Cu x Fe y Al z Application of multi-component catalysts in the transfer hydrogenation reaction of benzene and ethanol

Abstract

This invention belongs to the field of transfer hydrogenation reaction technology of benzene and ethanol, specifically relating to Cu x Fe y Al z Application of multi-component catalysts in the transfer hydrogenation reaction of benzene and ethanol. Cu x Fe y Al z In the multi-component catalyst, x = 8, 0 < y ≤ 2, and 0 < z ≤ 2. This invention prepares a Cu-Fe-Al ternary catalyst via a simple co-precipitation method, which is then used for the transfer hydrogenation reaction of benzene and ethanol. At 250℃, the conversion rate of benzene is >99% (to cyclohexane), with a selectivity >99%, demonstrating superior catalytic performance and cycle stability. This invention provides an economical and green route for the hydrogenation of benzene to cyclohexane.

Description

Technical Field

[0001] This invention belongs to the field of transfer hydrogenation reaction technology of benzene and ethanol, specifically relating to Cu x Fe y Al z Application of multi-component catalysts in the transfer hydrogenation reaction of benzene and ethanol. Background Technology

[0002] Cyclohexane has a wide range of applications in the petrochemical industry and is an important chemical raw material. Its main economic use is in the production of caprolactam and adipic acid, intermediates in the synthesis of nylon. Cyclohexane can also be used as a flux, serving as an excellent flux for resins, asphalt, waxes, cellulose ethers, and rubber. Except for a small amount obtained by distillation from petroleum fractions, 90% of cyclohexane is derived from the benzene hydrogenation process. Therefore, the production of cyclohexane by benzene hydrogenation has high economic value. Industrially, the commonly used methods for producing cyclohexane by benzene hydrogenation are mainly the gas-phase method and the liquid-phase method. The liquid-phase benzene hydrogenation process requires higher pressure and has a lower conversion rate, resulting in problems such as high energy consumption, high process risk, and low yield. In contrast, the gas-phase benzene hydrogenation process has uniform mixing and easy separation of the catalyst from the product. Both the gas-phase and liquid-phase methods require the use of high-pressure H2 for direct hydrogenation, leading to high costs, stringent storage and transportation requirements, safety risks, and operational limitations.

[0003] Catalytic transfer hydrogenation (CTH) is considered an effective alternative to traditional high-pressure hydrogenation processes due to its high efficiency, atom economy, and sustainability. Reducing solvents such as methanol, ethanol, and isopropanol produced by biorefineries can serve as hydrogen sources. Ethanol is an attractive hydrogen donor due to its abundance, sustainability, non-toxicity, and environmentally friendly properties; however, ethanol is not readily undergoing hydride transfer because the resulting carbocations are highly unstable. Therefore, finding a catalyst that can both dehydrogenate ethanol and hydrogenate the benzene ring is crucial. Summary of the Invention

[0004] To address the problems existing in the current catalytic transfer hydrogenation preparation of cyclohexane, this invention provides a Cu... x Fe y Al z A multi-component catalyst, when used in the transfer hydrogenation reaction of benzene and ethanol, exhibits superior catalytic performance with a benzene conversion rate >99% (to cyclohexane) and a selectivity >99% at 250°C. The catalyst was prepared via a co-precipitation method, and the highly dispersed Cu nanoparticles, relatively high copper surface area, and synergistic effect between copper and iron are key factors in improving the transfer hydrogenation yield. This catalyst is used in the transfer hydrogenation reaction of benzene and ethanol.

[0005] The technical solution of the present invention is as follows:

[0006] Cux Fe y Al z Application of multi-element catalysts in the transfer hydrogenation reaction of benzene and ethanol, where x = 8, 0 < y ≤ 2, 0 < z ≤ 2.

[0007] Preferably, the Cu x Fe y Al z The multi-component catalyst was prepared by co-precipitation.

[0008] Preferably, the catalyst further includes CeO2, i.e., Cu. x Fe y Al z / CeO2; preferably, the molar ratio of Ce to Al is 1-2:1.

