Catalyst with ti o2-coated si o2 material as carrier, its preparation method and application in co2 methanation

Abstract

This invention relates to catalysts using TiO2-coated SiO2 as a support, their preparation methods, and their application in CO2 methanation. The catalyst composition is Ni / SiO2@TiO2-MO. x Ni is the active component of the catalyst; SiO2@TiO2 is a TiO2-coated SiO2 material; MO x The additives were added to the support. TiO2 was uniformly deposited on the SiO2 surface, solving the problem of the small specific surface area of ​​the pure TiO2 support and promoting the activation of CO2 by TiO2. A small amount of additives were uniformly dispersed on the catalyst surface, and most of the remaining nitrates were found in the mother liquor obtained by centrifugation. Ni-supported catalysts were used for the CO2 methanation reaction, exhibiting high activity and good stability. The CO2 methanation conversion rate reached 88%, and the stability test showed no deactivation after 200 hours, indicating promising industrial application prospects.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and more specifically, to a catalyst with TiO2-coated SiO2 material as a support, its preparation method, and its application in the field of CO2 methanation. Background Technology

[0002] Contemporary society's dependence on fossil fuels leads to the massive emission of CO2, a greenhouse gas, causing serious environmental problems and climate change. To address this issue and achieve carbon neutrality, it is necessary to develop renewable energy technologies to reduce fossil fuel use, as well as carbon capture, utilization, and storage technologies to reduce carbon emissions. Among these, CO2 methanation, as a promising CO2 utilization technology, has received widespread attention.

[0003] CO2 methanation can convert carbon dioxide into useful chemicals, thereby reducing atmospheric carbon dioxide concentration and playing a significant role in mitigating the greenhouse effect and protecting the environment. Simultaneously, this reaction can effectively address global warming by reducing greenhouse gas emissions. Secondly, CO2 methanation technology couples renewable energy with chemical energy, converting non-carbon energy into chemical energy and maximizing the utilization of renewable energy. It is also an effective way to address the high cost and instability of H2 storage and transportation, and the conversion of renewable energy into energy storage. This can alleviate my country's energy structure problems of oil and gas shortages and improve energy self-sufficiency. Furthermore, CO2 methanation can convert waste CO2 into high-value-added fuel CH4, enabling the effective recycling of carbon resources. This is crucial for achieving sustainable carbon resource utilization and promoting the development of a circular economy. In conclusion, CO2 methanation is significant in environmental protection and energy utilization, reducing carbon dioxide emissions, mitigating global warming, and simultaneously achieving the recycling of carbon resources and maximizing the utilization of renewable energy.

[0004] Currently, reported catalysts for CO2 methanation are those with metals such as Ru, Pt, Pd, Rh, Ni, Co, and Fe as active components. Among them, noble metal catalysts such as Ru and Rh exhibit excellent performance and good resistance to carbon deposition, but their high price limits their industrial application. Ni-based catalysts, on the other hand, possess relatively high activity and selectivity, are inexpensive, and readily available, thus showing potential for industrial application and attracting widespread attention from researchers. However, Ni-based catalysts still face some challenges limiting their industrial application. Firstly, because CO2 molecules are very stable and inert compounds, with carbon atoms in their highest oxidation state, they are difficult to activate at low temperatures. Therefore, improving the low-temperature activity of the catalyst is a key issue that needs to be addressed. Secondly, CO2 methanation is a strongly exothermic reaction, and Ni-based catalysts suffer from the problem of active metal sintering during the reaction.

[0005] The physicochemical properties of the support significantly influence the catalytic performance of the catalyst. Supports for CO2 methanation mainly include SiO2, Al2O3, ZrO2, TiO2, CeO2, etc. Among them, SiO2, as a conventional support, is inexpensive, readily available, and has a large specific surface area. However, its surface lacks active adsorption sites, exhibiting chemical inertness, and its performance in the CO2 methanation reaction is not very good. Ni / Al2O3 catalysts have been widely studied due to their good activity and mature technology. However, the main problem is that excessive loading can easily lead to sintering under prolonged high-temperature operation, accelerating catalyst deactivation; and due to the strong interaction between Ni and Al2O3, NiAl2O4 spinel phase is easily formed, resulting in the loss of active components. Reducible supports, represented by TiO2, have abundant chemisorption sites on their surface, which is very beneficial for improving the low-temperature activity of the methanation reaction; furthermore, the partial substitution of Ni in the TiO2 lattice can generate oxygen vacancies, further improving catalytic performance. However, compared to conventional supports, pure TiO2 has a lower specific surface area, which is not conducive to improving catalyst activity. Summary of the Invention

[0006] The purpose of this invention is to increase the specific surface area of ​​TiO2 support and overcome the problems of low activity and poor stability of existing CO2 methanation catalysts. It provides a catalyst with TiO2-coated SiO2 material as support and its preparation method. When used in CO2 methanation reaction, it exhibits good activity and anti-sintering properties.

