 / g, and the pore volume was 0.33 cm 3 / g.

[0087] Catalytic performance evaluation

[0088] Analysis method for raw materials and product composition: An Agilent 7890B gas chromatograph was used to analyze the raw materials and composition.

[0089] Reaction process flow: The C8 fraction was metered by a metering tube and then lifted to the reaction pressure by a plunger pump. After preheating, it was mixed with hydrogen at a constant pressure and entered the catalyst bed from the upper / lower part of the reactor. The reaction product was cooled and then entered a gas-liquid separator for separation. The separated H2 After pressure reduction, it is vented after being measured by a wet gas meter. The liquid is discharged into the product storage tank, and the contents of components such as ST and PA are analyzed by Agilent 7890B gas chromatography.

[0090] Example 1

[0091] Catalyst 1 was loaded into a 500 mL fixed-bed reactor. First, the catalyst was reduced and activated. Under the conditions of a pressure of 2.5 MPa, a bed temperature of 350 °C, and a hydrogen flow rate of 120 L / h, it was maintained for 10 h, and then the temperature was lowered to 30 °C to complete the activation of the catalyst.

[0092] After the activation was completed, a cracked gasoline C8 fraction with 31.47 wt% styrene and 0.87 wt% phenylacetylene was used as the raw material. Using the downward feeding method, at an inlet temperature of 30 °C, a reaction pressure of 0.3 MPa, and a liquid hourly space velocity of 1.0 h -1 and a hydrogen / phenylacetylene molar ratio of 4, it was run for 300 h. The contents of styrene and phenylacetylene in the product were sampled and analyzed every 8 h. The average reaction results were: 0 ppm of phenylacetylene in the product and a styrene loss rate of -1.2%.

[0093] The average reaction results after running for 700 h were: 5 ppm of phenylacetylene in the product and a styrene loss rate of -0.5%, indicating that the catalyst has excellent selectivity and stability.

[0094] Example 2

[0095] Catalyst 2 was loaded into a 100 mL fixed-bed reactor. First, the catalyst was reduced and activated. Under the conditions of a pressure of 2.8 MPa, a bed temperature of 300 °C, and a hydrogen flow rate of 30 L / h, it was maintained for 8 h, and then the temperature was lowered to 27 °C to complete the activation of the catalyst.

[0096] After the activation was completed, a cracked gasoline C8 fraction with 33.56 wt% styrene and 0.75 wt% phenylacetylene was used as the raw material. Using the downward feeding method, at an inlet temperature of 27 °C, a reaction pressure of 0.5 MPa, and a liquid hourly space velocity of 0.8 h -1 and a hydrogen / phenylacetylene molar ratio of 5, it was run for 300 h. The contents of styrene and phenylacetylene in the product were sampled and analyzed every 8 h. The average reaction results were: 4 ppm of phenylacetylene in the product and a styrene loss rate of -0.5%.

[0097] Example 3

[0098] Catalyst 3 was loaded into a 250 mL fixed-bed reactor. First, the catalyst was reduced and activated. Under the conditions of a pressure of 2.0 MPa, a bed temperature of 250 °C, and a hydrogen flow rate of 80 L / h, it was maintained for 6 h, and then the temperature was lowered to 32 °C to complete the activation of the catalyst.

[0099] After the activation is completed, the cracked gasoline C8 fraction with 32.17 wt% styrene and 0.59 wt% phenylacetylene is used as the raw material. In the upward feeding mode, at an inlet temperature of 32 °C, a reaction pressure of 0.1 MPa, and a liquid hourly space velocity of 1.2 h -1 and a hydrogen / phenylacetylene molar ratio of 8, it is run for 300 h. Samples are taken every 8 h to analyze the contents of styrene and phenylacetylene in the product. The average reaction result is: 1 ppm of phenylacetylene in the product and a styrene loss rate of 0.1%.

