Preparation method and application of a catalyst for the methanation of coke oven gas

Abstract

The present invention provides a novel catalyst for the methanation of coke oven gas, which overcomes the defect of low CO2 conversion rate in the presence of coexisting CO and CO2 during the methanation of coke oven gas. The prepared catalyst uses hydrotalcite as a precursor and has a typical layered double metal hydroxide (LDHs) structure. The preparation process is simple. In the case of a high loading amount of active components, it has good sulfur resistance, excellent CO and CO2 conversion rates, and good CH4 selectivity at the same time.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a catalyst suitable for the methanation reaction of coke oven gas. Background Art

[0002] The characteristics of China's basic energy pattern are rich in coal, scarce in oil and gas. As a kind of environmental-friendly and clean energy, natural gas has received more and more extensive attention in recent years with the increasing demand for it. China is a major coke-producing country. As of the end of 2022, China's coke output was 473 million tons. Among them, coke oven gas is a mixed gas produced after coal dry distillation in the coke production process. Coke oven gas is mainly used for ammonia production, methanol production, etc. Among them, about 15% of coke oven gas is directly discharged into the air or burned, which not only causes huge waste but also pollutes the environment. Methanation of coke oven gas can effectively solve the comprehensive utilization problem of coke oven gas and relieve the shortage of domestic natural gas.

[0003] The typical composition of coke oven gas is shown in Table 1 below:

[0004] Table 1 Typical Composition of Coke Oven Gas

[0005] Composition <![CDATA[H 2 > <![CDATA[CH 4 > CO <![CDATA[CO 2 > <![CDATA[N 2 > <![CDATA[O 2 > <![CDATA[C m H n > Content (volume fraction) / % 54～59 24～28 5.5～7 1～3 3～5 0.3～0.7 2～3

[0006] The technical principle of coke oven gas methanation is shown in Reaction Formula 1 and Reaction Formula 2:

[0007] CO + 3H 2 →CH 4 + H 2 O (Reaction Formula 1)

[0008] CO 2 + 4H 2 →CH 4 + H 2 O (Reaction Formula 2)

[0009] The above reactions are all exothermic reactions. Among them, for every 1% conversion of CO and CO 2 the adiabatic temperature rises are 72°C and 60°C respectively. Due to the large temperature rise in the coke oven gas methanation reaction and the rapid instantaneous heat release, this may lead to problems such as catalyst carbon deposition or high-temperature deactivation. Therefore, it is very necessary to develop a methanation catalyst with high activity, good high-temperature stability, excellent anti-carbon deposition and anti-sulfur performance.

[0010] CO and CO 2 Methanation catalysts are typical supported catalysts. The studied catalyst active components include Ni, Fe, Co, Ru, Rh, Pt, Pd, W, Mo, etc. The carrier is generally Al 2 O 3 , SiO2 , TiO 2 , ZrO2, CeO 2 , and their composite oxides, etc. Currently, nickel-based catalysts are mainly used as methanation catalysts in industry. Nickel-based catalysts have high catalytic activity and low cost, but such catalysts will sinter and agglomerate at high temperatures, resulting in carbon deposition, which makes the catalysts easily deactivate. At the same time, the coke oven gas also contains sulfur-containing impurities such as naphthalene, hydrogen sulfide, COS, carbon disulfide, ammonia, and thiophene. Since there are available d orbitals in the valence electron layer structure of nickel element, this d orbital is easy to combine with sulfur with lone pair electrons in sulfur-containing compounds to form strong coordination bonds, so that sulfur can be stably adsorbed on the nickel surface, destroying the active sites of the catalyst and reducing the catalytic activity of the catalyst. This sulfur poisoning is one of the important factors for the deactivation of methanation catalysts, and the degree of damage caused by sulfur poisoning to the catalyst is much greater than that of carbon deposition and sintering. Therefore, most of the existing methanation processes require desulfurization treatment of the mixed gas before the methanation process. To solve this problem, it is of great significance to develop a catalyst that still has good methane catalytic activity in a certain sulfur-containing atmosphere. By using a sulfur-resistant methanation catalyst, the raw material gas can only undergo rough desulfurization or no desulfurization, which greatly simplifies the process flow, reduces energy consumption, and saves costs.

[0011] Hydrotalcite is a metal oxide with a two-dimensional layered structure, and its general formula is: [M 2+ 1-x M 3+ x (OH) 2 x+ (An-) x / n ·mH 2 O, where M 2+ and M 3+ represent divalent and trivalent metal cations on the cation layer respectively, An- represents the interlayer anion, x is the molar ratio of M 3+ / (M 2+ +M 3+ ), and m is the number of interlayer water molecules. The advantages of hydrotalcite such as adjustable basicity, particle size, and simple preparation process have made it widely used in the catalytic field. The adjustable variability of the interlayer anions of hydrotalcite makes it have better dispersibility, and it is an excellent precursor for preparing highly dispersed catalysts, which can effectively prevent the sintering and agglomeration of the active components of methanation catalysts. The metal oxide (LDO) obtained by calcining the methanation catalyst prepared from the hydrotalcite precursor has the characteristics of high active component loading and high dispersion. After calcination, its layered structure collapses, thereby increasing the specific surface area of the catalyst, and also greatly improving the basicity of the catalyst, which helps to improve the adsorption and activation of reactant molecules.

[0012] ​There are many studies on the preparation of methanation catalysts using hydrotalcite as a precursor in China. For example, patent CN107376925A provides a low-temperature and highly active carbon dioxide methanation catalyst with a nickel-aluminum hydrotalcite structure. Using nickel-aluminum hydrotalcite as a precursor, nickel-aluminum composite oxide is obtained after calcination, which improves the dispersion of nickel components. The interaction between nickel and aluminum also effectively prevents the sintering and hydrothermal oxidation of nickel. At the same time, by adding modifiers such as Fe, Mg, Ce, and La, the adsorption capacity for H 2 and CO 2 is appropriately regulated, improving the selectivity of methane. However, after the activity evaluation of the catalyst, it is found that when the temperature of the catalyst exceeds 400 °C, carbon deposition is likely to occur, and the catalytic activity decreases significantly. The CO 2 conversion rate drops from 99% to 95%, indicating that the catalyst still has deficiencies in heat resistance. CN111495378A discloses a methanation catalyst obtained by using metal oxide-supported Ni(NO 3 ) 2 as a precursor, calcining in an ammonia atmosphere and then reducing with hydrogen. Since more active oxygen vacancies are generated after calcination in an ammonia atmosphere, its anti-carbon deposition performance and catalytic activity are improved, thereby extending the service life of the catalyst. Its hydrotalcite-derived intercalated structure and high dispersion contribute to improving the stability of the catalyst. After testing the performance of the prepared catalyst, the catalyst has good catalytic activity for CO, but the conversion rate of CO 2 is lower than 90%.

[0013] In the coke oven gas methanation process, the coal-derived substitute natural gas (SNG) after catalytic reduction, due to the requirements of the cryogenic liquefaction process, the content of CO 2 in the outlet gas of the methanation process must be lower than 50 ppm. The presence of CO 2 will increase the freezing point and gasification temperature of SNG, making the requirements for pressure and temperature higher during the liquefaction process. At the same time, CO 2 will react with CH 4 to form other compounds, reducing the calorific value and quality of SNG. Currently, both domestic and foreign in the development of methanation catalysts have good effects in the catalytic conversion of CO, but in the coexistence of CO and CO 2 , due to the influence of CO inhibiting the adsorption of CO 2 , the conversion rate of CO 2 is relatively low. Therefore, a new type of coke oven gas methanation catalyst is studied to solve this problem. Summary of the Invention

[0014] The purpose of the present invention is to provide a new catalyst for coke oven gas methanation, which overcomes the problem that the conversion rate of CO 2 is low in the coexistence of CO and CO 2Defects of low conversion rate. The prepared catalyst uses hydrotalcite as a precursor, has a typical layered double metal hydroxide (LDHs) structure, has a simple preparation process, has good sulfur resistance under the condition of a high active component loading amount, and also has excellent CO and CO 2 conversion rate, as well as good CH 4 selectivity.