[0009] Preferably, the Cu x Fe y Al z The preparation method of a multi-element catalyst includes the following steps:

[0010] (1) Copper salt, iron salt and aluminum salt are mixed evenly to prepare a precursor solution;

[0011] (2) The precursor solution and alkaline precipitant solution from step (1) are simultaneously and slowly added dropwise into the reactor for reaction;

[0012] (3) Washing, drying, calcining; reducing gas reduction treatment, directly used in the transfer hydrogenation reaction of benzene and ethanol.

[0013] Furthermore, in step (1), the molar ratio of copper, iron, and aluminum in the copper salt, iron salt, and aluminum salt is 8:0.5-2:0.5-2.

[0014] Furthermore, the reaction conditions in step (2) are: 70℃-90℃, reaction time for more than 12 hours.

[0015] Furthermore, CeO2 is added before the reaction in step (2).

[0016] Furthermore, the washing conditions in step (3) are to wash with water until the pH of the supernatant is 6-8;

[0017] Furthermore, the calcination conditions in step (3) are calcination at 480℃ for 2-6 hours with a heating rate of 2℃ / min;

[0018] Furthermore, in step (3), the reducing gas reduction process is as follows: under a hydrogen atmosphere, the gas is reduced at a heating rate of 2℃ / min for 2 hours, and the reduction temperature is 200℃.

[0019] Beneficial effects of the present invention

[0020] Currently, catalysts commonly used for ethanol dehydrogenation are mainly Cu-based catalysts, while metals with catalytic activity for benzene hydrogenation include Rh, Pt, W, Ni, Fe, Pd, and Co. This invention prepares a Cu-Fe-Al ternary catalyst via a simple co-precipitation method and applies it to the transfer hydrogenation reaction of benzene and ethanol. At 250℃, the benzene conversion rate is >99% (to cyclohexane), with a selectivity >99%, demonstrating superior catalytic performance and cycle stability. This invention provides an economical and green route for the synthesis of cyclohexane from benzene hydrogenation. Attached Figure Description

[0021] Figure 1 Transmission electron microscopy (TEM) image of the Cu8Fe1Al1 catalyst prepared in Example 1. Detailed Implementation

[0022] Example 1

[0023] Weigh 48.3g of Cu(NO3)2·3H2O, 10.1g of Fe(NO3)3·9H2O, and 9.38g of Al(NO3)3·9H2O, and dissolve them in 400ml of deionized water. Sonicate for 15min to dissolve and form a homogeneous metal ion precursor solution. Then weigh 16g of NaOH and 5.3g of Na2CO3 and dissolve them in 400ml of deionized water to prepare a precipitant solution. Slowly add the metal precursor solution and precipitant solution dropwise to a three-necked flask pre-filled with 400ml of water and stir magnetically for 30min. Heat to 80℃ and age for 12h. Centrifuge the mixture and wash with deionized water until the pH of the supernatant is approximately 7. Then dry in a vacuum drying oven at 80℃ for 20h. Calcine the resulting solid in a muffle furnace at 480℃ for 3h with a heating rate of 2℃ / min. The sample was then placed in a hydrogen atmosphere and reduced at a heating rate of 2℃ / min for 2 hours at a reduction temperature of 200℃. The reduced sample was then used directly as a catalyst. The reduced catalyst was named Cu8Fe1Al1.

[0024] The transfer hydrogenation reaction was carried out in a fixed-bed reactor (quartz reaction tube, ID = 8 mm). 200 mg of catalyst was weighed and pretreated under a H2 gas stream at 350 °C for 2 h. After pretreatment, the reactor was purged with argon gas at a flow rate of 36 mL / min for 30 min to remove residual hydrogen. Then, the reactants (a mixed solution of ethanol and benzene) were pumped into the reactor using a micro-injection pump. The reaction flow rate was 0.04 mL / min, and the space velocity (WHSV) was 13.67 h⁻¹. -1 Product analysis was performed using an online gas chromatograph. Catalyst performance was tested between 200 and 400 °C, with analysis performed after stabilization at 50 °C for 15 minutes. At 250 °C, the conversion rate of benzene was 99.7% (to cyclohexane), with a selectivity of 99.3%.

