A catalyst for dehydrogenation of butadiene dimer to ethylbenzene and a preparation method thereof

Abstract

The present application relates to the technical field of catalyst preparation process, in particular to a butadiene dimer dehydrogenation catalyst for preparing ethylbenzene, and a preparation method and application of the catalyst. In view of the defects of the prior art, the present application aims to improve the concentration of high-activity hydroxyl groups on the surface of the catalyst carrier, coat a layer of nano sharp tin type TiO2 on the surface of Al2O3, and the sharp tin type TiO2 can generate high-activity hydroxyl groups under ultraviolet light. At the same time, the additive Sn is added to the Pt-based catalyst, which can modify the defect sites on the surface of the active metal Pt, improve the dispersion of Pt, reduce the adsorption of ethylbenzene products, inhibit the generation of by-products, and achieve the purpose of improving the activity and selectivity of the catalyst. The catalyst has good reaction performance, and under the condition of a reaction temperature of 303-335 DEG C, the conversion rate of butadiene dimer is greater than 90%, the selectivity of ethylbenzene is greater than 92%, and the catalyst has good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, specifically to a catalyst for the dehydrogenation of butadiene dimer to ethylbenzene, as well as the preparation method and application of the catalyst. Background Technology

[0002] Butadiene dimers are byproducts of butadiene extraction units in large petrochemical enterprises, accounting for approximately 1% of total butadiene production. Domestic butadiene units primarily use N,N-dimethylformamide (DMF) as an extractant to purify butadiene products. A small amount of butadiene polymerizes in DMF to form dimers, mainly composed of 4-vinyl-1-cyclohexene. Currently, there are no good utilization pathways for butadiene dimers; they are mainly used as light fuel oil. However, due to their high water content, dehydration treatment is necessary before combustion, otherwise, sudden boiling of the solution will occur, posing a significant safety hazard. Furthermore, they have a strong fishy odor, which can cause significant unpleasant smells during use or long-term storage, harming the health of workers. Ethylbenzene is a raw material for the synthesis of styrene and has a large market demand. Currently, ethylbenzene is mainly prepared through the alkylation of benzene and ethylene. However, due to the high prices of benzene and ethylene, this preparation route is not economically viable. Considering market demand and process safety, dehydrogenating butadiene dimer to produce ethylbenzene can not only improve the utilization value of butadiene dimer, but also provide an economical ethylbenzene synthesis route.

[0003] Butadiene dimer undergoes a dehydrogenation reaction to produce ethylbenzene under the action of a noble metal Pt-based catalyst. This reaction consists of two steps: (1) 4-vinylcyclohexene directly loses four hydrogen atoms on the catalyst surface to produce styrene; (2) the vinyl group in the styrene molecule is added to the catalyst by the removed hydrogen atoms to produce ethylbenzene. Public documents (Petrochemicals, 1995(08):545-548) indicate that using a noble metal Pt-based catalyst can achieve a high conversion rate of butadiene dimer and a high selectivity for ethylbenzene. For example, on a Pt / Al2O3 catalyst, the conversion rate of butadiene dimer can reach 80%, and the selectivity for ethylbenzene remains above 90%.

[0004] However, in existing technologies, Pt-based catalysts operate at relatively high reaction temperatures, and carbon deposits easily form on the catalyst surface, leading to catalyst deactivation. Therefore, developing Pt-based catalysts with high reactivity at lower reaction temperatures has been a key research focus. Pt-based catalysts primarily exert their catalytic effect through hydrogen spillover. The four hydrogen atoms on the cyclohexene in the 4-vinylcyclohexene molecule are first adsorbed onto the Pt surface and then spill over to the hydroxyl groups on the Al2O3 support surface. Therefore, the activity of the hydroxyl groups on the Al2O3 support surface directly affects the hydrogen spillover rate; higher hydroxyl activity results in a faster hydrogen spillover rate. Studies have found that the Al2O3 support surface generally has four types of hydroxyl groups, with the hydroxyl group at the highest stretching vibration frequency having the lowest surface concentration. Therefore, measures can be taken to increase the concentration of highly active hydroxyl groups on the Al2O3 support surface, thereby increasing the hydrogen spillover rate and achieving the goal of improving catalyst activity and lowering the reaction temperature. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to increase the concentration of highly active hydroxyl groups on the catalyst support surface by coating a layer of nano-anatinium-type TiO2 onto the Al2O3 surface. Anatinium-type TiO2 generates highly active hydroxyl groups under ultraviolet light irradiation. Simultaneously, the addition of the promoter Sn to the Pt-based catalyst can modify defect sites on the surface of the active metal Pt, improve Pt dispersion, reduce the adsorption of ethylbenzene products, and inhibit the formation of byproducts, thereby enhancing the catalyst's activity and selectivity.