[0007] To further improve the activity and stability of the catalyst, this invention utilizes the high specific surface area of ​​SiO2 to uniformly deposit TiO2 on the SiO2 surface, solving the problem of the small specific surface area of ​​pure TiO2 support and promoting the activation of CO2 by TiO2. During the TiO2 deposition process, excess nitrate is added to the solution to ensure that a small amount of nitrate is uniformly dispersed on the catalyst surface. Most of the nitrate remaining in the mother liquor obtained by centrifugation can be reused. The supported Ni, when used as a catalyst for the CO2 methanation reaction, exhibits both high activity and good stability.

[0008] To address the aforementioned objectives, the present invention provides the following technical solution:

[0009] The catalyst, with TiO2-coated SiO2 material as the support, has the composition Ni / SiO2@TiO2-MO. x Ni is the active component of the catalyst, accounting for 5-20% by mass; SiO2@TiO2 is a TiO2-coated SiO2 material that serves as the catalyst support; MO x The additives added to the carrier; according to the mass ratio, SiO2:TiO2:MOx = 1:(0.15~0.50):(0~0.50); ​​MO xIt can be La2O3, CeO2 or ZrO2.

[0010] in MO x With zero additives, the catalyst structure is: Ni / SiO2@TiO2.

[0011] in MO x Under conditions where the additive content is not zero, the catalyst structure is: Ni / SiO2@TiO2-MO x ; Preferred MO x According to the mass ratio, SiO2:TiO2:MO x =1:(0.15~0.50):(0.05~0.50).

[0012] The method for preparing the catalyst using TiO2-coated SiO2 material as a support according to the present invention includes the following steps:

[0013] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent to obtain a mixture with a silica mass concentration of 10-20 g / L.

[0014] 2) Add tetrabutyl titanate to the mixture obtained in step 1), and then add the corresponding nitrate of the auxiliary agent to the mixture. The molar ratio of tetrabutyl titanate: nitrate: fumed silica is 1:(0~5):(2.7~9.2). Stir for 1~6h. Add deionized water dropwise to the container at a feed rate of 0.1~1mL / min. The molar ratio of deionized water: tetrabutyl titanate is (2~4):1. A solid-liquid mixture is obtained.

[0015] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 60-120°C overnight;

[0016] 4) The solid dried in step 3) is calcined at 500–700℃ to obtain SiO2@TiO2 or SiO2@TiO2-MO. x ;

[0017] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:(1-3), and the concentration of nickel nitrate in the solution is 0.3-1.4 mol / L; add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with equal volume, seal and let stand for 12-48 h, place in an oven at 60-90℃ for 5-7 h, and then dry overnight at 100-150℃ to obtain the dried product;

[0018] 6) The dried product obtained in step 5) is calcined at 500-700℃ to obtain the catalyst precursor;

[0019] 7) Place the catalyst precursor obtained in step 6) in a reactor, introduce reducing gas into the reactor, and reduce the catalyst precursor; the reduction temperature is 400-700℃; to obtain the catalyst Ni / SiO2@TiO2 or Ni / SiO2@TiO2-MO. x .

[0020] The nitrates corresponding to the auxiliary agents in step 2) are lanthanum nitrate, cerium nitrate, or zirconium nitrate.

[0021] The product dried in step 4) is calcined at 500-700℃ for 2-6 hours, with a heating rate of 1-10℃ / min.

[0022] The product dried in step 6) is calcined at 500-700℃ for 2-6 hours, with a heating rate of 1-10℃ / min.

[0023] In step 7), a reducing gas flow rate of 10–30 mL / min is introduced, the reduction time is 1–3 h, the reduction temperature is 400–700 °C, and the heating rate is 1–10 °C / min.

[0024] The reducing gas in step 7) is hydrogen, carbon monoxide, or a mixture of an inert gas and one or two of hydrogen and carbon monoxide; the volume percentage of the inert gas in the mixed gas atmosphere is 1% to 99%.

[0025] The catalyst of the present invention, which uses TiO2-coated SiO2 material as a support, is applied to the CO2 methanation reaction.

[0026] The catalyst, with TiO2-coated SiO2 material as the support, is applied to the CO2 methanation reaction. Its characteristic is that the catalyst is added to a fixed-bed reactor, and carbon dioxide and hydrogen are introduced into the reactor at a volume hourly space velocity (VHSV) of 15000-60000 mL / (gcat h) under conditions of 200-500℃ and 0.1-5 MPa, wherein the molar ratio of carbon dioxide to hydrogen is 1:(1-5), to obtain the target product, methane.

