High-dispersion nickel-based catalyst as well as preparation method and application thereof

Abstract

The invention relates to a high-dispersion nickel-based catalyst as well as a preparation method and application thereof. The high-dispersion nickel-based catalyst consists of a metal nickel active component and a cerium dioxide carrier, wherein the metal nickel is loaded on the cerium dioxide carrier by adopting a sol-gel method. A complexing agent is added into a metal salt solution to form a metal organic complex, so that the dispersion of active components is facilitated, the active metal Ni is highly dispersed in crystal lattices of a carrier cerium oxide, and the Ni-based catalyst with small particle size and high stability is obtained. The interface effect between the high-dispersion Ni nanoparticles and the adjacent cerium oxide carrier promotes the activation of H2 and CO2 molecules, and the Ni / CeO2 catalyst shows excellent catalytic activity, product selectivity and high-temperature stability. In the catalyst, the metal loading capacity can be adjusted in a large range by changing the proportion of the precursor, high dispersion and stability are kept, and large-scale industrial application is expected to be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a highly dispersed nickel-based catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous development of the industrialization process, carbon emissions have been increasing year by year, and the climate and environmental problems brought about by carbon dioxide emissions have become increasingly serious, attracting more and more extensive attention. Utilizing carbon dioxide resourcefully and converting it into high-value industrial products. The carbon dioxide hydrogenation methanation reaction provides an effective way for the resource utilization of CO2. However, due to the influence of thermodynamics and kinetics, there are still great challenges in developing catalysts with both high activity at low temperatures and high stability at high temperatures.

[0003] Currently, supported metal catalysts are usually used for the CO2 hydrogenation reaction, mainly using Group VIII metals (such as Co, Ni, Ru, Rh, Pd, Pt, etc.) as active components and oxides (such as CeO2, Al2O3, TiO2, SiO2, ZrO2, etc.) as carriers. Noble metal catalysts such as Ru have high reaction activity and stability, but due to their high cost, it is difficult to be applied on a large scale. Ni, as a non-noble metal, has attracted much attention due to its good catalytic activity. Ye et al. prepared Ni-based catalysts with three different carriers (SiO2, Al2O3, ZrO2), and it was found that Ni / ZrO2 had the optimal catalytic activity, and the CO2 conversion rate and CH4 selectivity reached 84.0% and 98.6% respectively at 230 °C (Angew. Chem. Int. Ed. 2024, 63, 17669–17680). Cárdenas-Arenas et al. compared the reaction activities of Ni / CeO2 and Ni / Al2O3 and found that Ni / CeO2 had more excellent reaction performance. CeO2 could provide more oxygen vacancies for the activation of CO2 molecules, and an appropriate strong metal-support interaction occurred between Ni and CeO2 to promote the carbon dioxide hydrogenation reaction (Appl. Catal., B, 2020, 265, 118538).

[0004] Ni / CeO2 has attracted much attention among carbon dioxide hydrogenation catalysts due to its high catalytic activity and low price. Currently, common preparation methods for supported catalysts (such as impregnation method, co-precipitation method, etc.) usually show phenomena such as uneven dispersion of active metals and large particle sizes of the generated metal particles when preparing high-loading nickel-based catalysts, resulting in a decrease in catalyst activity. Ni particles also have problems such as easy sintering and agglomeration and poor stability during the reaction process. Therefore, it is of great value to develop Ni-based catalysts with both high activity and high temperature stability by using a suitable preparation method. Summary of the Invention

[0005] The object of the present invention is to provide a highly dispersed nickel-based catalyst, a preparation method thereof and an application thereof. In this catalyst, metallic nickel is highly dispersed, and it has the characteristics of high activity, high selectivity for methane products and high stability.