[0006] The purpose of this invention is to provide a Pt-Sn / Al2O3-TiO2 catalyst with a support surface rich in highly active hydroxyl groups and its preparation method. The Pt mass fraction is 0.2–0.8%, the Sn mass fraction is 0.1–0.4%, the Al2O3 mass fraction is 83.8%–94.8%, and the TiO2 mass fraction is 4.9%–15.0%. Aqueous solutions of chloroplatinic acid, tin tetrachloride, γ-Al2O3, and anatase TiO2 are all commercially available.

[0007] The present invention provides a method for preparing a Pt-Sn / Al2O3-TiO2 catalyst with a support surface rich in highly active hydroxyl groups, comprising the following steps:

[0008] (1) Disperse γ-Al2O3 in nano-anatin type TiO2 hydrosol and dry it with stirring;

[0009] (2) The dried γ-Al2O3 coated with TiO2 was fed into a muffle furnace for calcination;

[0010] (3) The calcined solid was irradiated with ultraviolet light to obtain Al2O3-TiO2 composite support;

[0011] (4) The Al2O3-TiO2 composite support was impregnated in an aqueous solution of chloroplatinic acid and tin tetrachloride in equal volume and dried with stirring;

[0012] (5) The dried solid was fed into a muffle furnace for calcination to obtain PtO2-SnO2 / Al2O3-TiO2;

[0013] (6) PtO2-SnO2 / Al2O3-TiO2 is fed into a tube furnace and reduced with hydrogen to obtain Pt-Sn / Al2O3-TiO2 catalyst.

[0014] The γ-Al2O3 mentioned in step (1) has a specific surface area of ​​120-250 m². 2 / g, spherical particles with a particle size of 0.5 to 2.5 mm;

[0015] The nano-tin-type TiO2 hydrosol described in step (1) has an average particle size of 10-25 nm and a TiO2 content of 5-15%.

[0016] The stirring and drying temperature in step (1) is 80-150℃, and the drying time is 8-15h;

[0017] The muffle furnace roasting temperature in step (2) is 550-650℃, and the roasting time is 4-8h;

[0018] The ultraviolet irradiation time in step (3) is 4 to 10 hours;

[0019] In step (4), the aqueous solution of chloroplatinic acid and tin tetrachloride contains 0.2% to 0.8% Pt and 0.1% to 0.4% Sn by mass.

[0020] The stirring and drying temperature in step (4) is 80-150℃, and the drying time is 8-15h.

[0021] The muffle furnace roasting temperature in step (5) is 550-650℃, and the roasting time is 4-8h;

[0022] The hydrogen reduction temperature in step (6) is 400-600℃, and the reduction time is 4-8h.

[0023] The method for applying the Pt-Sn / Al2O3-TiO2 catalyst with a support surface rich in highly active hydroxyl groups provided by the present invention is as follows: the catalyst is loaded into a reactor, and the catalyst bed is first calcined at 200-250°C with nitrogen gas for 1-3 hours at a flow rate of 10-20 L / (g). catThen, the reactor temperature is raised to 300-320℃. The pumped butadiene dimer feedstock is vaporized and mixed evenly with nitrogen before entering the catalyst bed. The vaporization temperature of the butadiene dimer is 250-300℃, and the volume ratio of butadiene dimer to nitrogen after vaporization is 1:100-1:20. The reaction products are then collected and analyzed using a gas-liquid separator.

[0024] The present invention provides a Pt-Sn / Al2O3-TiO2 catalyst with a support surface rich in highly active hydroxyl groups. Its beneficial effect is that when applied to the dehydrogenation reaction of butadiene dimer to ethylbenzene, it can effectively solve the defects of the prior art. The catalyst has good reaction performance. Under the reaction temperature of 303-335℃, the butadiene dimer conversion rate is greater than 90% and the ethylbenzene selectivity is greater than 92%, which has good prospects for industrial application. Attached Figure Description Detailed Implementation

[0025] The present invention will be further illustrated by the following embodiments, but it should be noted that the following embodiments are only used to further illustrate the content of the invention and do not constitute a limitation on the scope of protection of the present invention.