[0027] As described above, the preparation method and application of the catalyst with TiO2-coated SiO2 material as support of the present invention have the following beneficial effects:

[0028] (1) This invention utilizes the high specific surface area of ​​gaseous SiO2 to prepare TiO2-coated SiO2 materials with a surface area as high as 195.1 μm. 2 With a specific surface area of ​​ / g, the Ni-based catalyst prepared using it as a support also boasts a specific surface area as high as 172.7m². 2 / g, overcoming the disadvantage of low specific surface area of ​​TiO2.

[0029] (2) The present invention adds an additive during the TiO2 deposition process, which effectively disperses the additive on the carrier surface, which is conducive to the additive playing a better role; and the mother liquor containing some nitrates obtained after centrifugation can be reused, which is economical and environmentally friendly.

[0030] (3) When the catalyst prepared in this invention is applied to the CO2 methanation reaction, it can exhibit good activity and stability. The conversion rate of the CO2 methanation reaction can reach 88%, and the stability test shows no deactivation after 200 hours, which has certain industrialization prospects. Attached Figure Description

[0031] Figure 1 The images show the X-ray diffraction (XRD) patterns of the catalysts after calcination in Examples 1-5.

[0032] Figure 2 The images are TEM images of (a) SiO2@TiO2 and (b) Ni / SiO2@TiO2 in Example 1.

[0033] Figure 3 The nitrogen adsorption-desorption isotherms and specific surface areas of SiO2, SiO2@TiO2 and Ni / SiO2@TiO2 used in Example 1 are shown. Figure 4 The results show the stability test results of the catalyst in the CO2 methanation reaction in Example 1. The reaction conditions were: H2:CO2 composition = 4:1, reaction pressure = 0.1 MPa, temperature = 350℃; and reaction space velocity = 15000 mL / (g). cat h). Detailed Implementation

[0034] Example 1

[0035] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 12 g / L.

[0036] 2) Add tetrabutyl titanate to the mixture obtained in step 1) according to the molar ratio of tetrabutyl titanate: fumed silica = 1:4.6, stir for 4 hours; add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min according to the molar ratio of deionized water: tetrabutyl titanate = 3:1;

[0037] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 80°C overnight.

[0038] 4) Calcine the solid dried in step 3) at 600℃ for 4 hours at a heating rate of 2℃ / min to obtain SiO2@TiO2 with a mass ratio of SiO2:TiO2 = 1:0.3.

[0039] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 24 hours, place it in an oven at 80°C for 6 hours, and then dry it overnight at 120°C to obtain the dried product.

[0040] 6) The dried product obtained in step 5) was calcined at 600℃ for 4h with a heating rate of 2℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2-600℃.

[0041] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2 h in H2 at a flow rate of 20 mL / min and a heating rate of 2℃ / min to obtain the catalyst Ni / SiO2@TiO2-600℃, with a Ni mass fraction of 12%. Figure 1 XRD patterns and Figure 2 The TEM images show that TiO2 is uniformly coated on the SiO2 surface without forming large grains; and the Ni, after loading, is also well dispersed on the support surface. Figure 3 The specific surface area test results show that the TiO2-coated SiO2 material has a surface area as high as 195.1 m². 2 With a specific surface area of ​​ / g, the Ni-based catalyst prepared using it as a support also boasts a specific surface area as high as 172.7m². 2 / g, the preparation method of the present invention achieves the goal of increasing the specific surface area of ​​TiO2.

[0042] 8) Add to the reactor at a volumetric hourly space velocity (VHSV) of 15000 mL / (g) cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0043] The catalytic performance of the CO2 hydrogenation methanation reaction under a pressure of 0.1 MPa is as follows:

[0044] At 250℃, the CO2 conversion rate was 19.2%, and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 83.6%, and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 81.5%, and the CH4 selectivity was 99.3%. The catalyst's stability was tested at 350℃. Figure 4 It can be seen that the catalyst does not show a trend of decreased activity within 200 hours, and has excellent stability.

[0045] The catalytic performance of the CO2 hydrogenation methanation reaction under a pressure of 1 MPa is as follows:

[0046] At 250℃, the CO2 conversion rate was 46.8% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 87.3% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 87.1% and the CH4 selectivity was 100%.

[0047] The catalytic performance of the CO2 hydrogenation methanation reaction under a pressure of 3 MPa is as follows:

[0048] At 250℃, the CO2 conversion rate was 57.6% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 88.9% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 88.6% and the CH4 selectivity was 100%.

[0049] Example 2

[0050] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 12 g / L.