[0006] The object of the present invention is to provide a preparation method of a highly dispersed nickel-based catalyst, and this method has the characteristics of easy operation, strong repeatability and high universality.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] The present invention provides a preparation method of a highly dispersed nickel-based catalyst. This preparation method includes: dissolving a nickel salt precursor and a cerium salt precursor in deionized water, then adding a complexing agent, and stirring for 0.5 - 4 h until evenly mixed to obtain a mixed solution; performing water bath heating on the mixed solution, where the temperature of the water bath heating is 50 - 85 °C to obtain a sol; placing the sol in a temperature environment of 60 - 150 °C and drying for 6 - 24 h to obtain a gel; wherein, through the water bath heating treatment, a sol with preliminary water removal is obtained, and through the drying treatment, a gel with complete water removal is obtained. Grinding the gel to obtain a powder; first heating at a heating rate of 1 - 5 °C / min -1 to 200 - 300 °C and calcining for 2 - 8 h, and then heating at a heating rate of 1 - 10 °C / min -1 to 400 - 600 °C and continuing to calcine for 2 - 8 h. Using the above operation parameters to perform staged calcination on the powder to obtain the highly dispersed nickel-based catalyst, denoted as the Ni / CeO2 catalyst.

[0009] Furthermore, the nickel salt precursor includes one or more of Ni(NO3)2·6H2O, NiCl2·6H2O, NiSO4·6H2O, Ni(Ac)2·4H2O; the cerium salt precursor includes one or more of Ce(NO3)3·6H2O, CeCl3·7H2O, Ce(Ac)3·xH2O; the complexing agent includes one or more of citric acid, ethylenediaminetetraacetic acid, glycine, polyacrylic acid.

[0010] Furthermore, the molar ratio of the cerium salt precursor as the cerium source to the complexing agent is 1:1 - 3:1.

[0011] Furthermore: the water bath temperature is 60 - 80 °C; the drying temperature is 80 - 120 °C, and the time is 8 - 12 h.

[0012] Furthermore: the operation parameters of the staged calcination specifically include: first heating at a heating rate of 1 - 3 °C / min -1 to 200 - 300 °C and calcining for 4 - 6 h, and then heating at a heating rate of 2 - 5 °C / min -1Heat it up to 400 - 600 °C and continue to calcine for 4 - 6 h.

[0013] The present invention also provides a highly dispersed nickel-based catalyst prepared by the preparation method of the highly dispersed nickel-based catalyst as described above.

[0014] Furthermore: the catalyst includes active metal Ni and CeO2 as a carrier; wherein, the content of the active metal Ni is 1 wt% - 50 wt%, and the content of CeO2 is 50 wt% - 99 wt%; preferably, the content of the active metal Ni is 5 wt% - 20 wt%.

[0015] The present invention also provides the application of the highly dispersed nickel-based catalyst as described above in the reaction of hydrogenating carbon dioxide to methane.

[0016] Furthermore, the application method in the reaction of hydrogenating carbon dioxide to methane includes: performing in-situ reduction pretreatment on the highly dispersed nickel-based catalyst before the reaction; in the in-situ reduction pretreatment, the reduction temperature is 300 - 600 °C, preferably 400 - 500 °C; the reduction atmosphere is high-purity H2 or one or more of inert gases such as N2, Ar, and He.

[0017] Furthermore, after the in-situ reduction pretreatment, it also includes performing catalyst reaction evaluation on the highly dispersed nickel-based catalyst; in the catalyst reaction evaluation, an atmospheric-pressure quartz tube fixed-bed reactor is used, and the reaction temperature is 200 - 400 °C; the molar ratio of H2 to CO2 in the feed gas is 0.5 - 6, preferably 2 - 4; the gas hourly space velocity is 6000 - 120000 mL h - 1 g cat -1 , preferably 12000 - 90000 mL h -1 g cat -1 . Among them, the feed gas is the reaction gas filled in the atmospheric-pressure quartz tube fixed-bed reactor.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] The highly dispersed nickel-based catalyst of the present invention is composed of a metal nickel active component and a cerium dioxide support. The metal nickel is loaded onto the cerium oxide support by using the sol-gel method. By adding a complexing agent to the metal salt solution, a metal-organic complex is formed, which is beneficial to the dispersion of the active component, enabling the active metal Ni to be highly dispersed in the lattice of the cerium oxide support, thereby obtaining a Ni-based catalyst with small particle size and high stability. The interfacial effect between the highly dispersed Ni nanoparticles and the adjacent cerium oxide support promotes the activation of H2 and CO2 molecules, and the Ni / CeO2 catalyst exhibits excellent catalytic activity, product selectivity, and high-temperature stability. In the catalyst of the present invention, the metal loading amount can be adjusted within a wide range by changing the precursor ratio and maintaining high dispersion and stability.