[0026] Example 1:

[0027] 20g with a specific surface area of ​​120m² 2 / g of γ-Al₂O₃ spherical particles with a particle size of 0.5mm were dispersed in 21.1g of nano-anatinium-type TiO₂ hydrosol with an average particle size of 10nm and a TiO₂ content of 5%. The dispersion was stirred and dried at 80℃ for 15h. The dried γ-Al₂O₃ coated with TiO₂ was first calcined in a muffle furnace at 550℃ for 4h, and then irradiated with ultraviolet light for 4h to obtain an Al₂O₃-TiO₂ composite support with a TiO₂ content of 5%. 20g of the Al₂O₃-TiO₂ support was impregnated in an equal volume of 20.1mL of an aqueous solution of chloroplatinic acid and tin tetrachloride, wherein the mass fraction of Pt in the aqueous solution was 0.2% and the mass fraction of Sn was 0.1%. The impregnation solution was first dried by stirring at 80°C for 15 hours. Then, the dried solid was calcined in a muffle furnace at 550°C for 4 hours. Finally, the calcined solid was reduced with hydrogen at 400°C for 8 hours in a tube furnace to obtain a Pt-Sn / Al2O3-TiO2 catalyst, wherein the mass fraction of Pt was 0.2%, the mass fraction of Sn was 0.1%, the mass fraction of Al2O3 was 94.715%, and the mass fraction of TiO2 was 4.985%.

[0028] Comparative Example 1:

[0029] 20g with a specific surface area of ​​120m² 2 / g of γ-Al₂O₃ spherical particles with a particle size of 0.5mm were impregnated in 20.1mL of an aqueous solution of chloroplatinic acid and tin tetrachloride, wherein the mass fraction of Pt in the aqueous solution was 0.2% and the mass fraction of Sn was 0.1%. The impregnation solution was first dried at 80℃ with stirring for 15h, and then the dried solid was calcined in a muffle furnace at 550℃ for 4h. Finally, the calcined solid was transferred to a tube furnace and reduced with hydrogen at 400℃ for 8h to obtain a Pt-Sn / Al₂O₃ catalyst, wherein the mass fraction of Pt was 0.2%, the mass fraction of Sn was 0.1%, and the mass fraction of Al₂O₃ was 99.7%.

[0030] 10g of catalysts prepared in Example 1 and Comparative Example 1 were respectively loaded into reactors. The catalyst beds were first calcined at 200°C with nitrogen gas for 1 hour at a nitrogen flow rate of 10 L / (g). cat The reactor temperature was then raised to 320°C. The pumped butadiene dimer feedstock was vaporized and mixed evenly with nitrogen before entering the catalyst bed. The vaporization temperature of the butadiene dimer was 250°C, the pumping flow rate of the butadiene dimer was 4.8 g / h, and the volume ratio of butadiene dimer to nitrogen was 1:100. The reaction products were then collected using a gas-liquid separator and analyzed. The results showed that the catalyst prepared in Example 1 achieved a butadiene dimer conversion rate of 94.7% and an ethylbenzene selectivity of 96.3% at a reaction temperature of 326°C. In contrast, the catalyst prepared in Comparative Example 1 achieved a butadiene dimer conversion rate of 83.6% and an ethylbenzene selectivity of 91.2% at a reaction temperature of 321°C.

[0031] Example 2:

[0032] 20g of material with a specific surface area of ​​250m² 2 / g of γ-Al₂O₃ spherical particles with a particle size of 2.5mm were dispersed in 23.5g of nano-anatinium-type TiO₂ hydrosol with an average particle size of 25nm and a TiO₂ content of 15%. The dispersion was stirred and dried at 150℃ for 8h. The dried γ-Al₂O₃ coated with TiO₂ was first calcined in a muffle furnace at 650℃ for 8h, and then irradiated with ultraviolet light for 10h to obtain an Al₂O₃-TiO₂ composite support with a TiO₂ content of 15%. 20g of the Al₂O₃-TiO₂ support was impregnated in 20.2mL of an aqueous solution of chloroplatinic acid and tin tetrachloride, wherein the mass fraction of Pt in the aqueous solution was 0.8% and the mass fraction of Sn was 0.4%. The impregnation solution was first dried by stirring at 150°C for 8 hours. Then, the dried solid was calcined in a muffle furnace at 650°C for 8 hours. Finally, the calcined solid was reduced with hydrogen at 600°C for 4 hours in a tube furnace to obtain a Pt-Sn / Al2O3-TiO2 catalyst, wherein the mass fraction of Pt was 0.8%, the mass fraction of Sn was 0.4%, the mass fraction of Al2O3 was 83.98%, and the mass fraction of TiO2 was 14.82%.

[0033] Comparative Example 2:

[0034] 20g of material with a specific surface area of ​​250m² 2 / g of γ-Al₂O₃ spherical particles with a particle size of 2.5mm were impregnated in 20.2mL of an aqueous solution of chloroplatinic acid and tin tetrachloride, wherein the mass fraction of Pt in the aqueous solution was 0.8% and the mass fraction of Sn was 0.4%. The impregnation solution was first dried at 150℃ with stirring for 8h, and then the dried solid was calcined in a muffle furnace at 650℃ for 8h. Finally, the calcined solid was transferred to a tube furnace and reduced with hydrogen at 600℃ for 4h to obtain a Pt-Sn / Al₂O₃ catalyst, wherein the mass fraction of Pt was 0.8%, the mass fraction of Sn was 0.4%, and the mass fraction of Al₂O₃ was 98.8%.

[0035] 10g of catalysts prepared in Example 2 and Comparative Example 2 were respectively loaded into reactors. The catalyst beds were first calcined at 250°C with nitrogen gas for 3 hours at a nitrogen flow rate of 20 L / (g). catThe reactor temperature was then raised to 300°C. The pumped butadiene dimer feedstock was vaporized and mixed uniformly with nitrogen before entering the catalyst bed. The vaporization temperature of the butadiene dimer was 300°C, the pumping flow rate of the butadiene dimer was 48.3 g / h, and the volume ratio of butadiene dimer to nitrogen was 1:20. The reaction products were then collected using a gas-liquid separator and analyzed. The results showed that the catalyst prepared in Example 2 achieved a butadiene dimer conversion rate of 90.2% and an ethylbenzene selectivity of 98.6% at a reaction temperature of 303°C. In contrast, the catalyst prepared in Comparative Example 2 achieved a butadiene dimer conversion rate of 47.2% and an ethylbenzene selectivity of 96.2% at a reaction temperature of 300°C.

[0036] Example 3:

[0037] 20g with a specific surface area of ​​210m² 2 / g of γ-Al₂O₃ spherical particles with a particle size of 1.0 mm were dispersed in 21.0g of nano-anatinium-type TiO₂ hydrosol with an average particle size of 17 nm and a TiO₂ content of 13%. The dispersion was stirred and dried at 120℃ for 10 h. The dried γ-Al₂O₃ coated with TiO₂ was first calcined in a muffle furnace at 600℃ for 6 h, and then irradiated with ultraviolet light for 6 h to obtain an Al₂O₃-TiO₂ composite support with a TiO₂ content of 12%. 20g of the Al₂O₃-TiO₂ support was impregnated in 20.2mL of an aqueous solution of chloroplatinic acid and tin tetrachloride, wherein the mass fraction of Pt in the aqueous solution was 0.6% and the mass fraction of Sn was 0.3%. The impregnation solution was first dried by stirring at 120℃ for 10 hours. Then, the dried solid was first calcined in a muffle furnace at 600℃ for 6 hours. Finally, the calcined solid was sent to a tube furnace and reduced with hydrogen at 500℃ for 6 hours to obtain a Pt-Sn / Al2O3-TiO2 catalyst, wherein the mass fraction of Pt was 0.6%, the mass fraction of Sn was 0.3%, the mass fraction of Al2O3 was 87.208%, and the mass fraction of TiO2 was 11.892%.