[0051] 2) Add tetrabutyl titanate to the mixture obtained in step 1) with a molar ratio of tetrabutyl titanate: fumed silica = 1:4.6; add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min with a molar ratio of deionized water: tetrabutyl titanate = 3:1.

[0052] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 60°C overnight.

[0053] 4) Calcine the solid dried in step 3) at 500℃ for 3 hours at a heating rate of 5℃ / min to obtain SiO2@TiO2 with a mass ratio of SiO2:TiO2 = 1:0.3.

[0054] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 30 h, place it in an oven at 80 °C for 6 h, and then dry it overnight at 120 °C to obtain the dried product.

[0055] 6) The dried product obtained in step 5) is calcined at 500℃ for 3h with a heating rate of 5℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2-500℃.

[0056] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2 h in H2 at a flow rate of 20 mL / min and a heating rate of 2℃ / min to obtain the catalyst Ni / SiO2@TiO2-500℃, with a Ni mass fraction of 12%.

[0057] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0058] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0059] At 250℃, the CO2 conversion rate was 9.8% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 75.4% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 76.8% and the CH4 selectivity was 99.2%.

[0060] Example 3

[0061] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 10 g / L.

[0062] 2) Add tetrabutyl titanate to the mixture obtained in step 1), according to the molar ratio of tetrabutyl titanate: fumed silica = 1:4.6, add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min, according to the molar ratio of deionized water: tetrabutyl titanate = 3:1;

[0063] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 60°C overnight.

[0064] 4) Calcine the solid dried in step 3) at 550℃ for 4 hours at a heating rate of 2℃ / min to obtain SiO2@TiO2 with a mass ratio of SiO2:TiO2 = 1:0.3.

[0065] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 30 h, place it in an oven at 60 °C for 6 h, and then dry it at 100 °C overnight to obtain the dried product.

[0066] 6) The dried product obtained in step 5) was calcined at 550℃ for 4h at a heating rate of 2℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2-550℃.

[0067] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2 h in H2 at a flow rate of 20 mL / min and a heating rate of 2℃ / min to obtain the catalyst Ni / SiO2@TiO2-550℃, with a Ni mass fraction of 12%.

[0068] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0069] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0070] At 250℃, the CO2 conversion rate was 11.6% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 79.8% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 79.6% and the CH4 selectivity was 99.4%.

[0071] Example 4

[0072] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 10 g / L.

[0073] 2) Add tetrabutyl titanate to the mixture obtained in step 1) with a molar ratio of tetrabutyl titanate: fumed silica = 1:4.6; add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min with a molar ratio of deionized water: tetrabutyl titanate = 3:1.

[0074] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 80°C overnight.

[0075] 4) Calcine the solid dried in step 3) at 650℃ for 5h with a heating rate of 5℃ / min to obtain SiO2@TiO2. The mass ratio of SiO2:TiO2 is 1:0.3.

[0076] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 24 hours, place it in an oven at 80°C for 6 hours, and then dry it overnight at 120°C to obtain the dried product.

[0077] 6) The dried product obtained in step 5) was calcined at 650℃ for 5h with a heating rate of 5℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2-650℃.

[0078] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2 h in H2 at a flow rate of 20 mL / min and a heating rate of 2℃ / min to obtain the catalyst Ni / SiO2@TiO2-650℃, with a Ni mass fraction of 12%.

[0079] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0080] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0081] At 250℃, the CO2 conversion rate was 8.7% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 73.6% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 79.3% and the CH4 selectivity was 99.3%.

[0082] Example 5

[0083] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 10 g / L.

[0084] 2) Add tetrabutyl titanate to the mixture obtained in step 1) according to the molar ratio of tetrabutyl titanate: fumed silica = 1:4.6, stir for 4 hours; add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min according to the molar ratio of deionized water: tetrabutyl titanate = 3:1;

[0085] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 80°C overnight.

[0086] 4) Calcine the solid dried in step 3) at 600℃ for 4 hours at a heating rate of 2℃ / min to obtain SiO2@TiO2 with a mass ratio of SiO2:TiO2 = 1:0.3.

[0087] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 24 hours, place it in an oven at 80°C for 6 hours, and then dry it overnight at 120°C to obtain the dried product.

[0088] 6) The dried product obtained in step 5) was calcined at 700℃ for 4h at a heating rate of 2℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2-700℃.

[0089] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2 h in H2 at a flow rate of 20 mL / min and a heating rate of 2℃ / min to obtain the catalyst Ni / SiO2@TiO2-700℃, with a Ni mass fraction of 12%.

[0090] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0091] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0092] At 250℃, the CO2 conversion rate was 2.6% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 72.4% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 78.1% and the CH4 selectivity was 99.2%.