[0100] Example 4

[0101] The catalyst 4 is loaded into a 500 mL fixed-bed reaction device. First, the reduction activation of the catalyst is carried out. Under the conditions of a pressure of 2.0 MPa, a bed temperature of 320 °C, and a hydrogen flow rate of 150 L / h, it is maintained for 12 h, and then the temperature is lowered to 24 °C to complete the activation of the catalyst.

[0102] After the activation is completed, the cracked gasoline C8 fraction with 32.78 wt% styrene and 0.81 wt% phenylacetylene is used as the raw material. In the downward feeding mode, at an inlet temperature of 24 °C, a reaction pressure of 0.4 MPa, and a liquid hourly space velocity of 0.5 h -1 and a hydrogen / phenylacetylene molar ratio of 2, it is run for 300 h. Samples are taken every 8 h to analyze the contents of styrene and phenylacetylene in the product. The average reaction result is: 8 ppm of phenylacetylene in the product and a styrene loss rate of 0.8%.

[0103] Example 5

[0104] The catalyst 5 is loaded into a 250 mL fixed-bed reaction device. First, the reduction activation of the catalyst is carried out. Under the conditions of a pressure of 1.8 MPa, a bed temperature of 280 °C, and a hydrogen flow rate of 70 L / h, it is maintained for 12 h, and then the temperature is lowered to 24 °C to complete the activation of the catalyst.

[0105] After the activation is completed, the cracked gasoline C8 fraction with 33.14 wt% styrene and 0.64 wt% phenylacetylene is used as the raw material. In the downward feeding mode, at an inlet temperature of 40 °C, a reaction pressure of 0.7 MPa, and a liquid hourly space velocity of 1.5 h -1 and a hydrogen / phenylacetylene molar ratio of 10, it is run for 300 h. Samples are taken every 8 h to analyze the contents of styrene and phenylacetylene in the product. The average reaction result is: 0 ppm of phenylacetylene in the product and a styrene loss rate of 0.3%.

[0106] Comparative Example 1

[0107] The catalyst reduction activation treatment method and evaluation process conditions are the same as those in Example 1, except that catalyst D1 is used. The average reaction result is: 32 ppm of phenylacetylene in the product and a styrene loss rate of 0.2%.

[0108] Average reaction results after 700 h of operation: 65 ppm of phenylacetylene in the product and 1.1% loss rate of styrene.

[0109] Comparative Example 2

[0110] The catalyst reduction and activation treatment method and evaluation process conditions are the same as those in Example 3, except that catalyst D2 is used. The average reaction results are: 21 ppm of phenylacetylene in the product and 0.8% loss rate of styrene.

[0111] Comparative Example 3

[0112] The catalyst reduction and activation treatment method and evaluation process conditions are the same as those in Example 4, except that catalyst D3 is used. The average reaction results are: 47 ppm of phenylacetylene in the product and 0.5% loss rate of styrene.

[0113] Comparative Example 4

[0114] The catalyst reduction and activation treatment method and evaluation process conditions are the same as those in Example 5, except that catalyst D4 is used. The average reaction results are: 13 ppm of phenylacetylene in the product and 1.1% loss rate of styrene.

[0115] It can be seen from the data analysis of the examples and comparative examples that by using the hydrogenation method of the present invention and matching it with the catalyst having a nanosheet-like morphology on the surface of the present invention, the content of phenylacetylene in the hydrogenation product can reach 0 ppm and the styrene shows an increase, which can meet the industrial application conditions for extracting styrene in the subsequent process.

[0116] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the claims of the present invention.

Claims

1. A catalyst for the selective hydrogenation of phenylacetylene. Calculated based on the mass of the catalyst for the selective hydrogenation of phenylacetylene being 100%, its composition comprises 8-18% of nickel, 0.5-4% of zinc, and the balance is the carrier; Among them, Part of the nickel is impregnated and loaded on the carrier, and the remaining nickel and zinc are distributed on the surface layer of the carrier through hydrothermal treatment.

2. The catalyst for the selective hydrogenation of phenylacetylene according to claim 1, Among them, The composition of the catalyst for the selective hydrogenation of phenylacetylene comprises 10-15% of nickel and 1-2% of zinc.