[0015] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0016] The present invention provides a catalyst for the methanation of coke oven gas, and the methanation catalyst is directly calcined from a nickel-based quaternary hydrotalcite precursor modified by a modifier.

[0017] The catalyst is obtained by calcining a hydrotalcite as a precursor at a certain temperature. The obtained precursor has a typical LDHs structure. During the preparation process, the addition of Fe helps to improve the CO 2 methanation activity of the nickel-based catalyst. After calcination, a nickel-based quaternary metal oxide (NiZrFeAl-LDO) is formed, which has a larger specific surface area than the precursor. The basic centers in its structure are fully exposed, and it has stronger basicity than the precursor. Therefore, the catalyst can adsorb and activate CO and CO 2 more quickly, enhancing the catalytic activity of the catalyst for the two.

[0018] Due to its large specific surface area, the metal Ni in the catalyst can be widely and evenly distributed on the surface of the carrier, enabling the synthesis of a high-loading Ni catalyst, improving the dispersion degree of Ni, and ZrO 2 and TiO 2 can both improve the dispersion degree of Ni and also promote the hydrogenation of CO. After high-temperature calcination and reduction, the grain size of Ni is reduced, making the catalyst have more excellent anti-sintering and agglomeration resistance and stability. And the addition of alkaline earth metals also provides more active centers for the catalyst, improving the catalytic activity of the catalyst.

[0019] The catalyst adds Mo as a modifier. The addition of Mo can effectively improve the sulfur resistance of the catalyst. This is because the Mo catalyst is insensitive to sulfur-containing compounds, and the interaction between Ni-Mo makes the interaction between the active components and the carrier in the catalyst moderate, which is beneficial to the adsorption and desorption of hydrogen, weakens the adsorption of sulfides, enhances the sulfur resistance of the catalyst, and effectively extends the service life of the catalyst.

[0020] The rare earth elements La and Ce used in the modifier significantly improve the sulfur resistance of the catalyst. Adding CeO 2 or La 2 O 3Not only improves the catalytic activity of the catalyst, but also the formed La after reduction 2 O 3 surrounds the Ni nanoparticles, thereby improving the anti-sintering ability of the catalyst.

[0021] For the catalyst provided by the present invention, based on 100% of the mass of the catalyst,

[0022] the mass content of the Ni component is 20-70%;

[0023] the mass content of the Zr component is 10-40%;

[0024] the mass content of the Fe component is 5-40%; the mass content of the Al component is 5-40%;

[0025] the total mass content of the modifiers is 0-15%, and the mass ratio of Mo:La:Ce is (2-4):(4-5):(2-3).

[0026] Preferably, the composition of the catalyst is, based on 100% of the mass of the catalyst, the mass content of the Ni component is 50-55%, the mass content of the Zr component is 18-20%, the mass content of the Fe component is 10-12%, the mass content of the Al component is 4-6%, the mass content of the Mo component is 2-4%, the mass content of the La component is 3-5%, and the mass content of the Ce component is 2-4%.

[0027] More preferably, the composition of the catalyst is, based on 100% of the mass of the catalyst, the mass content of the Ni component is 52.7%, the mass content of the Zr component is 19.5%, the mass content of the Fe component is 11.99%, the mass content of the Al component is 5.78%, the mass content of the Mo component is 3.14%, the mass content of the La component is 4.55%, and the mass content of the Ce component is 2.31%.

[0028] The preparation method of the coke oven gas methanation catalyst of the present invention, the preparation method includes the following steps:

[0029] (1), Weigh a certain amount of soluble salts of Ni, Al, Zr, and Fe respectively, and dissolve them in deionized water to form a solution. Mix the prepared solutions in proportion and stir evenly to obtain a metal salt solution, denoted as solution A. Among them, the ratio is the molar ratio of Ni 2+ :Zr 2+ :Fe 3+ :Al 3+ in solution A is (2-5):1:1:1.

[0030] (2) Prepare a certain amount of alkali solution as the precipitant, denoted as Solution B.

[0031] (3) Measure a certain amount of deionized water, slowly drop Solution A and Solution B into the deionized water, and stir vigorously at the same time. During the whole feeding process, control the pH value at 9.0 - 10.0. After the feeding is completed, continue to stir the obtained precipitate at 60 °C for a certain time and then stand for aging treatment. After filtration, washing, and drying, a catalyst precursor (nickel-based quaternary hydrotalcite, i.e., NiZrFeAl-LDH) is obtained; the catalyst precursor is calcined under certain temperature conditions to obtain a metal composite oxide (NiZrFeAl-LDO).

[0032] (4) Weigh a certain amount of soluble salts of Ni, Mo, Ce, and La respectively, and dissolve them in deionized water to prepare a solution. Mix the prepared solutions evenly, heat and stir to obtain a metal salt solution, denoted as Solution C. Among them, the ratio is in terms of molar ratio of Ni 2+ : Mo 4+ : La 3+ : Ce 4+ with a molar content ratio of (8 - 35):(2 - 3):(1 - 2):1, or the ratio is in terms of mass ratio of (5 - 20):(2 - 4):(4 - 5):(2 - 3).

[0033] (5) Mix the metal composite oxide obtained in step (3), Solution C, and Solution B, stir vigorously, control the pH value at 9.0 - 10.0. After mixing, continue to stir the obtained precipitate at 60 °C for a certain time and then stand for aging treatment. After filtration, washing, and drying, a modified catalyst precursor is obtained; the modified catalyst precursor is calcined under certain temperature conditions to obtain a modified Ni / Zr / Fe / Al hydrotalcite catalyst.

[0034] In the above preparation method, in step (3), the catalyst precursor (nickel-based quaternary hydrotalcite, i.e., NiZrFeAl-LDH) is calcined to form a metal composite oxide (NiZrFeAl-LDO) with a larger specific surface area than hydrotalcite, so that the basic centers in its structure are fully exposed. The obtained catalyst has Ni particles and is uniformly dispersed in the catalyst and contains more active oxygen vacancies, has stronger basicity than hydrotalcite, enhancing the catalytic activity and anti-coking performance of the catalyst. In step (5), the added modifier Mo reduces the sensitivity of the catalyst to sulfur-containing substances and effectively improves the sulfur resistance of the catalyst.

[0035] Furthermore, in step (1), the soluble salt of Ni is any one or a mixture of at least two of nickel nitrate, nickel sulfate, nickel chloride, nickel acetate, etc.

[0036] Further, in the step (1), the soluble salt of Al is any one or a mixture of at least two of aluminum nitrate, aluminum sulfate, aluminum chloride, aluminum acetate, etc.

[0037] Further, in the step (1), the soluble salt of Fe is any one or a mixture of at least two of iron nitrate, iron chloride, iron sulfate, etc.

[0038] Further, in the step (1), the soluble salt of Zr is any one or a mixture of two of zirconium nitrate, zirconium sulfate, etc.

[0039] Further, in the step (1), the total mass content of each metal component in the mixed solution A is 15 - 50 g / L.

[0040] Further, in the step (2), the precipitant (alkali solution) is any one or a mixture of at least two of sodium carbonate, sodium hydroxide, sodium bicarbonate, ammonia water, potassium hydroxide, potassium carbonate, potassium bicarbonate, etc.

[0041] Further, in the step (2), the concentration of the precipitant in the solution B is 1 - 10 mol / L.

[0042] Further, in the step (3), the stirring reaction time is 2 - 6 h.

[0043] Further, in the step (3), the time for static aging treatment is 6 - 24 h, such as 8 h, 10 h, 12 h, 14 h, 16 h, 20 h, 24 h, etc.

[0044] Further, in the step (3), the drying temperature is 60 - 120 °C.

[0045] Further, in the step (3), the drying time is 12 - 24 h.

[0046] Further, in the step (3), the calcination temperature is 400 - 600 °C.

[0047] Further, in the step (3), the calcination time is 3 - 6 h.

[0048] Further, in the step (4), the modifier includes any one or a combination of multiple soluble salts of Mo, Ce, and La.

[0049] Further, in the step (4), the total mass content of each metal component in the solution C is 5 - 15 g / L.

[0050] Further, in the step (5), the stirring reaction time is 3 - 6 h.