[0025] Example 2

[0026] Weigh 48.3g of Cu(NO3)2·3H2O, 10.1g of Fe(NO3)3·9H2O, and 9.38g of Al(NO3)3·9H2O, and dissolve them in 400ml of deionized water. Sonicate for 15min to dissolve and form a homogeneous metal ion precursor solution. Then weigh 16g of NaOH and 5.3g of Na2CO3 and dissolve them in 400ml of deionized water to prepare a precipitant solution. Slowly add the metal precursor solution and precipitant solution dropwise to a three-necked flask pre-filled with 400ml of water and stir magnetically for 30min. Heat to 80℃ and age for 12h. Centrifuge the mixture and wash with deionized water until the pH of the supernatant is approximately 7. Then dry in a vacuum drying oven at 80℃ for 20h. Calcine the resulting solid in a muffle furnace at 480℃ for 3h with a heating rate of 2℃ / min. The sample was then placed in a hydrogen atmosphere and reduced at a heating rate of 2℃ / min for 2 hours at a reduction temperature of 200℃. The reduced sample was then used directly as a catalyst. The reduced catalyst was named Cu8Fe1Al1.

[0027] The transfer hydrogenation reaction was carried out in a fixed-bed reactor (quartz reaction tube, ID = 8 mm). 100 mg of catalyst was weighed and pretreated under a H2 gas stream at 350 °C for 2 h. After pretreatment, the tube was purged with argon gas at a flow rate of 36 mL / min for 30 min to remove residual hydrogen. Then, the reactants (a mixed solution of ethanol and benzene) were pumped into the reactor using a micro-injection pump. The reaction flow rate was 0.04 mL / min, and the space velocity (WHSV) was 13.67 h⁻¹. -1 Product analysis was performed using an online gas chromatograph. Catalyst performance was tested between 200 and 400 °C, with analysis performed after stabilization at 50 °C for 15 minutes. At 250 °C, the conversion rate of benzene was 89.6% (to cyclohexane), with a selectivity of 91.2%.

[0028] Example 3

[0029] Weigh 48.3g of Cu(NO3)2·3H2O, 10.1g of Fe(NO3)3·9H2O, and 9.38g of Al(NO3)3·9H2O, and dissolve them in 400ml of deionized water. Sonicate for 15min to dissolve the dissolved substances and form a homogeneous metal ion precursor solution. Then weigh 16g of NaOH and 5.3g of Na2CO3 and dissolve them in 400ml of deionized water to prepare a precipitant solution. The metal precursor solution and precipitant solution were simultaneously and slowly added dropwise to a three-necked flask pre-filled with 400 ml of water and magnetically stirred for 30 min. 4.3 g of CeO2 was then added to the solution, and the mixture was magnetically stirred for another 15 min to obtain a homogeneous suspension. The suspension was heated to 80 °C and aged for 12 h. The mixture was centrifuged and washed with deionized water until the pH of the supernatant was approximately 7. It was then dried in a vacuum drying oven at 80 °C for 20 h. The resulting solid was calcined in a muffle furnace at 480 °C for 3 h at a heating rate of 2 °C / min. The sample was then reduced under a hydrogen atmosphere at a heating rate of 2 °C / min for 2 h at a reduction temperature of 200 °C. The reduced catalyst was then used directly as a catalyst and named Cu8Fe1Al1 / CeO2 (Ce:Al = 1:1).

[0030] The transfer hydrogenation reaction was carried out in a fixed-bed reactor (quartz reaction tube, ID = 8 mm). 200 mg of catalyst was weighed and pretreated under a H2 gas stream at 200 °C for 2 h. After pretreatment, the reactor was purged with argon gas at a flow rate of 36 mL / min for 30 min to remove residual hydrogen. Then, the reactants (a mixed solution of ethanol and benzene) were pumped into the reactor using a micro-injection pump. The reaction flow rate was 0.04 mL / min, and the space velocity (WHSV) was 13.67 h⁻¹. -1 Product analysis was performed using an online gas chromatograph. Catalyst performance was tested between 200 and 400 °C, with analysis performed every 50 °C for 15 minutes after stabilization. At 250 °C, the conversion rate of benzene was 85.2% (to cyclohexane), with a selectivity of 96.1%.