[0038] Comparative Example 3:

[0039] 20g with a specific surface area of ​​210m² 2 / g of γ-Al₂O₃ spherical particles with a particle size of 1.0 mm were impregnated in 20.2 mL of an aqueous solution of chloroplatinic acid and tin tetrachloride, wherein the mass fraction of Pt in the aqueous solution was 0.6% and the mass fraction of Sn was 0.3%. The impregnation solution was first dried at 120 °C with stirring for 10 h, and then the dried solid was calcined in a muffle furnace at 600 °C for 6 h. Finally, the calcined solid was transferred to a tube furnace and reduced with hydrogen at 500 °C for 6 h to obtain a Pt-Sn / Al₂O₃ catalyst, wherein the mass fraction of Pt was 0.6%, the mass fraction of Sn was 0.3%, and the mass fraction of Al₂O₃ was 99.1%.

[0040] 10g of catalysts prepared in Example 3 and Comparative Example 3 were respectively loaded into reactors. The catalyst beds were first calcined at 200°C with nitrogen gas for 2 hours at a nitrogen flow rate of 13 L / (g). cat The reactor temperature was then raised to 320°C. The pumped butadiene dimer feedstock was vaporized and mixed evenly with nitrogen before entering the catalyst bed. The vaporization temperature of the butadiene dimer was 280°C, the pumping flow rate of the butadiene dimer was 10.5 g / h, and the volume ratio of butadiene dimer to nitrogen was 1:60. The reaction products were then collected using a gas-liquid separator and analyzed. The results showed that the catalyst prepared in Example 3 achieved a butadiene dimer conversion rate of 98.7% and an ethylbenzene selectivity of 97.2% at a reaction temperature of 330°C. In contrast, the catalyst prepared in Comparative Example 3 achieved a butadiene dimer conversion rate of 88.6% and an ethylbenzene selectivity of 93.1% at a reaction temperature of 324°C.

[0041] Example 4:

[0042] 20 g of the Al₂O₃-TiO₂ support prepared in Example 3 was impregnated in 20.2 mL of an aqueous solution of chloroplatinic acid and tin tetrachloride, wherein the mass fraction of Pt in the aqueous solution was 0.8% and the mass fraction of Sn was 0.1%. The impregnation solution was first dried at 120 °C with stirring for 10 h, and then the dried solid was calcined in a muffle furnace at 600 °C for 6 h. Finally, the calcined solid was transferred to a tube furnace and reduced with hydrogen at 500 °C for 6 h to obtain a Pt-Sn / Al₂O₃-TiO₂ catalyst, wherein the mass fraction of Pt was 0.8%, the mass fraction of Sn was 0.1%, the mass fraction of Al₂O₃ was 87.208%, and the mass fraction of TiO₂ was 11.892%.

[0043] The catalyst prepared in Example 4 was evaluated under the same reaction conditions as the catalyst prepared in Example 3. The results showed that the catalyst prepared in Example 4 had a butadiene dimer conversion rate of 95.7% and an ethylbenzene selectivity of 92.2% at a reaction temperature of 327°C.

[0044] Example 5:

[0045] 20 g of the Al₂O₃-TiO₂ support prepared in Example 3 was impregnated in 20.1 mL of an aqueous solution of chloroplatinic acid and tin tetrachloride, wherein the mass fraction of Pt in the aqueous solution was 0.2% and the mass fraction of Sn was 0.4%. The impregnation solution was first dried by stirring at 120 °C for 10 h, and then the dried solid was calcined in a muffle furnace at 600 °C for 6 h. Finally, the calcined solid was reduced with hydrogen at 500 °C for 6 h in a tube furnace to obtain a Pt-Sn / Al₂O₃-TiO₂ catalyst, wherein the mass fraction of Pt was 0.2%, the mass fraction of Sn was 0.4%, the mass fraction of Al₂O₃ was 87.472%, and the mass fraction of TiO₂ was 11.928%.

[0046] The catalyst prepared in Example 5 was evaluated under the same reaction conditions as the catalyst prepared in Example 3. The results showed that the catalyst prepared in Example 5 had a butadiene dimer conversion rate of 91.7% and an ethylbenzene selectivity of 92.3% at a reaction temperature of 321°C.