[0051] Further, in the step (5), the time for static aging treatment is 6 - 24 h.

[0052] Further, in the step (5), the drying temperature is 60 to 120 °C.

[0053] Further, in the step (5), the drying time is 12 to 24 h.

[0054] Further, in the step (5), the calcination temperature is 400 to 600 °C.

[0055] Further, in the step (5), the calcination time is 3 to 6 h.

[0056] Beneficial effects

[0057] (1) The catalyst provided by the present invention is obtained by calcining a hydrotalcite as a precursor at a certain temperature. After calcination, the formed nickel-based quaternary metal oxide (NiZrFeAl-LDO) has a larger specific surface area, and the basic centers in its structure are fully exposed, having stronger basicity, so that the catalyst can adsorb and activate CO and CO more quickly 2 and enhance the catalytic activity of the catalyst for the two.

[0058] (2) By modifying the catalyst with Mo, La or Ce, the catalyst is insensitive to sulfur-containing compounds and has excellent sulfur resistance. At the same time, the addition of modifiers such as Mo, La, Ce, etc. makes the Ni particles in the obtained catalyst uniformly dispersed in the catalyst and contain more active oxygen vacancies, which is beneficial to improving the catalytic activity and anti-coking performance of the catalyst.

[0059] (3) The preparation process and equipment of the catalyst described in the present invention are simple, the production cost is low, it is suitable for mass production, and it is beneficial to industrial application. Description of the drawings

[0060] Figure 1 XRD pattern of the Ni-based quaternary hydrotalcite and its oxide prepared in Example 1

[0061] Figure 2 Infrared spectrum of the Ni-based quaternary hydrotalcite and its oxide prepared in Example 1

[0062] Figure 3 Adsorption-desorption curve of the Ni-based quaternary hydrotalcite and its oxide prepared in Example 1 Detailed implementation manners

[0063] The present invention will be described in more detail below through specific examples, and these examples do not limit the protection scope of the present invention. In the following examples, when the percentage content is involved, it is the mass percentage.

[0064] I. Catalyst preparation examples

[0065] Preparation Example 1

[0066] This example provides a Ni-based modified catalyst, which is prepared by the following method:

[0067] In the quaternary hydrotalcite precursor (i.e., Ni-based quaternary hydrotalcite (NiZrFeAl-LDH)), the molar ratio of Ni 2+ :Zr 2+ :Fe 3+ :Al 3+ is 3:1:1:1, and the mass of Mo, La, and Ce modifiers accounts for 5% of the catalyst mass. The molar ratio of Mo, La, and Ce in the modifier is 2:2:1.

[0068] (1) Weigh zirconium sulfate hexahydrate, ferric nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate according to the molar ratio of Ni 2+ :Zr 2+ :Fe 3+ :Al 3+ of 3:1:1:1, add 300 mL of deionized water, and prepare solution A with a concentration of 30 g / L of the sum of the masses of each component;

[0069] (2) Weigh sodium hydroxide, dissolve it in deionized water, and prepare solution B with a concentration of 1 mol / L;

[0070] (3) Slowly drip solution A and solution B into a four-necked flask and stir. During the feeding process, control the pH value of the mixed solution at 9.0 - 10. After completion, continue to stir and react at 60 °C for 6 h, then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h to obtain Ni-based quaternary hydrotalcite (NiZrFeAl-LDH), and then place it in a muffle furnace and calcine at 450 °C for 5 h to obtain a metal composite oxide;

[0071] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni, Mo, La, and Ce of 18:3.2:4.3:2.3, add 300 mL of deionized water, and prepare solution C with a concentration of 5 g / L of the sum of the masses of each component;

[0072] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly drip the mixed solution B and solution C, and stir. During the feeding process, control the pH value of the mixed solution at 9.0 - 10. After completion, continue to stir and react at 60 °C for 6 h, then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h, and place it in a muffle furnace and calcine at 450 °C for 5 h to obtain Catalyst 1.

[0073] Preparation Example 2

[0074] In the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)), Ni 2+ :Zr 2+ :Fe 3+ :Al 3+ with a molar ratio of 3:1:1:1, and the mass of Mo, La, and Ce modifiers accounts for 10% of the catalyst mass, and the molar ratio of Mo, La, and Ce in the modifier is 3:1:1.

[0075] (1) Weigh zirconium sulfate hexahydrate, ferric nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare solution A with a concentration of 30 g / L of the sum of the masses of each component;

[0076] (2) Weigh sodium hydroxide, dissolve it in deionized water to obtain solution B with a concentration of 1 mol / L;

[0077] (3) Slowly drip solution A and solution B into a four-necked flask and stir. During the feeding process, control the pH value of the mixed solution at 9.0 - 10. After completion, continue to stir and react at 60 °C for 6 h, then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH), and then place it in a muffle furnace and calcine at 450 °C for 5 h to obtain a metal composite oxide;

[0078] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni, Mo, La, and Ce of 4.3:5:2.5:2.5, add 300 mL of deionized water, and prepare solution C with the sum of the masses of each component being 5 g / L;

[0079] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly drip the mixed solution B and solution C, and stir. During the feeding process, control the pH value of the mixed solution at 9.0 - 10. After completion, continue to stir and react at 60 °C for 6 h, then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h, and place it in a muffle furnace and calcine at 450 °C for 5 h to obtain catalyst 2.

[0080] Preparation Example 3

[0081] In the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)), Ni 2+ :Zr 2+ :Fe 3+ :Al 3+ with a molar ratio of 3:1:1:1, and the mass of Mo, La, and Ce modifiers accounts for 15% of the catalyst mass, and the molar ratio of Mo, La, and Ce in the modifier is 2:2:1.

[0082] (1) Weigh zirconium sulfate hexahydrate, ferric nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate proportionally, add 300 mL of deionized water, and prepare solution A with a concentration of 30 g / L based on the sum of the masses of each component.

[0083] (2) Weigh sodium hydroxide and dissolve it in deionized water to obtain solution B with a concentration of 1 mol / L.

[0084] (3) Slowly drip solution A and solution B into a four-necked flask and stir. During the feeding process, control the pH value of the mixed solution at 9.0 - 10. After completion, continue to stir and react at 60 °C for 6 h, then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH), and then calcine it in a muffle furnace at 450 °C for 5 h to obtain a metal composite oxide.

[0085] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni:Mo:La:Ce of 6.7:3.2:4.5:2.3, add 300 mL of deionized water, and prepare solution C with a sum of the masses of each component of 10 g / L.

[0086] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly drip the mixed solution B and solution C, and stir. During the feeding process, control the pH value of the mixed solution at 9.0 - 10. After completion, continue to stir and react at 60 °C for 6 h, then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h, and calcine it in a muffle furnace at 450 °C for 5 h to obtain catalyst 3.

[0087] Preparation Example 4

[0088] In the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)), the molar ratio of Ni 2+ :Zr 2+ :Fe 3+ :Al 3+ is 3:1:1:1, and the mass of the Mo, La, Ce modifiers accounts for 10% of the mass of the catalyst, and the molar ratio of Mo, La, Ce in the modifier is 2:2:1.

[0089] (1) Weigh zirconium sulfate hexahydrate, ferric nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate proportionally, add 300 mL of deionized water, and prepare solution A with a concentration of 30 g / L based on the sum of the masses of each component.

[0090] (2) Weigh sodium hydroxide and dissolve it in deionized water to obtain solution B with a concentration of 1 mol / L.

[0091] (3) Slowly drop solution A and solution B into the four-necked flask and stir. During the feeding process, control the pH value of the mixed solution at 9.0 - 10. After completion, continue to stir and react for 6 h at 60 °C, then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH), and then place it in a muffle furnace and calcine at 500 °C for 5 h to obtain the metal composite oxide;

[0092] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni:Mo:La:Ce of 15:3.2:4.5:2.3, add 300 mL of deionized water, and prepare solution C with the sum of the masses of each component being 10 g / L;

[0093] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly drop the mixed solution B and solution C, and stir. During the feeding process, control the pH value of the mixed solution at 9.0 - 10. After completion, continue to stir and react for 6 h at 60 °C, then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h, and place it in a muffle furnace and calcine at 500 °C for 5 h to obtain the methanation catalyst 4.