[0031] Example 4

[0032] Weigh 48.3g of Cu(NO3)2·3H2O, 10.1g of Fe(NO3)3·9H2O, and 9.38g of Al(NO3)3·9H2O, and dissolve them in 400ml of deionized water. Sonicate for 15min to dissolve the dissolved substances and form a homogeneous metal ion precursor solution. Then weigh 16g of NaOH and 5.3g of Na2CO3 and dissolve them in 400ml of deionized water to prepare a precipitant solution. The metal precursor solution and precipitant solution were simultaneously and slowly added dropwise to a three-necked flask pre-filled with 400 ml of water and magnetically stirred for 30 min. 8.6 g of CeO2 was then added to the solution, and the mixture was magnetically stirred for another 15 min to obtain a homogeneous suspension. The suspension was heated to 80 °C and aged for 12 h. The mixture was centrifuged and washed with deionized water until the pH of the supernatant was approximately 7. It was then dried in a vacuum drying oven at 80 °C for 20 h. The resulting solid was calcined in a muffle furnace at 480 °C for 3 h at a heating rate of 2 °C / min. The sample was then reduced under a hydrogen atmosphere at a heating rate of 2 °C / min for 2 h at a reduction temperature of 200 °C. The reduced sample was then used directly as a catalyst and named Cu8Fe1Al1 / CeO2 (Ce:Al = 2:1).

[0033] The transfer hydrogenation reaction was carried out in a fixed-bed reactor (quartz reaction tube, ID = 8 mm). 200 mg of catalyst was weighed and pretreated under a H2 gas stream at 200 °C for 2 h. After pretreatment, the reactor was purged with argon gas at a flow rate of 36 mL / min for 30 min to remove residual hydrogen. Then, the reactants (a mixed solution of ethanol and benzene) were pumped into the reactor using a micro-injection pump. The reaction flow rate was 0.04 mL / min, and the space velocity (WHSV) was 13.67 h⁻¹. -1 Product analysis was performed using an online gas chromatograph. Catalyst performance was tested between 200 and 400 °C, with analysis performed after stabilization at 50 °C for 15 minutes. At 250 °C, the conversion rate of benzene was 89.3% (to cyclohexane), with a selectivity of 98.1%.

[0034] Example 5

[0035] Weigh 48.3g of Cu(NO3)2·3H2O, 20.2g of Fe(NO3)3·9H2O, and 9.38g of Al(NO3)3·9H2O, and dissolve them in 400ml of deionized water. Sonicate for 15min to dissolve and form a homogeneous metal ion precursor solution. Then weigh 16g of NaOH and 5.3g of Na2CO3 and dissolve them in 400ml of deionized water to prepare a precipitant solution. Slowly add the metal precursor solution and precipitant solution dropwise to a three-necked flask pre-filled with 400ml of water and stir magnetically for 30min. Heat to 80℃ and age for 12h. Centrifuge the mixture and wash with deionized water until the pH of the supernatant is approximately 7. Then dry in a vacuum drying oven at 80℃ for 20h. Calcine the resulting solid in a muffle furnace at 480℃ for 3h with a heating rate of 2℃ / min. The sample was then placed in a hydrogen atmosphere and reduced at a heating rate of 2℃ / min for 2 hours at a reduction temperature of 200℃. The reduced sample was then used directly as a catalyst. The reduced catalyst was named Cu8Fe2Al1.

[0036] The transfer hydrogenation reaction was carried out in a fixed-bed reactor (quartz reaction tube, ID = 8 mm). 200 mg of catalyst was weighed and pretreated under a H2 gas stream at 350 °C for 2 h. After pretreatment, the reactor was purged with argon gas at a flow rate of 36 mL / min for 30 min to remove residual hydrogen. Then, the reactants (a mixed solution of ethanol and benzene) were pumped into the reactor using a micro-injection pump. The reaction flow rate was 0.04 mL / min, and the space velocity (WHSV) was 13.67 h⁻¹. -1 Product analysis was performed using an online gas chromatograph. Catalyst performance was tested between 200 and 400 °C, with analysis performed after stabilization at 50 °C for 15 minutes. At 250 °C, the conversion rate of benzene was 88.6% (to cyclohexane), with a selectivity of 90.7%.