[0020] 1) The highly dispersed nickel-based catalyst provided by the present invention has small Ni nanoparticle size, uniform dispersion, high metal utilization rate, and effectively reduces the preparation cost of the catalyst.

[0021] 2) The preparation method of the highly dispersed nickel-based catalyst provided by the present invention is simple in operation, reliable in method, and has a large adjustable range of metal loading amount, which is beneficial to large-scale production and use.

[0022] 3) The highly dispersed nickel-based catalyst provided by the present invention is used for the methanation reaction of carbon dioxide hydrogenation, has high reaction activity, high selectivity for methane products, and the catalyst has excellent stability. Description of the Drawings

[0023] Figure 1 It is a graph for evaluating the carbon dioxide reaction performance of the catalysts in Examples 1 to 4 of the present invention (reaction conditions: atmospheric pressure, 200 - 400 °C, GHSV = 60000 mL h -1 g cat -1 );

[0024] Figure 2 It is a graph for evaluating the carbon dioxide reaction performance of the catalysts in Example 3, Comparative Examples 1 and 2 of the present invention (reaction conditions: atmospheric pressure, 200 - 400 °C, GHSV = 60000 mL h -1 g cat -1 );

[0025] Figure 3 It is the X-ray diffraction (XRD) pattern of the catalysts in Examples 1 to 4 of the present invention;

[0026] Figure 4 It is the high-resolution transmission electron microscopy (HRTEM) image of the catalysts in Examples 1 to 4 of the present invention. Detailed Embodiments

[0027] The present invention will be described in detail below in conjunction with specific embodiments.

[0028] Example 1

[0029] Weigh out 0.68 g of solid powder of Ni(NO3)2·6H2O and 6.56 g of solid powder of Ce(NO3)3·6H2O in sequence and place them in beaker A. Add 25 mL of deionized water to dissolve, and stir to form a metal salt mixed solution. Weigh out 5.00 g of citric acid and dissolve it in 25 mL of deionized water. After stirring evenly, pour it into the above metal salt mixed solution, stir at room temperature for 1 h, and then place the mixed solution in a water bath at 80 °C and heat until the mixture forms a sol. Place the obtained sol in an oven at 85 °C and heat for 12 h to form a gel. After grinding the above gel into powder, carry out calcination in a muffle furnace, and heat it to 300 °C at a heating rate of 1 °C / min for 2 h, and then heat it to 450 °C at a heating rate of 2 °C / min -1 for 2 h to obtain a 5% Ni / CeO2 catalyst. -1

[0030] Example 2

[0031] Weigh out 1.43 g of solid powder of Ni(NO3)2·6H2O and 6.56 g of solid powder of Ce(NO3)3·6H2O in sequence and place them in beaker A. Add 25 mL of deionized water to dissolve, and stir to form a metal salt mixed solution. Weigh out 5.00 g of citric acid and dissolve it in 25 mL of deionized water. After stirring evenly, pour it into the above metal salt mixed solution, stir at room temperature for 1 h, and then place the mixed solution in a water bath at 80 °C and heat until the mixture forms a sol. Place the obtained sol in an oven at 85 °C and heat for 12 h to form a gel. After grinding the above gel into powder, carry out calcination in a muffle furnace, and heat it to 300 °C at a heating rate of 1 °C / min for 2 h, and then heat it to 450 °C at a heating rate of 2 °C / min -1 for 2 h to obtain a 10% Ni / CeO2 catalyst. -1

[0032] Example 3

[0033] Weigh out 2.27 g of solid powder of Ni(NO3)2·6H2O and 6.56 g of solid powder of Ce(NO3)3·6H2O in sequence and place them in beaker A. Add 25 mL of deionized water to dissolve, and stir to form a metal salt mixed solution. Weigh out 5.00 g of citric acid and dissolve it in 25 mL of deionized water. After stirring evenly, pour it into the above metal salt mixed solution, stir at room temperature for 1 h, and then place the mixed solution in a water bath at 80 °C and heat until the mixture forms a sol. Place the obtained sol in an oven at 85 °C and heat for 12 h to form a gel. After grinding the above gel into powder, carry out calcination in a muffle furnace, and heat it to 300 °C at a heating rate of 1 °C / min for 2 h, and then heat it to 450 °C at a heating rate of 2 °C / min -1 for 2 h​​-1 The temperature was raised to 450 °C at a heating rate of and heated for 2 h to obtain a 15% Ni / CeO2 catalyst.