[0094] Preparation Example 5

[0095] In the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)), the molar ratio of Ni 2+ :Zr 2+ :Fe 3+ :Al 3+ is 3:1:1:1, and the mass of the Mo, La, Ce modifiers accounts for 10% of the catalyst mass. The molar ratio of Mo, La, Ce in the modifier is 2:2:1.

[0096] (1) Weigh zirconium sulfate hexahydrate, ferric nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare solution A with the concentration of the sum of the masses of each component being 30 g / L;

[0097] (2) Weigh sodium hydroxide and dissolve it in deionized water to obtain solution B with a concentration of 1 mol / L;

[0098] (3) Slowly drop solution A and solution B into the four-necked flask and stir. During the feeding process, control the pH value of the mixed solution at 9.0 - 10. After completion, continue to stir and react for 6 h at 60 °C, then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH), and then place it in a muffle furnace and calcine at 550 °C for 5 h to obtain the metal composite oxide;

[0099] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of 15:3.2:4.5:2.3, add 300 mL of deionized water, and prepare solution C with the sum of the masses of each component being 10 g / L;

[0100] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly dropwise add mixed solution B and solution C, and stir. During the feeding process, control the pH value of the mixed solution at 9.0 - 10. After completion, continue to stir and react at 60 °C for 6 h, then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h, and calcine in a muffle furnace at 550 °C for 5 h to obtain the methanation catalyst 5.

[0101] According to the preparation process of this example, it can be calculated that the composition of the prepared catalyst is as follows: based on 100% of the mass of the catalyst, the mass content of the Ni component is 52.7%, the mass content of the Zr component is 19.5%, the mass content of the Fe component is 11.99%, the mass content of the Al component is 5.78%, the mass content of the Mo component is 3.14%, the mass content of the La component is 4.55%, and the mass content of the Ce component is 2.31%.

[0102] Preparation Example 6

[0103] The molar ratio of Ni 2+ :Zr 2+ :Fe 3+ :Al 3+ in the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)) is 3:1:1:1, and the mass of the Mo, La, Ce modifiers accounts for 10% of the mass of the catalyst, and the molar ratio of Mo, La, Ce in the modifier is 2:2:1.

[0104] (1) Weigh zirconium sulfate hexahydrate, ferric nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare solution A with the concentration of the sum of the masses of each component being 30 g / L;

[0105] (2) Weigh sodium hydroxide, dissolve it in deionized water to obtain solution B with a concentration of 1 mol / L;

[0106] (3) Slowly drop solution A and solution B into a four-necked flask and stir. During the feeding process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue stirring and reacting at 60 °C for 6 h. Then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH), and then place it in a muffle furnace and calcine at 600 °C for 5 h to obtain a metal composite oxide;

[0107] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni:Mo:La:Ce of 15:3.2:4.5:2.3, add 300 mL of deionized water, and prepare solution C with the sum of the masses of each component being 10 g / L;

[0108] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly drop and stir the mixed solution B and solution C. During the feeding process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue stirring and reacting at 60 °C for 6 h. Then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h, and place it in a muffle furnace and calcine at 600 °C for 5 h to obtain the methanation catalyst 6.

[0109] Preparation Example 7

[0110] In the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)), the molar ratio of Ni 2+ :Zr 2+ :Fe 3+ :Al 3+ is 4:1:1:1, and the mass of the Mo, La, Ce modifiers accounts for 10% of the catalyst mass. The molar ratio of Mo, La, Ce in the modifier is 2:2:1.

[0111] (1) Weigh zirconium sulfate hexahydrate, ferric nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare solution A with the concentration of the sum of the masses of each component being 30 g / L;

[0112] (2) Weigh sodium hydroxide and dissolve it in deionized water to obtain solution B with a concentration of 1 mol / L;

[0113] (3) At 60 °C, slowly drop solution A and solution B into a four-necked flask and stir. During the feeding process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue stirring and reacting at 60 °C for 6 h. Then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH), and then place it in a muffle furnace and calcine at 550 °C for 5 h to obtain a metal composite oxide;

[0114] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of 15:3.2:4.5:2.3, add 300 mL of deionized water, and prepare solution C with the sum of the masses of each component being 10 g / L;

[0115] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly dropwise add mixed solution B and solution C, and stir. During the feeding process, control the pH value of the mixed solution at 9.0 - 10. After completion, continue to stir and react at 60 °C for 6 h, then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h, and calcine in a muffle furnace at 550 °C for 5 h to obtain the methanation catalyst 7.

[0116] Preparation Example 8

[0117] In the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)), the molar ratio of Ni 2+ :Zr 2+ :Fe 3+ :Al 3+ is 5:1:1:1, and the mass of the Mo, La, Ce modifiers accounts for 10% of the catalyst mass, and the molar ratio of Mo, La, Ce in the modifier is 2:2:1.

[0118] (1) Weigh zirconium sulfate hexahydrate, ferric nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare solution A with the sum of the masses of each component being 30 g / L;

[0119] (2) Weigh sodium hydroxide, dissolve it in deionized water to obtain solution B with a concentration of 1 mol / L;

[0120] (3) Slowly dropwise add solution A and solution B into a four-necked flask and stir. During the feeding process, control the pH value of the mixed solution at 9.0 - 10. After completion, continue to stir and react at 60 °C for 6 h, then let it stand for 24 h, filter and wash several times, dry at 105 °C for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH), and then calcine it in a muffle furnace at 550 °C for 5 h to obtain the metal composite oxide;

[0121] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of 15:3.2:4.5:2.3, add 300 mL of deionized water, and prepare solution C with the sum of the masses of each component being 10 g / L;

[0122] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly add the mixed solution B and solution C dropwise, and stir. During the addition process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue stirring and reacting at 60° C. for 6 hours. Then, let it stand for 24 hours, filter, wash several times, dry at 105° C. for 24 hours, and place it in a muffle furnace for calcination at 550° C. for 5 hours to obtain the methanation catalyst 8.

[0123] Preparation Example 9

[0124] Ni in the quaternary hydrotalcite precursor 2+ :Zr 2+ :Fe 3+ :Al 3+ The molar ratio is 5:1:1:1, the mass content of Mo, La and Ce modifiers is 10%, and the molar ratio of Mo, La and Ce in the modifier is 2:2:1.

[0125] (1) Weigh zirconium sulfate hexahydrate, iron nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare a solution A in which the mass and concentration of each component is 40 g / L;

[0126] (2) weighing hydroxide and dissolving it in deionized water to obtain a solution B with a concentration of 1 mol / L;

[0127] (3) Solution A and solution B were slowly dripped into a four-necked flask and stirred. During the addition process, the pH value of the mixed solution was controlled at 9.0-10. After completion, the mixture was stirred and reacted at 60° C. for 6 h. After standing for 24 h, the mixture was filtered, washed several times, and dried at 105° C. for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH). The mixture was then placed in a muffle furnace and calcined at 550° C. for 5 h to obtain a metal composite oxide.

[0128] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni, Mo, La, and Ce of 10:3.2:4.5:2.3, add 300 mL of deionized water, and prepare a solution C with a total mass of each component of 10 g / L;

[0129] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly add the mixed solution B and solution C dropwise, and stir. During the addition process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue stirring and reacting at 60° C. for 6 hours, then let it stand for 24 hours, filter, wash several times, dry at 105° C. for 24 hours, and place in a muffle furnace for calcination at 550° C. for 5 hours to obtain the methanation catalyst 9.

[0130] Preparation Example 10

[0131] The Ni in the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)) 2+ :Zr 2+ :Fe 3+ :Al 3+ The molar ratio is 5:1:1:1, the mass of Mo, La and Ce modifiers accounts for 10% of the mass of the catalyst, and the molar ratio of Mo, La and Ce in the modifier is 2:2:1.