[0037] Example 6

[0038] Weigh 48.3 g of Cu(NO3)2·3H2O, 5.05 g of Fe(NO3)3·9H2O, and 9.38 g of Al(NO3)3·9H2O, and dissolve them in 400 ml of deionized water. Sonicate for 15 min to dissolve the dissolved substances and form a homogeneous metal ion precursor solution. Then weigh 16 g of NaOH and 5.3 g of Na2CO3 and dissolve them in 400 ml of deionized water to prepare a precipitant solution. Slowly add the metal precursor solution and precipitant solution dropwise to a three-necked flask pre-filled with 400 ml of water and stir magnetically for 30 min. Heat to 80 °C and age for 12 h. Centrifuge the mixture and wash with deionized water until the pH of the supernatant is approximately 7. Then dry in a vacuum drying oven at 80 °C for 20 h. Calcine the resulting solid in a muffle furnace at 480 °C for 3 h with a heating rate of 2 °C / min. The sample was then placed in a hydrogen atmosphere and reduced at a heating rate of 2℃ / min for 2 hours at a reduction temperature of 200℃. The reduced sample was then used directly as a catalyst. The reduced catalyst was named Cu8Fe. 0.5 Al1.

[0039] The transfer hydrogenation reaction was carried out in a fixed-bed reactor (quartz reaction tube, ID = 8 mm). 200 mg of catalyst was weighed and pretreated under a H2 gas stream at 350 °C for 2 h. After pretreatment, the reactor was purged with argon gas at a flow rate of 36 mL / min for 30 min to remove residual hydrogen. Then, the reactants (a mixed solution of ethanol and benzene) were pumped into the reactor using a micro-injection pump. The reaction flow rate was 0.04 mL / min, and the space velocity (WHSV) was 13.67 h⁻¹. -1 Product analysis was performed using an online gas chromatograph. Catalyst performance was tested between 200 and 400 °C, with analysis performed after stabilization at 50 °C for 15 minutes. At 250 °C, the conversion rate of benzene was 91.3% (to cyclohexane), with a selectivity of 94.5%.

[0040] Example 7

[0041] Weigh 48.3g of Cu(NO3)2·3H2O, 10.1g of Fe(NO3)3·9H2O, and 18.76g of Al(NO3)3·9H2O, and dissolve them in 400ml of deionized water. Sonicate for 15min to dissolve and form a homogeneous metal ion precursor solution. Then weigh 16g of NaOH and 5.3g of Na2CO3 and dissolve them in 400ml of deionized water to prepare a precipitant solution. Slowly add the metal precursor solution and precipitant solution dropwise to a three-necked flask pre-filled with 400ml of water and stir magnetically for 30min. Heat to 80℃ and age for 12h. Centrifuge the mixture and wash with deionized water until the pH of the supernatant is approximately 7. Then dry in a vacuum drying oven at 80℃ for 20h. Calcine the obtained solid in a muffle furnace at 480℃ for 3h with a heating rate of 2℃ / min. The sample was then placed in a hydrogen atmosphere and reduced at a heating rate of 2℃ / min for 2 hours at a reduction temperature of 200℃. The reduced sample was then used directly as a catalyst. The reduced catalyst was named Cu8Fe1Al2.

[0042] The transfer hydrogenation reaction was carried out in a fixed-bed reactor (quartz reaction tube, ID = 8 mm). 200 mg of catalyst was weighed and pretreated under a H2 gas stream at 350 °C for 2 h. After pretreatment, the reactor was purged with argon gas at a flow rate of 36 mL / min for 30 min to remove residual hydrogen. Then, the reactants (a mixed solution of ethanol and benzene) were pumped into the reactor using a micro-injection pump. The reaction flow rate was 0.04 mL / min, and the space velocity (WHSV) was 13.67 h⁻¹. -1 Product analysis was performed using an online gas chromatograph. Catalyst performance was tested between 200 and 400 °C, with analysis performed after stabilization at 50 °C for 15 minutes. At 250 °C, the conversion rate of benzene was 89.4% (to cyclohexane), with a selectivity of 73.6%.