[0093] Example 6

[0094] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 10 g / L.

[0095] 2) Add tetrabutyl titanate to the mixture obtained in step 1) with a molar ratio of tetrabutyl titanate: fumed silica = 1:4.6; add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min with a molar ratio of deionized water: tetrabutyl titanate = 3:1.

[0096] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 80°C overnight.

[0097] 4) Calcine the solid dried in step 3) at 600℃ for 4 hours at a heating rate of 2℃ / min to obtain SiO2@TiO2 with a mass ratio of SiO2:TiO2 = 1:0.3.

[0098] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.3 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 24 hours, place it in an oven at 80°C for 6 hours, and then dry it overnight at 120°C to obtain the dried product.

[0099] 6) The dried product obtained in step 5) was calcined at 600℃ for 4h with a heating rate of 2℃ / min to obtain the catalyst precursor 5% NiO / SiO2@TiO2.

[0100] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500°C for 2 h in H2 at a flow rate of 20 mL / min and a heating rate of 2 °C / min to obtain the catalyst 5% Ni / SiO2@TiO2, with a Ni mass fraction of 5%.

[0101] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0102] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0103] At 250℃, the CO2 conversion rate was 9.7% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 69.2% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 71.4% and the CH4 selectivity was 99.3%.

[0104] Example 7

[0105] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 12 g / L.

[0106] 2) Add tetrabutyl titanate to the mixture obtained in step 1) with a molar ratio of tetrabutyl titanate: fumed silica = 1:4.6; add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min with a molar ratio of deionized water: tetrabutyl titanate = 3:1.

[0107] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 80°C overnight.

[0108] 4) Calcine the solid dried in step 3) at 600℃ for 4 hours at a heating rate of 2℃ / min to obtain SiO2@TiO2 with a mass ratio of SiO2:TiO2 = 1:0.3.

[0109] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 1.4 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 24 hours, place it in an oven at 80°C for 6 hours, and then dry it overnight at 120°C to obtain the dried product.

[0110] 6) The dried product obtained in step 5) was calcined at 600℃ for 4h with a heating rate of 2℃ / min to obtain the catalyst precursor 20% NiO / SiO2@TiO2.

[0111] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2h in H2 at a flow rate of 20mL / min and a heating rate of 2℃ / min to obtain the catalyst 20% Ni / SiO2@TiO2, with a Ni mass fraction of 20%.

[0112] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0113] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0114] At 250℃, the CO2 conversion rate was 10.0% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 74.7% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 75.8% and the CH4 selectivity was 99.4%.

[0115] Example 8

[0116] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 20 g / L.

[0117] 2) Add tetrabutyl titanate to the mixture obtained in step 1) with a molar ratio of tetrabutyl titanate: fumed silica = 1:9.2; add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min with a molar ratio of deionized water: tetrabutyl titanate = 3:1.

[0118] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 80°C overnight.

[0119] 4) The solid dried in step 3) is calcined at 600℃ for 4 hours at a heating rate of 2℃ / min to obtain SiO2@TiO2. The mass ratio of SiO2:TiO2 is 1:0.15.

[0120] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 24 hours, place it in an oven at 80°C for 6 hours, and then dry it overnight at 120°C to obtain the dried product.

[0121] 6) The dried product obtained in step 5) was calcined at 600℃ for 4h with a heating rate of 2℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2.

[0122] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2 h in H2 at a flow rate of 20 mL / min and a heating rate of 2℃ / min to obtain the catalyst Ni / SiO2@TiO2 with a Ni mass fraction of 12%.

[0123] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0124] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0125] At 250℃, the CO2 conversion rate was 17.6% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 81.2% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 83.0% and the CH4 selectivity was 99.4%.

[0126] Example 9

[0127] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 10 g / L.

[0128] 2) Add tetrabutyl titanate to the mixture obtained in step 1) with a molar ratio of tetrabutyl titanate: fumed silica = 1:2.7; add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min with a molar ratio of deionized water: tetrabutyl titanate = 3:1.

[0129] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 80°C overnight.

[0130] 4) Calcine the solid dried in step 3) at 600℃ for 4 hours at a heating rate of 2℃ / min to obtain SiO2@TiO2 with a mass ratio of SiO2:TiO2 = 1:0.5.

[0131] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 24 hours, place it in an oven at 80°C for 6 hours, and then dry it overnight at 120°C to obtain the dried product.

[0132] 6) The dried product obtained in step 5) was calcined at 600℃ for 4h with a heating rate of 2℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2.

[0133] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2 h in H2 at a flow rate of 20 mL / min and a heating rate of 2℃ / min to obtain the catalyst Ni / SiO2@TiO2 with a Ni mass fraction of 12%.