[0132] (1) Weigh zirconium sulfate hexahydrate, iron nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare a solution A in which the mass and concentration of each component are 50 g / L;

[0133] (2) Weigh sodium hydroxide and dissolve it in deionized water to obtain a solution B with a concentration of 2 mol / L;

[0134] (3) Solution A and solution B were slowly dripped into a four-necked flask and stirred. During the addition process, the pH value of the mixed solution was controlled at 9.0-10. After completion, the mixture was stirred and reacted at 60° C. for 6 h. After standing for 24 h, the mixture was filtered, washed several times, and dried at 105° C. for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH). The mixture was then placed in a muffle furnace and calcined at 550° C. for 5 h to obtain a metal composite oxide.

[0135] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni, Mo, La, and Ce of 6.7:3.2:4.5:2.3, add 300 mL of deionized water, and prepare a solution C with a total mass of each component of 10 g / L;

[0136] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly add the mixed solution B and solution C dropwise, and stir. During the addition process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue stirring and reacting at 60° C. for 6 hours, then let it stand for 24 hours, filter, wash several times, dry at 105° C. for 24 hours, and place in a muffle furnace for calcination at 550° C. for 5 hours to obtain the methanation catalyst 10.

[0137] Preparation Example 11

[0138] The Ni in the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)) 2+ :Zr 2+ :Fe 3+ :Al 3+ The molar ratio is 5:1:1:1, and the mass of Mo, La, and Ce modifiers accounts for 10% of the mass of the catalyst.

[0139] (1) Weigh zirconium sulfate hexahydrate, iron nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare a solution A in which the mass and concentration of each component is 60 g / L;

[0140] (2) Weigh sodium hydroxide and dissolve it in deionized water to obtain a solution B with a concentration of 3 mol / L;

[0141] (3) Solution A and solution B were slowly dripped into a four-necked flask and stirred. During the addition process, the pH value of the mixed solution was controlled at 9.0-10. After completion, the mixture was stirred and reacted at 60° C. for 6 h. After standing for 24 h, the mixture was filtered, washed several times, and dried at 105° C. for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH). The mixture was then placed in a muffle furnace and calcined at 550° C. for 5 h to obtain a metal composite oxide.

[0142] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni, Mo, La, and Ce of 5:3.2:4.5:2.3, add 300 mL of deionized water, and prepare a solution C with a total mass of each component of 10 g / L;

[0143] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly add the mixed solution B and solution C dropwise, and stir. During the addition process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue stirring and reacting at 60° C. for 6 hours. Then, let it stand for 24 hours, filter, wash several times, dry at 105° C. for 24 hours, and place it in a muffle furnace for calcination at 550° C. for 5 hours to obtain the methanation catalyst 11.

[0144] Preparation Example 12

[0145] The Ni in the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)) 2+ :Zr 2+ :Fe 3+ :Al 3+ The molar ratio is 5:1:1:1, the mass of Mo, La and Ce modifiers accounts for 10% of the mass of the catalyst, and the molar ratio of Mo, La and Ce in the modifier is 2:2:1.

[0146] (1) Weigh zirconium nitrate pentahydrate, iron nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare a solution A in which the mass and concentration of each component is 40 g / L;

[0147] (2) Weigh sodium carbonate and dissolve it in deionized water to obtain a solution B with a concentration of 1 mol / L;

[0148] (3) Solution A and solution B were slowly dripped into a four-necked flask and stirred. During the addition process, the pH value of the mixed solution was controlled at 9.0-10. After completion, the mixture was stirred and reacted at 60° C. for 6 h. After standing for 24 h, the mixture was filtered, washed several times, and dried at 120° C. for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH). The mixture was then placed in a muffle furnace and calcined at 600° C. for 6 h to obtain a metal composite oxide.

[0149] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni, Mo, La, and Ce of 10:3.2:4.5:2.3, add 300 mL of deionized water, and prepare a solution C with a total mass of each component of 10 g / L;

[0150] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly add the mixed solution B and solution C dropwise, and stir. During the addition process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue stirring and reacting at 60° C. for 6 hours. Then, let it stand for 24 hours, filter, wash several times, dry at 120° C. for 24 hours, and place it in a muffle furnace for calcination at 600° C. for 6 hours to obtain the methanation catalyst 12.

[0151] Preparation Example 13

[0152] The Ni in the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)) 2+ :Zr 2+ :Fe 3+ :Al 3+ The molar ratio is 5:1:1:1, the mass of Mo, La and Ce modifiers accounts for 10% of the mass of the catalyst, and the molar ratio of Mo, La and Ce in the modifier is 2:2:1.

[0153] (1) Weigh zirconium sulfate pentahydrate, ferric chloride, nickel sulfate heptahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare a solution A in which the mass and concentration of each component is 40 g / L;

[0154] (2) Weigh concentrated ammonia water (68%) and add deionized water to obtain solution B with a concentration of 1 mol / L;

[0155] (3) Solution A and solution B were slowly dripped into a four-necked flask and stirred. During the addition process, the pH value of the mixed solution was controlled at 9.0-10. After completion, the mixture was stirred and reacted at 60° C. for 3 h. After standing for 12 h, the mixture was filtered, washed several times, and dried at 80° C. for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH). The mixture was then placed in a muffle furnace and calcined at 400° C. for 3 h to obtain a metal composite oxide.

[0156] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni, Mo, La, and Ce of 10:3.2:4.5:2.3, add 300 mL of deionized water, and prepare a solution C with a total mass of each component of 10 g / L;

[0157] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly add the mixed solution B and solution C dropwise, and stir. During the addition process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue to stir and react at 60°C for 3 hours, then let it stand for 12 hours, filter, wash several times, dry at 80°C for 24 hours, and place in a muffle furnace for calcination at 400°C for 3 hours to obtain the methanation catalyst 13.

[0158] Preparation Example 14

[0159] The Ni in the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)) 2+ :Zr 2+ :Fe 3+ :Al 3+ The molar ratio is 5:1:1:1, the mass of Mo, La and Ce modifiers accounts for 10% of the mass of the catalyst, and the molar ratio of Mo, La and Ce in the modifier is 2:2:1.

[0160] (1) Weigh zirconium nitrate pentahydrate, iron nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare a solution A in which the mass and concentration of each component is 40 g / L;

[0161] (2) Weigh sodium oxide and dissolve it in deionized water to obtain a solution B with a concentration of 1 mol / L;

[0162] (3) Solution A and solution B were slowly dripped into a four-necked flask and stirred. During the addition process, the pH value of the mixed solution was controlled at 9.0-10. After completion, the reaction was continued at 60° C. with stirring for 4.5 h. After standing for 16 h, the mixture was filtered, washed several times, and dried at 100° C. for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH). The mixture was then placed in a muffle furnace and calcined at 500° C. for 5 h to obtain a metal composite oxide.

[0163] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni, Mo, La, and Ce of 10:3.2:4.5:2.3, add 300 mL of deionized water, and prepare a solution C with a total mass of each component of 10 g / L;

[0164] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly add the mixed solution B and solution C dropwise, and stir. During the addition process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue stirring and reacting at 60° C. for 6 hours. Then, let it stand for 24 hours, filter, wash several times, dry at 120° C. for 24 hours, and place it in a muffle furnace for calcination at 600° C. for 6 hours to obtain the methanation catalyst 14.

[0165] Preparation Example 15

[0166] The Ni in the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)) 2+ :Zr 2+ :Fe 3+ :Al 3+ The molar ratio is 5:1:1:1, the mass of Mo, La and Ce modifiers accounts for 10% of the mass of the catalyst, and the molar ratio of Mo, La and Ce in the modifier is 2:2:1.

[0167] (1) Weigh zirconium nitrate pentahydrate, iron nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare a solution A in which the mass and concentration of each component is 40 g / L;

[0168] (2) Weigh sodium hydroxide and dissolve it in deionized water to obtain a solution B with a concentration of 1 mol / L;

[0169] (3) Solution A and solution B were slowly dripped into a four-necked flask and stirred. During the addition process, the pH value of the mixed solution was controlled at 9.0-10. After completion, the mixture was stirred and reacted at 60° C. for 6 h. After standing for 24 h, the mixture was filtered, washed several times, and dried at 120° C. for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH). The mixture was then placed in a muffle furnace and calcined at 600° C. for 6 h to obtain a metal composite oxide.