[0034] Example 4

[0035] Weigh out 3.22 g of solid powder of Ni(NO3)2·6H2O and 6.56 g of solid powder of Ce(NO3)3·6H2O and place them in beaker A. Add 25 mL of deionized water to dissolve, and stir to form a metal salt mixed solution. Weigh out 5.00 g of citric acid and dissolve it in 25 mL of deionized water. After stirring evenly, pour it into the above metal salt mixed solution, stir at room temperature for 1 h, and then place the mixed solution in a water bath at 80 °C and heat until the mixture forms a sol. Place the obtained sol in an oven at 85 °C and heat for 12 h to form a gel. After grinding the above gel into powder, calcine it in a muffle furnace at a heating rate of 1 °C / min -1 to raise the temperature to 300 °C and heat for 2 h, and then at a heating rate of 2 °C / min -1 to raise the temperature to 450 °C and heat for 2 h to obtain a 20% Ni / CeO2 catalyst.

[0036] Example 5

[0037] Weigh out 0.68 g of solid powder of Ni(NO3)2·6H2O and 6.56 g of solid powder of Ce(NO3)3·6H2O and place them in beaker A. Add 25 mL of deionized water to dissolve, and stir to form a metal salt mixed solution. Weigh out 2.90 g of citric acid and dissolve it in 25 mL of deionized water. After stirring evenly, pour it into the above metal salt mixed solution, stir at room temperature for 1 h, and then place the mixed solution in a water bath at 80 °C and heat until the mixture forms a sol. Place the obtained sol in an oven at 85 °C and heat for 12 h to form a gel. After grinding the above gel into powder, calcine it in a muffle furnace at a heating rate of 1 °C / min -1 to raise the temperature to 300 °C and heat for 2 h, and then at a heating rate of 2 °C / min -1 to raise the temperature to 450 °C and heat for 2 h to obtain a 5% Ni / CeO2-CA 1:1 catalyst.

[0038] Example 6

[0039] Weigh out 0.68 g of Ni(NO3)2·6H2O and 6.56 g of Ce(NO3)3·6H2O solid powders in sequence and place them in beaker A. Add 25 mL of deionized water to dissolve, and stir to form a metal salt mixed solution. Weigh out 8.70 g of citric acid and dissolve it in 25 mL of deionized water. After stirring evenly, pour it into the above metal salt mixed solution, stir at room temperature for 1 h, and then place the mixed solution in a water bath at 80 °C and heat until the mixture forms a sol. Place the obtained sol in an oven at 85 °C and heat for 12 h to form a gel. Grind the above gel into powder and then calcine it in a muffle furnace, heating to 300 °C at a heating rate of 1 °C / min -1 and heating for 2 h, then heating to 450 °C at a heating rate of 2 °C / min -1 to obtain a 5% Ni / CeO2-CA 1:3 catalyst.

[0040] Example 7

[0041] Weigh out 0.68 g of Ni(NO3)2·6H2O and 6.56 g of Ce(NO3)3·6H2O solid powders in sequence and place them in beaker A. Add 25 mL of deionized water to dissolve, and stir to form a metal salt mixed solution. Weigh out 1.13 g of glycine and dissolve it in 25 mL of deionized water. After stirring evenly, pour it into the above metal salt mixed solution, stir at room temperature for 1 h, and then place the mixed solution in a water bath at 80 °C and heat until the mixture forms a sol. Place the obtained sol in an oven at 85 °C and heat for 12 h to form a gel. Grind the above gel into powder and then calcine it in a muffle furnace, heating to 300 °C at a heating rate of 1 °C / min -1 and heating for 2 h, then heating to 450 °C at a heating rate of 2 °C / min -1 to obtain a 5% Ni / CeO2-Gly catalyst.