[0134] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0135] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0136] At 250℃, the CO2 conversion rate was 10.1% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 80.8% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 81.1% and the CH4 selectivity was 99.4%.

[0137] Example 10

[0138] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 20 g / L.

[0139] 2) Add tetrabutyl titanate to the mixture obtained in step 1) according to the molar ratio of tetrabutyl titanate: fumed silica = 1:4.6, stir for 1 hour; add deionized water dropwise to the beaker at a feed rate of 0.1 mL / min according to the molar ratio of deionized water: tetrabutyl titanate = 2:1;

[0140] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 60°C overnight.

[0141] 4) Calcine the solid dried in step 3) at 500℃ for 2 hours at a heating rate of 1℃ / min to obtain SiO2@TiO2 with a mass ratio of SiO2:TiO2 = 1:0.3.

[0142] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1, and the molar concentration of nickel nitrate is 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 12 hours, place it in an oven at 60°C for 5 hours, and then dry it at 100°C overnight to obtain the dried product NiO / SiO2@TiO2.

[0143] 6) The dried product obtained in step 5) is calcined at 600℃ for 2h at a heating rate of 1℃ / min to obtain the catalyst precursor.

[0144] 7) The obtained catalyst precursor was placed in a reactor and reduced at 400℃ for 1h in 1% H2 / He at a flow rate of 10mL / min and a heating rate of 1℃ / min to obtain the catalyst Ni / SiO2@TiO2, with a Ni mass fraction of 12%.

[0145] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 30000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:1.

[0146] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0147] At 250℃, the CO2 conversion rate was 10.3% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 65.8% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 73.4% and the CH4 selectivity was 67.8%.

[0148] Example 11

[0149] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 20 g / L.

[0150] 2) Add tetrabutyl titanate to the mixture obtained in step 1) according to the molar ratio of tetrabutyl titanate: fumed silica = 1:4.6, and stir for 6 hours; add deionized water dropwise to the beaker at a feed rate of 1 mL / min according to the molar ratio of deionized water: tetrabutyl titanate = 4:1.

[0151] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 120°C overnight.

[0152] 4) The solid dried in step 3) is calcined at 700℃ for 6 hours at a heating rate of 10℃ / min to obtain SiO2@TiO2. The mass ratio of SiO2:TiO2 is 1:0.3.

[0153] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:3, and the molar concentration of nickel nitrate is 0.77 mol / L; add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with equal volume, seal and let stand for 24 h, place in an oven at 90 °C for 7 h, and then dry at 150 °C overnight to obtain the dried product.

[0154] 6) The dried product obtained in step 5) was calcined at 600℃ for 6h with a heating rate of 10℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2.

[0155] 7) The obtained catalyst precursor was placed in a reactor and reduced at 700°C for 3 h in 99% H2 / He at a flow rate of 30 mL / min and a heating rate of 10 °C / min to obtain the catalyst Ni / SiO2@TiO2, with a Ni mass fraction of 12%.

[0156] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 60,000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:5.

[0157] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0158] At 250℃, the CO2 conversion rate was 7.2% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 52.8% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 70.4% and the CH4 selectivity was 85.1%; and at 600℃, the CO2 conversion rate was 61.2% and the CH4 selectivity was 42.4%.

[0159] Example 12

[0160] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 15 g / L.

[0161] 2) Add tetrabutyl titanate to the mixture obtained in step 1) with a molar ratio of tetrabutyl titanate: fumed silica = 1:4.6; add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min with a molar ratio of deionized water: tetrabutyl titanate = 3:1.

[0162] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 80°C overnight.

[0163] 4) Calcine the solid dried in step 3) at 600℃ for 4 hours at a heating rate of 2℃ / min to obtain SiO2@TiO2 with a mass ratio of SiO2:TiO2 = 1:0.3.

[0164] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 24 hours, place it in an oven at 80°C for 6 hours, and then dry it overnight at 120°C to obtain the dried product.

[0165] 6) The dried product obtained in step 5) was calcined at 600℃ for 4h with a heating rate of 2℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2.

[0166] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2 h in CO at a flow rate of 20 mL / min and a heating rate of 2℃ / min to obtain the catalyst Ni / SiO2@TiO2 with a Ni mass fraction of 12%.

[0167] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0168] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0169] At 250℃, the CO2 conversion rate was 16.4% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 79.5% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 80.3% and the CH4 selectivity was 99.4%.

[0170] Example 13

[0171] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 12 g / L.

[0172] 2) Add tetrabutyl titanate to the mixture obtained in step 1), then add lanthanum nitrate to the mixture. The molar ratio of tetrabutyl titanate: fumed silica: lanthanum nitrate is 1:4.6:4. Stir for 4 hours. Add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min. The molar ratio of deionized water: tetrabutyl titanate is 3:1.