[0047] Example 6:

[0048] 20 g of the Al₂O₃-TiO₂ support prepared in Example 1 was impregnated in 20.2 mL of an aqueous solution of chloroplatinic acid and tin tetrachloride, wherein the mass fraction of Pt in the aqueous solution was 0.6% and the mass fraction of Sn was 0.3%. The impregnation solution was first dried by stirring at 120 °C for 10 h, and then the dried solid was calcined in a muffle furnace at 600 °C for 6 h. Finally, the calcined solid was reduced with hydrogen at 500 °C for 6 h in a tube furnace to obtain a Pt-Sn / Al₂O₃-TiO₂ catalyst, wherein the mass fraction of Pt was 0.6%, the mass fraction of Sn was 0.3%, the mass fraction of Al₂O₃ was 94.145%, and the mass fraction of TiO₂ was 4.955%.

[0049] The catalyst prepared in Example 6 was evaluated under the same reaction conditions as the catalyst prepared in Example 3. The results showed that the catalyst prepared in Example 6 had a butadiene dimer conversion rate of 92.6% and an ethylbenzene selectivity of 95.1% at a reaction temperature of 326°C.

[0050] Example 7:

[0051] 20 g of the Al₂O₃-TiO₂ support prepared in Example 2 was impregnated in 20.2 mL of an aqueous solution of chloroplatinic acid and tin tetrachloride, wherein the mass fraction of Pt in the aqueous solution was 0.6% and the mass fraction of Sn was 0.3%. The impregnation solution was first dried at 120 °C with stirring for 10 h, and then the dried solid was calcined in a muffle furnace at 600 °C for 6 h. Finally, the calcined solid was transferred to a tube furnace and reduced with hydrogen at 500 °C for 6 h to obtain a Pt-Sn / Al₂O₃-TiO₂ catalyst, wherein the mass fraction of Pt was 0.6%, the mass fraction of Sn was 0.3%, the mass fraction of Al₂O₃ was 84.235%, and the mass fraction of TiO₂ was 14.865%.

[0052] The catalyst prepared in Example 7 was evaluated under the same reaction conditions as the catalyst prepared in Example 3. The results showed that the catalyst prepared in Example 7 had a butadiene dimer conversion rate of 90.7% and an ethylbenzene selectivity of 96.3% at a reaction temperature of 323°C.

[0053] Example 8:

[0054] 10g of the catalyst prepared in Example 3 was loaded into a reactor. The catalyst bed was first calcined at 200°C with nitrogen gas for 2 hours at a flow rate of 13 L / (g). cat The reactor temperature was then raised to 310°C. The pumped butadiene dimer feedstock was vaporized and mixed uniformly with nitrogen before entering the catalyst bed. The vaporization temperature of the butadiene dimer was 280°C, the pumping flow rate of the butadiene dimer was 10.5 g / h, and the volume ratio of butadiene dimer to nitrogen was 1:60. The reaction products were then collected using a gas-liquid separator and analyzed. The results showed that the catalyst prepared in Example 3 achieved a butadiene dimer conversion rate of 94.6% and an ethylbenzene selectivity of 96.1% at a reaction temperature of 314°C.

[0055] Example 9:

[0056] 10g of the catalyst prepared in Example 3 was loaded into a reactor. The catalyst bed was first calcined at 200°C with nitrogen gas for 2 hours at a flow rate of 13 L / (g). cat The reactor temperature was then increased to 330°C. The pumped butadiene dimer feedstock was vaporized and mixed uniformly with nitrogen before entering the catalyst bed. The vaporization temperature of the butadiene dimer was 280°C, the pumping flow rate of the butadiene dimer was 10.5 g / h, and the volume ratio of butadiene dimer to nitrogen was 1:60. The reaction products were then collected using a gas-liquid separator and analyzed. The results showed that the catalyst prepared in Example 3 achieved a butadiene dimer conversion rate of 99.1% and an ethylbenzene selectivity of 93.1% at a reaction temperature of 335°C.

[0057] Example 10:

[0058] 10g of the catalyst prepared in Example 3 was loaded into a reactor. The catalyst bed was first calcined at 200°C with nitrogen gas for 2 hours at a flow rate of 18 L / (g). cat The reactor temperature was then raised to 320°C. The pumped butadiene dimer feedstock was vaporized and mixed evenly with nitrogen before entering the catalyst bed. The vaporization temperature of the butadiene dimer was 280°C, the pumping flow rate of the butadiene dimer was 10.5 g / h, and the volume ratio of butadiene dimer to nitrogen was 1:83.1. The reaction products were then collected using a gas-liquid separator and analyzed. The results showed that the catalyst prepared in Example 3 achieved a butadiene dimer conversion rate of 91.7% and an ethylbenzene selectivity of 97.2% at a reaction temperature of 326°C.