[0170] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni, Mo, La, and Ce of 10:3.2:4.5:2.3, add 300 mL of deionized water, and prepare a solution C with a total mass of each component of 10 g / L;

[0171] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly add the mixed solution B and solution C dropwise, and stir. During the addition process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue stirring and reacting at 60° C. for 4.5 hours, then let it stand for 16 hours, filter, wash several times, dry at 100° C. for 24 hours, and place in a muffle furnace for calcination at 500° C. for 5 hours to obtain the methanation catalyst 15.

[0172] Preparation Example 16

[0173] The Ni in the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)) 2+ :Zr 2+ :Fe 3+ :Al 3+ The molar ratio is 5:1:1:1, the mass of Mo, La and Ce modifiers accounts for 10% of the mass of the catalyst, and the molar ratio of Mo, La and Ce in the modifier is 2:2:1.

[0174] (1) Weigh zirconium nitrate pentahydrate, iron nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare a solution A in which the mass and concentration of each component is 40 g / L;

[0175] (2) Weigh sodium hydroxide and dissolve it in deionized water to obtain a solution B with a concentration of 1 mol / L;

[0176] (3) Solution A and solution B were slowly dripped into a four-necked flask and stirred. During the addition process, the pH value of the mixed solution was controlled at 9.0-10. After completion, the reaction was continued at 60° C. with stirring for 4.5 h. After standing for 16 h, the mixture was filtered, washed several times, and dried at 100° C. for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH). The mixture was then placed in a muffle furnace and calcined at 500° C. for 5 h to obtain a metal composite oxide.

[0177] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of the modifier contained in the catalyst, add 300 mL of deionized water, and prepare a solution C with a mass sum of each component of 10 g / L;

[0178] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly add the mixed solution B and solution C dropwise, and stir. During the addition process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue stirring and reacting at 60° C. for 4.5 hours, then let it stand for 16 hours, filter, wash several times, dry at 100° C. for 24 hours, and place in a muffle furnace for calcination at 500° C. for 5 hours to obtain the methanation catalyst 16.

[0179] Preparation Example 17

[0180] The Ni in the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)) 2+ :Zr 2+ :Fe 3+ :Al 3+The molar ratio is 5:1:1:1, the mass of Mo, La and Ce modifiers accounts for 10% of the mass of the catalyst, and the molar ratio of Mo, La and Ce in the modifier is 2:2:1.

[0181] (1) Weigh zirconium nitrate pentahydrate, iron nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare a solution A in which the mass and concentration of each component is 40 g / L;

[0182] (2) Weigh sodium hydroxide and dissolve it in deionized water to obtain a solution B with a concentration of 1 mol / L;

[0183] (3) Solution A and solution B were slowly dripped into a four-necked flask and stirred. During the addition process, the pH value of the mixed solution was controlled at 9.0-10. After completion, the mixture was stirred and reacted at 60° C. for 6 h. After standing for 20 h, the mixture was filtered, washed several times, and dried at 120° C. for 24 h to obtain a nickel-based quaternary hydrotalcite (NiZrFeAl-LDH). The mixture was then placed in a muffle furnace and calcined at 600° C. for 6 h to obtain a metal composite oxide.

[0184] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni, Mo, La, and Ce of 10:3.2:4.5:2.3, add 300 mL of deionized water, and prepare a solution C with a total mass of each component of 10 g / L;

[0185] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly add the mixed solution B and solution C dropwise, and stir. During the addition process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue to stir and react at 60°C for 3 hours, then let it stand for 8 hours, filter, wash several times, dry at 80°C for 24 hours, and place in a muffle furnace for calcination at 400°C for 3 hours to obtain the methanation catalyst 17.

[0186] Preparation Example 18

[0187] The Ni in the quaternary hydrotalcite precursor (i.e., nickel-based quaternary hydrotalcite (NiZrFeAl-LDH)) 2+ :Zr 2+ :Fe 3+ :Al 3+ The molar ratio is 5:1:1:1, the mass of Mo, La and Ce modifiers accounts for 10% of the mass of the catalyst, and the molar ratio of Mo, La and Ce in the modifier is 2:2:1.

[0188] (1) Weigh zirconium nitrate pentahydrate, iron nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add 300 mL of deionized water, and prepare a solution A in which the mass and concentration of each component is 40 g / L;

[0189] (2) Weigh sodium hydroxide and dissolve it in deionized water to obtain a solution B with a concentration of 1 mol / L;

[0190] (3) Solution A and solution B were slowly dripped into a four-necked flask and stirred. During the addition process, the pH value of the mixed solution was controlled at 9.0-10. After completion, the mixture was stirred and reacted at 60° C. for 3 h. After standing for 8 h, the mixture was filtered, washed several times, and dried at 80° C. for 24 h to obtain nickel-based quaternary hydrotalcite (NiZrFeAl-LDH). The mixture was then placed in a muffle furnace and calcined at 400° C. for 3 h to obtain a metal composite oxide.

[0191] (4) Weigh a certain amount of soluble salts of Ni, Mo, La, and Ce according to the mass ratio of Ni, Mo, La, and Ce of 10:3.2:4.5:2.3, add deionized water, and prepare a solution C with a total mass of each component of 10 g / L;

[0192] (5) Pour the metal composite oxide obtained in step (3) into deionized water, slowly add the mixed solution B and solution C dropwise, and stir. During the addition process, control the pH value of the mixed solution to be between 9.0 and 10. After completion, continue stirring and reacting at 60° C. for 6 hours. Then, let it stand for 24 hours, filter, wash several times, dry at 120° C. for 24 hours, and place in a muffle furnace for calcination at 600° C. for 6 hours to obtain the methanation catalyst 18.

[0193] Preparation Comparative Example 1

[0194] The molar ratio of Ni, Mg and Al constituting the catalyst is: 3:1:1

[0195] (1) Weighing soluble salts of magnesium nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, adding deionized water, and preparing a solution A with a mass sum of each component and a concentration of 30 g / L;

[0196] (2) Weigh sodium hydroxide and dissolve it in deionized water to obtain a solution B with a concentration of 1 mol / L;

[0197] (3) Solution A and solution B were mixed at 60°C, and the mixture was poured into a reactor. The mixture was stirred and reacted at 60°C for 6 h. After standing for 3 h, it was filtered. The precipitate was washed with deionized water, dried at 70°C for 6 h, and calcined in a muffle furnace at 550°C for 5 h to obtain catalyst 19.

[0198] Preparation Comparative Example 2

[0199] The mass ratio of Ni and Al constituting the catalyst is: 3:1

[0200] (1) Weighing soluble salts of nickel nitrate hexahydrate and aluminum nitrate nonahydrate in proportion, adding deionized water, and preparing a solution A with a total mass of each component and a concentration of 30 g / L;

[0201] (2) Weigh sodium hydroxide and dissolve it in deionized water to obtain a solution B with a concentration of 2 mol / L;

[0202] (3) Solution A and Solution B were mixed at room temperature, and the mixture was poured into a reactor. The mixture was stirred and reacted at 60°C for 6 h. After standing for 3 h, it was filtered. The precipitate was washed with deionized water, dried at 70°C for 6 h, and calcined in a muffle furnace at 450°C for 5 h to obtain catalyst 20.

[0203] Preparation Comparative Example 3

[0204] The molar ratio of Ni, Fe and Al constituting the catalyst is: 2:1:1

[0205] (1) Weigh soluble salts of ferric nitrate hexahydrate, nickel nitrate hexahydrate, and aluminum nitrate nonahydrate in proportion, add deionized water, and prepare a solution A with a mass sum of each component and a concentration of 30 g / L;

[0206] (2) Weigh sodium hydroxide and dissolve it in deionized water to obtain a solution B with a concentration of 1 mol / L;

[0207] (3) At 60°C, solution A and solution B were mixed, and the mixture was poured into a reactor. The pH value of the mixed solution was controlled to be 9. The mixture was stirred at 60°C for 6 h, and then filtered after standing for 3 h. The precipitate was washed with deionized water, dried at 70°C for 6 h, and calcined in a muffle furnace at 550°C for 5 h to obtain catalyst 21.