[0173] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 80°C overnight.

[0174] 4) The solid dried in step 3) is calcined at 600℃ for 4 hours at a heating rate of 2℃ / min to obtain SiO2@TiO2-La2O3. The mass ratio of SiO2:TiO2:La2O3 is 1:0.3:0.35.

[0175] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 24 hours, place it in an oven at 80°C for 6 hours, and then dry it overnight at 120°C to obtain the dried product.

[0176] 6) The dried product obtained in step 5) was calcined at 600℃ for 4h with a heating rate of 2℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2-La2O3.

[0177] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2h in H2 at a flow rate of 20mL / min with a heating rate of 2℃ / min to obtain the catalyst Ni / SiO2@TiO2-La2O3, with a Ni mass fraction of 12%.

[0178] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0179] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0180] At 250℃, the CO2 conversion rate was 56.7% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 79.8% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 75.8% and the CH4 selectivity was 99.0%.

[0181] Example 14

[0182] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 12 g / L.

[0183] 2) Add tetrabutyl titanate to the mixture obtained in step 1), then add lanthanum nitrate to the mixture. The molar ratio of tetrabutyl titanate: fumed silica: lanthanum nitrate is 1:4.6:1. Stir for 4 hours. Add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min. The molar ratio of deionized water: tetrabutyl titanate is 3:1.

[0184] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 80°C overnight.

[0185] 4) The solid dried in step 3) is calcined at 600℃ for 4 hours at a heating rate of 2℃ / min to obtain SiO2@TiO2-La2O3. The mass ratio of SiO2:TiO2:La2O3 is 1:0.3:0.05.

[0186] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 24 hours, place it in an oven at 80°C for 6 hours, and then dry it overnight at 120°C to obtain the dried product.

[0187] 6) The dried product obtained in step 5) was calcined at 600℃ for 4h with a heating rate of 2℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2-La2O3.

[0188] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2h in H2 at a flow rate of 20mL / min with a heating rate of 2℃ / min to obtain the catalyst Ni / SiO2@TiO2-La2O3, with a Ni mass fraction of 12%.

[0189] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0190] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0191] At 250℃, the CO2 conversion rate was 28.6% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 79.5% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 76.3% and the CH4 selectivity was 99.4%.

[0192] Example 15

[0193] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 12 g / L.

[0194] 2) Add tetrabutyl titanate to the mixture obtained in step 1), then add lanthanum nitrate to the mixture. The molar ratio of tetrabutyl titanate: fumed silica: lanthanum nitrate is 1:4.6:5. Stir for 4 hours. Add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min. The molar ratio of deionized water: tetrabutyl titanate is 3:1.

[0195] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 80°C overnight.

[0196] 4) Calcine the solid dried in step 3) at 600℃ for 4 hours at a heating rate of 2℃ / min to obtain SiO2@TiO2-La2O3. The mass ratio of SiO2:TiO2:La2O3 is 1:0.3:0.5.

[0197] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 24 hours, place it in an oven at 80°C for 6 hours, and then dry it overnight at 120°C to obtain the dried product.

[0198] 6) The dried product obtained in step 5) was calcined at 600℃ for 4h with a heating rate of 2℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2-La2O3.

[0199] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2h in H2 at a flow rate of 20mL / min with a heating rate of 2℃ / min to obtain the catalyst Ni / SiO2@TiO2-La2O3, with a Ni mass fraction of 12%.

[0200] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0201] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0202] At 250℃, the CO2 conversion rate was 49.2% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 78.9% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 77.6% and the CH4 selectivity was 99.3%.

[0203] Example 16

[0204] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 12 g / L.

[0205] 2) Add tetrabutyl titanate to the mixture obtained in step 1), then add cerium nitrate to the mixture. The molar ratio of tetrabutyl titanate: fumed silica: cerium nitrate is 1:4.6:4. Stir for 4 hours. Add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min. The molar ratio of deionized water: tetrabutyl titanate is 3:1.

[0206] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 80°C overnight.

[0207] 4) The solid dried in step 3) is calcined at 600℃ for 4 hours at a heating rate of 2℃ / min to obtain SiO2@TiO2-CeO2. The mass ratio of SiO2:TiO2:CeO2 is 1:0.3:0.35.

[0208] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 24 hours, place it in an oven at 80°C for 6 hours, and then dry it overnight at 120°C to obtain the dried product.

[0209] 6) The dried product obtained in step 5) was calcined at 600℃ for 4h with a heating rate of 2℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2-CeO2.