[0059] Example 11:

[0060] 10g of the catalyst prepared in Example 3 was loaded into a reactor. The catalyst bed was first calcined at 200°C with nitrogen gas for 2 hours at a flow rate of 10 L / (g). cat The reactor temperature was then raised to 320°C. The pumped butadiene dimer feedstock was vaporized and mixed uniformly with nitrogen before entering the catalyst bed. The vaporization temperature of the butadiene dimer was 280°C, the pumping flow rate of the butadiene dimer was 10.5 g / h, and the volume ratio of butadiene dimer to nitrogen was 1:46.2. The reaction products were then collected using a gas-liquid separator and analyzed. The results showed that the catalyst prepared in Example 3 achieved a butadiene dimer conversion rate of 99.3% and an ethylbenzene selectivity of 92.3% at a reaction temperature of 333°C.

Claims

1. A method for preparing a Pt-Sn / Al2O3-TiO2 catalyst, characterized in that, the Pt-Sn / Al2O3-TiO2 catalyst is a composite carrier of Al2O3-TiO2 as a catalyst, and Pt and Sn are loaded on the composite carrier; the mass fraction of Pt in the Pt-Sn / Al2O3-TiO2 catalyst is 0.2-0.8%, the mass fraction of Sn is 0.1-0.4%, the mass fraction of Al2O3 is 83.8-94.8%, and the mass fraction of TiO2 is 4.9-15.0%; the preparation steps are as follows: (1) dispersing γ-Al2O3 in a nano-anatase TiO2 hydrosol; (2) drying the γ-Al2O3 coated with TiO2, and then calcining the γ-Al2O3; (3) irradiating the calcined solid with ultraviolet light to obtain an Al2O3-TiO2 composite carrier; (4) immersing the Al2O3-TiO2 composite carrier in a solution of platinum salt and tin salt; (5) drying the obtained solid, and then calcining the solid to obtain PtO2-SnO2 / Al2O3-TiO2; and (6) reducing the obtained PtO2-SnO2 / Al2O3-TiO2 to obtain a Pt-Sn / Al2O3-TiO2 catalyst.

2. The method according to claim 1, characterized in that, the mass fraction of the Al2O3-TiO2 composite carrier is 98.8-99.7%, and the mass fraction of TiO2 is 5-15% of the Al2O3-TiO2 composite carrier.

3. The method according to claim 1, characterized in that, the mass fraction of Pt in the catalyst is 0.6%, the mass fraction of Sn is 0.3%, the mass fraction of Al2O3 is 87.2%, and the mass fraction of TiO2 is 11.8%; or the mass fraction of Pt in the catalyst is 0.2%, the mass fraction of Sn is 0.4%, the mass fraction of Al2O3 is 87.5%, and the mass fraction of TiO2 is 11.9%.

4. The method according to any one of claims 1-3, characterized in that, in step (1), the γ-Al2O3 has a specific surface area of 120-250 m2 / g and a particle size of 0.5-2.5 mm, and the nano-anatase TiO2 hydrosol has an average particle size of 10-25 nm and a TiO2 content of 5-15%.

5. The method according to any one of claims 1-3, characterized in that, in step (4), the mass fraction of Pt in the aqueous solution of platinum salt and tin salt is 0.2-0.8%, and the mass fraction of Sn is 0.1-0.4%.

6. The method according to any one of claims 1-3, characterized in that, in steps (2) and (5), the calcination temperature is 550-650°C, and the calcination time is 4-8 h.

7. The method according to any one of claims 1-3, characterized in that, in step (3), the ultraviolet light irradiation time is 4-10 h.

8. The method according to any one of claims 1-3, characterized in that, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The process for reducing PtO2-SnO2 / Al2O3-TiO2 in step (6) is reduced by hydrogen, the hydrogen temperature is 400-600 DEG C, and the reduction time is 4-8h.

9. Use of a catalyst prepared according to the process of any one of claims 1 to 8, characterized in that It is used in the reaction of dehydrogenation of butadiene dimer to produce ethylbenzene.