[0208] 2. Catalyst Structure Test Example

[0209] Structural Test Example 1: X-ray Diffraction Test

[0210] X-ray powder diffraction (XRD) was used to analyze the phase and crystallinity of the samples. A Bruker D8 Advance X-ray powder diffractometer was used with Cu Kα as the radiation source, a wavelength of 0.154 nm, a radiation voltage and current of 40 kV and 100 mA, respectively, and a scanning rate of 20 ° min -1 , step size was 0.02°, scanning range was 2θ=5~80°, and catalyst 1 was tested.

[0211] The test results are as follows Figure 2 As shown, the X-ray diffraction curves of the quaternary hydrotalcite and its oxide in the methanation catalyst 1 obtained in Example 1 are shown. The figure shows that the obtained quaternary hydrotalcite and its oxide have a typical two-dimensional layered structure.

[0212] Structural Test Example 2: Fourier Transform Infrared Spectroscopy Test

[0213] Fourier transform infrared spectroscopy (FT-IR) characterization was performed on Catalyst 1 using a Nexus 870 FT-IR spectrometer.

[0214] Test results such as Figure 2 As shown, the Fourier transform infrared spectrum curve of the quaternary hydrotalcite and its oxide in the methanation catalyst 1 obtained in Example 1 is shown, and the characteristic peak absorption signals at 3460cm-1 and 1634cm-1 are attributed to the stretching vibration of the absorbed water and hydroxyl groups, and the peaks at 1465cm-1 and 1377cm-1 can be attributed to the undecomposed NO3-. Structural Test Example 3: N 2 Adsorption-desorption test

[0215] The specific surface area and pore size (BET) were determined using a Micromeritics ASAP 2020 fully automatic specific surface area and porosity analyzer. 0.1 g of sample was weighed for nitrogen physical adsorption-desorption experiments. The sample was pretreated at 120 °C under vacuum for 4 h and then N was completely removed under -196 °C liquid nitrogen conditions. 2 Adsorption-desorption test was carried out on catalyst 1 (NiZrFeAlO) and its precursor (NiZrFeAl-LDH).

[0216] Test results such as Figure 3 As shown in Table 3, Figure 3 The N of the catalyst precursor and the catalyst 1 in the methanation catalyst 1 obtained in Example 1 is shown. 2 Adsorption-desorption curve: It can be seen from the figure that the hysteresis curves of the precursor and the catalyst are both obvious H3-type hysteresis lines, and there is no obvious saturated adsorption platform, which is a typical mesoporous material.

[0217] Table 3 Specific surface area of ​​quaternary hydrotalcite and its oxides

[0218]

[0219] Table 3 is through N 2 Comparison of the specific surface area, pore volume and pore size obtained after adsorption-desorption tests showed that the catalyst obtained after calcination had higher specific surface area, pore volume and pore size than its precursor.

[0220] 3. Catalyst Performance Test Example

[0221] Performance Test Example 1: Performance test of catalyst 1 prepared in Preparation Example 1

[0222] Test method: The catalyst methanation performance evaluation was carried out in a pressurized fixed bed reactor (reactor bed 2×11 cm, upper and lower fillers are quartz sand, filler height is 5 cm each, catalyst bed height is 1 cm), the amount of methanation catalyst is 5 g, first the fixed bed temperature is raised to 400 ° C, and after the temperature stabilizes, N 2 Replace the air in the reaction device 3 times and replace it with H 2 The catalyst was reduced in situ under a hydrogen pressure of 4 MPa for 4 h. After the reduction was completed, the valve was closed and N 2 Replace the H in the reactor 2 3 times. Then the reactor temperature was raised to 450°C and the raw material gas was introduced. The raw material composition (volume percentage) was: CO 5.8%, CO 2 2%, H 2 59.6%, CH 4 24.1%, O 2 0.6%, H 2 S 0.1%, the rest N 2 .

[0223] Test conditions: airspeed 6000h -1 , pressure 2MPa, reaction temperature 450℃, after the reaction stabilizes (2h), the post-reaction gas is analyzed online.

[0224] Test results: After testing, CO and CO 2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. 2 The conversion rates of CH 4 The selectivity was above 99% and the activity of the catalyst did not decrease significantly.

[0225] Performance Test Example 2: Performance test of catalyst 2 prepared in Preparation Example 2

[0226] The test method and test conditions are the same as those in Performance Test Example 1.

[0227] Test results: After testing, CO and CO 2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. 2 The conversion rates of CH 4 The selectivity was above 99% and the activity of the catalyst did not decrease significantly.

[0228] Performance Test Example 3: Performance test of catalyst 3 prepared in Preparation Example 3

[0229] The test method and test conditions are the same as those in Performance Test Example 1.

[0230] Test results: After testing, CO and CO 2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. 2 The conversion rates of CH 4 The selectivity was above 99% and the activity of the catalyst did not decrease significantly.

[0231] Performance Test Example 4: Performance Test of Catalyst 4 Prepared in Preparation Example 4

[0232] The test method and test conditions are the same as those in Performance Test Example 1.

[0233] Test results: After testing, CO and CO 2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. After the catalyst continued to operate for 100 hours under the same conditions, 2 The conversion rates of CH 4 The selectivity was above 99% and the activity of the catalyst did not decrease significantly.

[0234] Performance Test Example 5: Performance test of catalyst 5 prepared in Preparation Example 5

[0235] The test method and test conditions are the same as those in Performance Test Example 1.

[0236] Test results: After testing, CO and CO 2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. 2 The conversion rates of CH 4 The selectivity was above 99% and the activity of the catalyst did not decrease significantly.

[0237] Performance Test Example 6: Performance Test of Catalyst 6 Prepared in Preparation Example 6

[0238] The test method and test conditions are the same as those in Performance Test Example 1.

[0239] Test results: After testing, CO and CO2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. After the catalyst was operated for 100 hours under the same conditions, 2 The conversion rates of CH 4 The selectivity was above 99% and the activity of the catalyst did not decrease significantly.

[0240] Performance Test Example 7: Performance test of catalyst 7 prepared in Preparation Example 7

[0241] The test method and test conditions are the same as those in Performance Test Example 1.

[0242] Test results: After testing, CO and CO 2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. After the catalyst was used for 100 hours under the same conditions, 2 The conversion rates of CH 4 The selectivity was above 99% and the activity of the catalyst did not decrease significantly.

[0243] Performance Test Example 8: Performance test of catalyst 8 prepared in Preparation Example 8

[0244] The test method and test conditions are the same as those in Performance Test Example 1.

[0245] Test results: After testing, CO and CO 2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. 2 The conversion rates of CH 4 The selectivity was above 99% and the activity of the catalyst did not decrease significantly.

[0246] Performance Test Example 9: Performance test of catalyst 9 prepared in Preparation Example 9

[0247] The test method and test conditions are the same as those in Performance Test Example 1.

[0248] Test results: After testing, CO and CO 2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. After the catalyst was used for 100 hours under the same conditions, 2 The conversion rates of CH 4The selectivity was above 99% and the activity of the catalyst did not decrease significantly.

[0249] Performance Test Example 10: Performance test of catalyst 10 prepared in Preparation Example 10

[0250] The test method and test conditions are the same as those in Performance Test Example 1.

[0251] Test results: After testing, CO and CO 2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. 2 The conversion rates of CH 4 The selectivity was above 99% and the activity of the catalyst did not decrease significantly.

[0252] Performance Test Example 11: Performance test of catalyst 11 prepared in Preparation Example 11

[0253] The test method and test conditions are the same as those in Performance Test Example 1.

[0254] Test results: After testing, CO and CO 2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. After the catalyst was operated for 100 hours under the same conditions, 2 The conversion rates of CH 4 The selectivity was above 99% and the activity of the catalyst did not decrease significantly.

[0255] Performance Test Example 12: Performance Test of Catalyst 19 Prepared in Comparative Example 1

[0256] The test method and test conditions are the same as those in Performance Test Example 1.

[0257] Test results: After testing, CO and CO 2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. After the catalyst was used for 100 hours under the same conditions, 2 The conversion rates of CH 4 The selectivity was 90.5%, and the activity of the catalyst decreased significantly.

[0258] Performance Test Example 13: Performance Test of Catalyst 20 Prepared in Comparative Example 2

[0259] The test method and test conditions are the same as those in Performance Test Example 1.