[0043] Example 8

[0044] Weigh 48.3g of Cu(NO3)2·3H2O, 10.1g of Fe(NO3)3·9H2O, and 4.69g of Al(NO3)3·9H2O, and dissolve them in 400ml of deionized water. Sonicate for 15min to dissolve and form a homogeneous metal ion precursor solution. Then weigh 16g of NaOH and 5.3g of Na2CO3 and dissolve them in 400ml of deionized water to prepare a precipitant solution. Slowly add the metal precursor solution and precipitant solution dropwise to a three-necked flask pre-filled with 400ml of water and stir magnetically for 30min. Heat to 80℃ and age for 12h. Centrifuge the mixture and wash with deionized water until the pH of the supernatant is approximately 7. Then dry in a vacuum drying oven at 80℃ for 20h. Calcine the resulting solid in a muffle furnace at 480℃ for 3h with a heating rate of 2℃ / min. The sample was then placed in a hydrogen atmosphere and reduced at a heating rate of 2℃ / min for 2 hours at a reduction temperature of 200℃. The reduced sample was then used directly as a catalyst. The reduced catalyst was named Cu8Fe1Al. 0.5 .

[0045] The transfer hydrogenation reaction was carried out in a fixed-bed reactor (quartz reaction tube, ID = 8 mm). 200 mg of catalyst was weighed and pretreated under a H2 gas stream at 350 °C for 2 h. After pretreatment, the reactor was purged with argon gas at a flow rate of 36 mL / min for 30 min to remove residual hydrogen. Then, the reactants (a mixed solution of ethanol and benzene) were pumped into the reactor using a micro-injection pump. The reaction flow rate was 0.04 mL / min, and the space velocity (WHSV) was 13.67 h⁻¹. -1 Product analysis was performed using an online gas chromatograph. Catalyst performance was tested between 200 and 400 °C, with analysis performed after stabilization at 50 °C for 15 minutes. At 250 °C, the conversion rate of benzene was 91.2% (to cyclohexane), with a selectivity of 88.3%.

[0046] Comparative Example 1

[0047] 48.3 g of Cu(NO3)2·3H2O and 9.38 g of Al(NO3)3·9H2O were weighed and dissolved in 400 ml of deionized water. The solution was sonicated for 15 min to form a homogeneous metal ion precursor solution. Then, 16 g of NaOH and 5.3 g of Na2CO3 were weighed and dissolved in 400 ml of deionized water to prepare a precipitant solution. The metal precursor solution and the precipitant solution were simultaneously and slowly added dropwise to a three-necked flask pre-filled with 400 ml of water and magnetically stirred for 30 min. The mixture was heated to 80 °C and aged for 12 h. The mixture was centrifuged and washed with deionized water until the pH of the supernatant was approximately 7. It was then dried in a vacuum drying oven at 80 °C for 20 h. The resulting solid was calcined in a muffle furnace at 480 °C for 3 h at a heating rate of 2 °C / min. The sample was then reduced under a hydrogen atmosphere at a heating rate of 2 °C / min for 2 h at a reduction temperature of 200 °C. The reduced sample was then used directly as a catalyst. The reduced catalyst was named Cu8Fe0Al1.

[0048] The transfer hydrogenation reaction was carried out in a fixed-bed reactor (quartz reaction tube, ID = 8 mm). 200 mg of catalyst was weighed and pretreated under a H2 gas stream at 350 °C for 2 h. After pretreatment, the reactor was purged with argon gas at a flow rate of 36 mL / min for 30 min to remove residual hydrogen. Then, the reactants (a mixed solution of ethanol and benzene) were pumped into the reactor using a micro-injection pump. The reaction flow rate was 0.04 mL / min, and the space velocity (WHSV) was 13.67 h⁻¹. -1 Product analysis was performed using an online gas chromatograph. Catalyst performance was tested between 200 and 400 °C, with analysis performed after stabilization at 50 °C for 15 minutes. At 250 °C, the conversion rate of benzene was 66.7% (to cyclohexane), with a selectivity of 86.8%.