[0042] Comparative Example 1

[0043] Weigh out 0.99 g of Fe(NO3)3·9H2O and 6.56 g of Ce(NO3)3·6H2O solid powders in sequence and place them in beaker A. Add 25 mL of deionized water to dissolve, and stir to form a metal salt mixed solution. Weigh out 5.00 g of citric acid and dissolve it in 25 mL of deionized water. After stirring evenly, pour it into the above metal salt mixed solution, stir at room temperature for 1 h, and then place the mixed solution in a water bath at 80 °C and heat until the mixture forms a sol. Place the obtained sol in an oven at 85 °C and heat for 12 h to form a gel. Grind the above gel into powder and then calcine it in a muffle furnace, heating to 300 °C at a heating rate of 1 °C / min -1 and heating for 2 h, then heating to 450 °C at a heating rate of 2 °C / min -1The 5% Fe / CeO2 catalyst was obtained by heating to 450 °C at a heating rate and heating for 2 h.

[0044] Comparative Example 2

[0045] Weigh 0.68 g of solid powder of Co(NO3)2·6H2O and 6.56 g of Ce(NO3)3·6H2O and place them in beaker A. Add 25 mL of deionized water to dissolve, and stir to form a metal salt mixed solution. Weigh 5.00 g of citric acid and dissolve it in 25 mL of deionized water. After stirring evenly, pour it into the above metal salt mixed solution and stir at room temperature for 1 h. Then place the mixed solution in a water bath at 80 °C and heat until the mixture forms a sol. Place the obtained sol in an oven at 85 °C and heat for 12 h to form a gel. After grinding the above gel into powder, calcine it in a muffle furnace at a heating rate of 1 °C / min -1 and heat to 300 °C for 2 h, and then at a heating rate of 2 °C / min -1 heat to 450 °C for 2 h to obtain the 5% Co / CeO2 catalyst.

[0046] Performance evaluation of carbon dioxide hydrogenation reaction

[0047] The catalysts prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were respectively subjected to performance evaluation of carbon dioxide hydrogenation reaction. Weigh 0.1 g of the catalyst and load it into the quartz reaction tube of a fixed-bed reactor. First, perform H2 reduction treatment on the above catalyst, in-situ reduction at 500 °C for 2 h. After the reduction is completed, cool to below the reaction temperature and introduce the raw material gas for reaction. Carbon dioxide hydrogenation reaction conditions: atmospheric pressure, reaction temperature 200 - 400 °C, molar ratio of H2 to CO2 in the raw material gas is 4, and the volumetric space velocity of the raw material gas is 60000 mL h -1 g cat -1 . The raw material gas and reaction products were analyzed online by an Agilent 8860 gas chromatograph equipped with a TDX-01 packed column and a TCD detector.

[0048] It can be seen from Figure 1 that with the increase of the metal loading, the activity of the catalyst gradually increases. When the metal loading is 15 wt% (Example 3), the catalyst has excellent low-temperature catalytic activity. At a reaction temperature of 260 °C, the carbon dioxide conversion rate of the catalyst reaches 80%, and the selectivity of CH4 is 99.5%.

[0049] It can be seen from Figure 2 that the activity and selectivity of methane products of the Ni-based catalyst (Example 1) are much higher than those of the Fe-based (Comparative Example 1) and Co-based catalysts (Comparative Example 2). The highly dispersed Ni-based catalyst provided by the present invention has excellent carbon dioxide hydrogenation methanation performance.

[0050] From Figure 3 It can be seen from the XRD results that no obvious characteristic diffraction peaks of metallic nickel appeared in the XRD patterns of the catalysts of Examples 1 to 4, indicating that the Ni metal particles had a small particle size, the metal was highly dispersed, and the metal utilization rate was high.

[0051] From Figure 4 It can be seen from the HRTEM results that the Ni particles were highly dispersed in the lattice of the carrier cerium dioxide, which was also the reason for the small particle size and high temperature stability of the Ni metal. The catalyst provided by the present invention had a high metal utilization rate and was highly stable, and was suitable for large-scale industrial production and use.

[0052] In summary, the present invention adopted a sol-gel technology to prepare a highly dispersed nickel-based catalyst. The preparation method of the catalyst in the present invention was simple to operate, had good repeatability, and was beneficial to large-scale industrial use. In the present invention, Ni was highly dispersed in the lattice of CeO2, the Ni particle size was small, which significantly improved the metal utilization efficiency, and the Ni particles could remain stable at high temperatures. The highly dispersed nickel-based catalyst provided in the present invention was used for the carbon dioxide hydrogenation methanation reaction, had high reaction activity, high product selectivity, and the catalyst had good stability. The present invention provided an effective implementation scheme for the resource utilization of CO2.