3. The catalyst for the selective hydrogenation of phenylacetylene according to claim 1, Among them, The part of nickel impregnated and loaded on the carrier accounts for 70-95 wt% of the total nickel content in the catalyst for the selective hydrogenation of phenylacetylene.

4. The catalyst for the selective hydrogenation of phenylacetylene according to claim 1, Among them, The carrier includes alumina.

5. The catalyst for the selective hydrogenation of phenylacetylene according to claim 1, Among them, The surface layer of the catalyst for the selective hydrogenation of phenylacetylene has a flaky structure; Preferably, the thickness of the flaky structure is 5-20 nm, and both the width and length are 300-3000 nm; Preferably, the thickness of the flaky structure is 8-15 nm, and both the width and length are 500-1500 nm.

6. The catalyst for the selective hydrogenation of phenylacetylene according to claim 1, Among them, The specific surface area of the phenylacetylene selective hydrogenation catalyst is 70 - 240 m 2 / g, preferably 90 - 160 m 2 / g.

7. The catalyst for the selective hydrogenation of phenylacetylene according to claim 1, Among them, The pore volume of the phenylacetylene selective hydrogenation catalyst is 0.25 - 0.60 cm 3 / g, preferably 0.35 - 0.50 cm 3 / g.

8. A preparation method of the catalyst for the selective hydrogenation of phenylacetylene according to any one of claims 1-7, which comprises the following steps: (1) Prepare an aqueous solution of part of the nickel salt and impregnate the carrier. After drying and calcination, a semi-finished catalyst is obtained; (2) Dissolve the remaining nickel salt and zinc salt in an alcohol-water mixture, add the semi-finished catalyst obtained in step (1), carry out hydrothermal treatment, and after filtration, washing, drying, and calcination, the catalyst for the selective hydrogenation of phenylacetylene is obtained; Preferably, the impregnation in step (1) is equal-volume impregnation.

9. The preparation method according to claim 8, Among them, The nickel salt includes one or a combination of two or more of nickel sulfate, nickel nitrate, nickel chloride, nickel acetate, preferably nickel nitrate and / or nickel acetate.

10. The preparation method according to claim 8, Among them, The zinc salt includes one or a combination of two or more of zinc nitrate, zinc chloride, zinc sulfate, zinc fluoroborate.

11. The preparation method according to claim 8, Among them, The volume ratio of alcohol to water in the alcohol-water mixture is 4-1:1, preferably 2-1:1; Preferably, the alcohol includes one or a combination of two or more of methanol, ethanol, and propanol.

12. The preparation method according to claim 8, Among them, In steps (1) and (2), the drying temperature is 80-150 °C and the drying time is 2-8 h; Preferably, in steps (1) and (2), the calcination temperature is 300-450 °C and the calcination time is 3-8 h.

13. The preparation method according to claim 8, Among them, In step (2), the temperature of the hydrothermal treatment is 100-250 °C, preferably 120-200 °C; Preferably, the time of the hydrothermal treatment is 2-48 h, more preferably 4-24 h.

14. A method for the selective hydrogenation of phenylacetylene in the presence of styrene, wherein a hydrocarbon fraction containing phenylacetylene is used as a raw material and enters a fixed-bed hydrogenation reactor. The hydrogenation reactor is filled with the phenylacetylene selective hydrogenation catalyst according to any one of claims 1-7. The hydrogenation process conditions are as follows: the reaction temperature is 15-60 °C, the volume space velocity is 0.1-3 h -1 , the molar ratio of hydrogen to phenylacetylene is 1-10:1, and the reaction pressure is 0-1.0 MPa.

15. The method for selective hydrogenation of phenylacetylene according to claim 14, wherein, The hydrogenation process conditions are as follows: the reaction temperature is 20 - 45 °C, the volumetric space velocity is 0.5 - 1.5 h -1 , the molar ratio of hydrogen to phenylacetylene is 2 - 5:1, and the reaction pressure is 0.1 - 0.5 MPa.

Images