[0049] Comparative Example 2

[0050] 48.3 g of Cu(NO3)2·3H2O and 10.1 g of Fe(NO3)3·9H2O were weighed and dissolved in 400 ml of deionized water. The solution was sonicated for 15 min to form a homogeneous metal ion precursor solution. Then, 16 g of NaOH and 5.3 g of Na2CO3 were weighed and dissolved in 400 ml of deionized water to prepare a precipitant solution. The metal precursor solution and the precipitant solution were simultaneously and slowly added dropwise to a three-necked flask pre-filled with 400 ml of water and magnetically stirred for 30 min. The mixture was heated to 80 °C and aged for 12 h. The mixture was centrifuged and washed with deionized water until the pH of the supernatant was approximately 7. It was then dried in a vacuum drying oven at 80 °C for 20 h. The resulting solid was calcined in a muffle furnace at 480 °C for 3 h at a heating rate of 2 °C / min. The sample was then reduced under a hydrogen atmosphere at a heating rate of 2 °C / min for 2 h at a reduction temperature of 200 °C. The reduced sample was then used directly as a catalyst. The reduced catalyst was named Cu8Fe1Al0.

[0051] The transfer hydrogenation reaction was carried out in a fixed-bed reactor (quartz reaction tube, ID = 8 mm). 200 mg of catalyst was weighed and pretreated under a H2 gas stream at 350 °C for 2 h. After pretreatment, the reactor was purged with argon gas at a flow rate of 36 mL / min for 30 min to remove residual hydrogen. Then, the reactants (a mixed solution of ethanol and benzene) were pumped into the reactor using a micro-injection pump. The reaction flow rate was 0.04 mL / min, and the space velocity (WHSV) was 13.67 h⁻¹. -1 Product analysis was performed using an online gas chromatograph. Catalyst performance was tested between 200 and 400 °C, with analysis performed after stabilization at 50 °C for 15 minutes. At 250 °C, the conversion rate of benzene was 72.1% (to cyclohexane), with a selectivity of 65.4%.

Claims

1. Cu x Fe y Al z Application of multi-component catalysts in the transfer hydrogenation reaction of benzene and ethanol Its characteristic is that: x=8, 0<y≤2, 0<z≤2; The Cu x Fe y Al z The preparation method of a multi-element catalyst includes the following steps: (1) Copper salt, iron salt and aluminum salt are mixed evenly to prepare a precursor solution; (2) The precursor solution and the alkaline precipitant solution from step (1) are simultaneously and slowly added dropwise into the reactor for reaction; (3) Washing, drying, calcining; reducing gas reduction treatment, directly used in the transfer hydrogenation reaction of benzene and ethanol; The calcination conditions for step (3) are: calcination at 480℃ for 2-6 h with a heating rate of 2℃ / min; In step (3), the reducing gas reduction process is as follows: under a hydrogen atmosphere, the gas is reduced at a heating rate of 2℃ / min for 2 hours, and the reduction temperature is 200℃.

2. The application according to claim 1, characterized in that, The catalyst also includes CeO2, i.e., Cu. x Fe y Al z / CeO2.

3. The application according to claim 2, characterized in that, The molar ratio of Ce to Al is 1:

1.

4. The application according to claim 1 or 2, characterized in that, In step (1), the molar ratio of copper, iron, and aluminum in the copper salt, iron salt, and aluminum salt is 8:1:

1.

5. The application according to claim 1 or 2, characterized in that, The reaction conditions in step (2) are: 70℃-90℃, reaction time for more than 12 hours.

6. The application according to claim 2, characterized in that, CeO2 is added before the reaction in step (2).

7. The application according to claim 1 or 1, characterized in that, The washing conditions for step (3) are to wash with high-purity water until the pH of the supernatant is 6-8.

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