[0260] Test results: After testing, CO and CO 2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. After the catalyst was used for 100 hours under the same conditions, 2 The conversion rates of CH 4 The selectivity was 83.2%, and the activity of the catalyst decreased significantly.

[0261] Performance Test Example 14: Performance Test of Catalyst 21 Prepared in Comparative Example 3

[0262] The test method and test conditions are the same as those in Performance Test Example 1.

[0263] Test results: After testing, CO and CO 2 The conversion rates of CH 4 The selectivity of CO and CO was above 99%. After the catalyst was used for 100 hours under the same conditions, 2 The conversion rates of CH 4 The selectivity was 89.6%, and the activity of the catalyst decreased significantly.

[0264] Results analysis: From the above performance test examples, it can be seen that after the catalyst prepared by the method provided by the present invention is operated for 100 hours under sulfur-containing conditions, the catalyst still maintains good catalytic activity and CH 4 Selectivity, CO and CO 2 The conversion rate of CH 4 The selectivity reached 99.9%. After the reaction was continuously run for 100 hours, the activity of the catalyst did not show a significant decrease. However, the catalysts prepared in Comparative Examples 1, 2 and 3 were traditional methane catalysts without adding modifiers. After the methanation reaction test under sulfur-containing conditions, CO and CO 2 The conversion rates have dropped significantly.

Claims

1. A modified Ni / Zr / Fe / Al hydrotalcite catalyst, characterized in that: NiZrFeAl quaternary hydrotalcite is used as a precursor, and Mo, La, and Ce are added as modifiers for modification to obtain a modified Ni / Zr / Fe / Al hydrotalcite catalyst; the modified Ni / Zr / Fe / Al hydrotalcite catalyst is obtained by the following preparation steps: S1, dissolving nickel salt, aluminum salt, zirconium salt and iron salt in deionized water to prepare solution A; S2, dissolving the alkaline solution in deionized water to prepare solution B; S3, adding solution A and solution B to deionized water for mixing, adjusting the pH value to 9.0-10.0 for reaction, and after the reaction is completed, performing an aging treatment on the reaction precipitate; then filtering, washing, and drying the obtained product to obtain a catalyst precursor; and then performing a calcination treatment on the catalyst precursor; S4, dissolving nickel salt and a modifier in deionized water to prepare a solution C; the modifier is a molybdenum salt, a cerium salt, or a lanthanum salt; S5, mixing solution B, solution C, and the product obtained in S3, adjusting the pH value to 9.0-10.0 for reaction, and performing aging treatment on the reaction precipitate after the reaction is completed; then filtering, washing, and drying the obtained product to obtain a modified catalyst precursor; The modified catalyst precursor is then calcined to obtain a modified Ni / Zr / Fe / Al hydrotalcite catalyst; Wherein, based on the mass of the catalyst as 100%, the mass content of the Ni component is 20-70%, the mass content of the Zr component is 10-40%, the mass content of the Fe component is 5-40%, the mass content of the Al component is 5-40%, the total mass content of the modifier is 5-15%, and the mass ratio of Mo, La and Ce is (2-4):(4-5):(2-3).

2. The catalyst according to claim 1, characterized in that Taking the mass of the catalyst as 100%, the mass content of the Ni component is 50-55%, the mass content of the Zr component is 18-20%, the mass content of the Fe component is 10-12%, the mass content of the Al component is 4-6%, the mass content of the Mo component is 2-4%, the mass content of the La component is 3-5%, and the mass content of the Ce component is 2-4%.

3. The catalyst according to claim 1, characterized in that Taking the mass of the catalyst as 100%, the mass content of the Ni component is 52.7%, the mass content of the Zr component is 19.5%, the mass content of the Fe component is 11.99%, the mass content of the Al component is 5.78%, the mass content of the Mo component is 3.14%, the mass content of the La component is 4.55%, and the mass content of the Ce component is 2.31%.

4. A method for preparing a modified Ni / Zr / Fe / Al hydrotalcite catalyst, characterized in that: The preparation steps are: S1, dissolving nickel salt, aluminum salt, zirconium salt and iron salt in deionized water to prepare solution A; S2, dissolving the alkaline solution in deionized water to prepare solution B; S3, adding solution A and solution B to deionized water for mixing, adjusting the pH value to 9.0-10.0 for reaction, and after the reaction is completed, performing an aging treatment on the reaction precipitate; then filtering, washing, and drying the obtained product to obtain a catalyst precursor; and then performing a calcination treatment on the catalyst precursor; S4, dissolving nickel salt and a modifier in deionized water to prepare a solution C; the modifier is a molybdenum salt, a cerium salt, or a lanthanum salt; S5, mixing solution B, solution C, and the product obtained in S3, adjusting the pH value to 9.0-10.0 for reaction, and performing aging treatment on the reaction precipitate after the reaction is completed; then filtering, washing, and drying the obtained product to obtain a modified catalyst precursor; The modified catalyst precursor is then calcined to obtain a modified Ni / Zr / Fe / Al hydrotalcite catalyst; Wherein, based on the mass of the catalyst as 100%, the mass content of the Ni component is 20-70%, the mass content of the Zr component is 10-40%, the mass content of the Fe component is 5-40%, the mass content of the Al component is 5-40%, the total mass content of the modifier is 5-15%, and the mass ratio of Mo, La and Ce is (2-4):(4-5):(2-3).

5. The preparation method according to claim 4, characterized in that: The nickel salt in S1 is any one of nickel nitrate, nickel sulfate, nickel chloride or nickel acetate, or a mixture of at least two of them; the aluminum salt in S1 is any one of aluminum nitrate, aluminum sulfate, aluminum chloride or aluminum acetate, or a mixture of at least two of them; the zirconium salt in S1 is any one of zirconium nitrate and zirconium sulfate, or a mixture of at least two of them; the iron salt in S1 is any one of iron nitrate, iron chloride or iron sulfate, or a mixture of at least two of them; the Ni in solution A in S1 is 2+ :Zr 2+ :Fe 3+ :Al 3+ The molar content ratio is (2~5):1:1:

1.

6. The preparation method according to claim 4, characterized in that: The alkaline solution in S2 is any one of sodium carbonate, sodium hydroxide, sodium bicarbonate, ammonia, potassium hydroxide, potassium carbonate or potassium bicarbonate, or a mixed solution of at least two of them; the nickel salt, molybdenum salt, cerium salt and lanthanum salt in S4 are nickel nitrate, molybdenum nitrate, cerium nitrate and lanthanum nitrate; the Ni in solution C in S4 is 2+ :Mo 4+ :La 3+ :Ce 4+ The molar content ratio is (8~35):(2~3):(1~2):

1.

7. The preparation method according to claim 4, characterized in that: The reaction time in S3 is 2 to 6 hours, and the aging treatment time is 6 to 24 hours; the drying treatment time in S3 is 12 to 24 hours, and the temperature is 60 to 120°C; the calcination treatment time in S3 is 3 to 6 hours, and the temperature is 400 to 600°C.

8. The preparation method according to claim 4, characterized in that: The reaction time in S5 is 3 to 6 hours, and the aging treatment time is 6 to 24 hours; the drying treatment time in S5 is 12 to 24 hours, and the temperature is 60 to 120° C.; the calcination treatment time in S5 is 3 to 6 hours, and the temperature is 400 to 600° C.

9. Use of the catalyst according to any one of claims 1 to 3 or the catalyst prepared by the preparation method according to any one of claims 4 to 8, characterized in that: The modified Ni / Zr / Fe / Al hydrotalcite catalyst was used to catalyze the methanation reaction of coke oven gas.

10. The use according to claim 9, characterized in that When the catalyst is used for catalytic coke oven gas methanation reaction, the modified Ni / Zr / Fe / Al hydrotalcite catalyst is loaded into a fixed bed reactor, and the reaction conditions are space velocity 6000~8000h -1 , pressure 2-4 MPa, reaction temperature 400-500°C, reaction time 2-4 h; Wherein, before the reaction, the catalyst is reduced in a hydrogen atmosphere, the reduction temperature is 300-500° C., and the reduction time is 4-6 hours.

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