[0053] Those of ordinary skill in the art can understand that the above embodiments are specific examples for implementing the present invention, and in practical applications, various changes can be made in form and details without departing from the spirit and scope of the present invention. Any person skilled in the art can make respective changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A method for preparing a highly dispersed nickel-based catalyst, characterized in that: The preparation method comprises: Dissolve the nickel salt precursor and the cerium salt precursor in deionized water, add a complexing agent, and stir for 0.5 to 4 hours until the mixture is uniformly mixed to obtain a mixed solution; The mixed solution is heated in a water bath at a temperature of 50 to 85° C. to obtain a sol; the sol is placed in a temperature environment of 60 to 150° C. and dried for 6 to 24 hours to obtain a gel; The gel is ground to obtain powder; first, at 1-5°C min -1 The heating rate is raised to 200-300℃ and calcined for 2-8h, and then calcined at 1-10℃min -1 The powder is calcined in stages according to the operating parameters of heating rate to 400-600° C. and continuing calcination for 2-8 hours to obtain the highly dispersed nickel-based catalyst, which is recorded as Ni / CeO2 catalyst.

2. The method for preparing a highly dispersed nickel-based catalyst according to claim 1, characterized in that: The nickel salt precursor includes one or more of Ni(NO3)2·6H2O, NiCl2·6H2O, NiSO4·6H2O, and Ni(Ac)2·4H2O; The cerium salt precursor includes one or more of Ce(NO3)3·6H2O, CeCl3·7H2O, and Ce(Ac)3·xH2O; The complexing agent includes one or more of citric acid, ethylenediaminetetraacetic acid, glycine, and polyacrylic acid.

3. The method for preparing a highly dispersed nickel-based catalyst according to claim 1, characterized in that: The molar ratio of the cerium source cerium salt precursor to the complexing agent is 1:1 to 3:

1.

4. The method for preparing a highly dispersed nickel-based catalyst according to claim 1, characterized in that: The water bath temperature is 60-80° C.; the drying temperature is 80-120° C., and the drying time is 8-12 hours.

5. The method for preparing a highly dispersed nickel-based catalyst according to claim 1, characterized in that: The operating parameters of the staged roasting specifically include: first, at 1-3 °C min -1 The heating rate is raised to 200-300℃ and calcined for 4-6h, and then calcined at 2-5℃min -1 Raise the temperature to 400-600°C and continue calcining for 4-6 hours.

6. The highly dispersed nickel-based catalyst obtained by the method for preparing a highly dispersed nickel-based catalyst according to any one of claims 1 to 5.

7. The highly dispersed nickel-based catalyst according to claim 6, characterized in that: The catalyst comprises active metal Ni and CeO2 as a carrier; wherein the content of the active metal Ni is 1wt% to 50wt%, and the content of CeO2 is 50wt% to 99wt%; Preferably, the content of the active metal Ni is 5wt% to 20wt%.

8. Use of the highly dispersed nickel-based catalyst as claimed in claim 6 in the reaction of hydrogenating carbon dioxide to produce methane.

9. The use according to claim 8, characterized in that: The application method in the carbon dioxide hydrogenation to methane reaction includes: performing in-situ reduction pretreatment on the highly dispersed nickel-based catalyst before the reaction; in the in-situ reduction pretreatment, the reduction temperature is 300-600°C, preferably 400-500°C; the reducing atmosphere is high-purity H2 or H2 and one or more inert gases such as N2, Ar, He, etc.

10. The use according to claim 9, characterized in that: After the in-situ reduction pretreatment, the method further includes conducting a catalyst reaction evaluation on the highly dispersed nickel-based catalyst; in the catalyst reaction evaluation, a normal pressure quartz tube fixed bed reactor is used, the reaction temperature is 200-400° C.; the molar ratio of H2 to CO2 in the raw gas is 0.5-6, preferably 2-4; the gas volume space velocity is 6000-120000 mL h -1 g cat -1 , preferably 12000~90000mL h -1 g cat -1 .

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