[0210] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2 h in CO at a flow rate of 20 mL / min and a heating rate of 2℃ / min to obtain the catalyst Ni / SiO2@TiO2-CeO2, with a Ni mass fraction of 12%.

[0211] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g). cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0212] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0213] At 250℃, the CO2 conversion rate was 43.4% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 80.2% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 76.5% and the CH4 selectivity was 99.2%.

[0214] Example 17

[0215] 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent. The mass concentration of silica is 12 g / L.

[0216] 2) Add tetrabutyl titanate to the mixture obtained in step 1), then add zirconium nitrate to the mixture. The molar ratio of tetrabutyl titanate: fumed silica: zirconium nitrate is 1:4.6:4. Stir for 4 hours. Add deionized water dropwise to the beaker at a feed rate of 0.2 mL / min. The molar ratio of deionized water: tetrabutyl titanate is 3:1.

[0217] 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 80°C overnight.

[0218] 4) The solid dried in step 3) is calcined at 600℃ for 4 hours at a heating rate of 2℃ / min to obtain SiO2@TiO2-ZrO2 with a mass ratio of SiO2:TiO2:ZrO2 = 1:0.3:0.25.

[0219] 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:1.2, and a nickel nitrate molar concentration of 0.77 mol / L. Add the prepared solution dropwise to the carrier obtained in step 4) by impregnation with an equal volume. After sealing and standing for 24 hours, place it in an oven at 80°C for 6 hours, and then dry it overnight at 120°C to obtain the dried product.

[0220] 6) The dried product obtained in step 5) was calcined at 600℃ for 4h with a heating rate of 2℃ / min to obtain the catalyst precursor NiO / SiO2@TiO2-ZrO2.

[0221] 7) The obtained catalyst precursor was placed in a reactor and reduced at 500℃ for 2 h in CO at a flow rate of 20 mL / min and a heating rate of 2℃ / min to obtain the catalyst Ni / SiO2@TiO2-ZrO2, with a Ni mass fraction of 12%.

[0222] 8) Under a pressure of 0.1 MPa, the contents of the reactor are increased at a volumetric space velocity of 15000 mL / (g).cat h) A CO2 methanation test was performed by introducing CO2 and hydrogen in a molar ratio of 1:4.

[0223] Under the above conditions, the catalytic performance of the CO2 hydrogenation methanation reaction is as follows:

[0224] At 250℃, the CO2 conversion rate was 43.4% and the CH4 selectivity was 100%; at 350℃, the CO2 conversion rate was 80.2% and the CH4 selectivity was 100%; at 450℃, the CO2 conversion rate was 76.5% and the CH4 selectivity was 99.2%.

[0225] All embodiments involved in this invention exhibit good catalytic performance in CO2 methanation reactions, and after long-term stability testing, the selectivity of the products remains stable without significant deactivation, demonstrating excellent stability and high application value.

[0226] The technical solutions disclosed and proposed in this invention can be implemented by those skilled in the art by appropriately modifying the conditions and routes, etc. Although the methods and preparation techniques of this invention have been described through preferred embodiments, those skilled in the art can obviously modify or recombine the methods and technical routes described herein without departing from the content, spirit, and scope of this invention to achieve the final preparation technique. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the spirit, scope, and content of this invention.

Claims

1. A Ni-based catalyst with TiO2-coated SiO2 material as support, having the composition Ni / SiO2@TiO2-MO x Ni is the active component of the catalyst, accounting for 5-20% by mass; SiO2@TiO2 is a TiO2-coated SiO2 material that serves as the catalyst support; MO x The additives added to the carrier; according to the mass ratio, SiO2:TiO2:MO x =1: a: b, where 0.15≤a≤0.50, 0<b≤0.50; MO x It can be La2O3, CeO2 or ZrO2; The method for preparing the Ni-based catalyst with TiO2-coated SiO2 material as support includes the following steps: 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent to obtain a mixture with a silica mass concentration of 10-20 g / L. 2) Add tetrabutyl titanate to the mixture obtained in step 1), and then add the corresponding nitrate to the mixture according to the molar ratio of tetrabutyl titanate: nitrate: fumed silica = 1: (0-5): (2.7-9.2), and stir for 1-6 hours; add deionized water dropwise to the beaker at a feed rate of 0.1-1 mL / min, according to the molar ratio of deionized water: tetrabutyl titanate = (2-4): 1, to obtain a solid-liquid mixture; the nitrate content is not 0; 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 60-120°C overnight; 4) The solid dried in step 3) is calcined at 500–700℃ to obtain SiO2@TiO2-MO. x ; 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:(1-3), and the concentration of nickel nitrate in the solution is 0.3-1.4 mol / L; add the prepared solution dropwise to the carrier obtained in step 4) by equal volume impregnation, seal and let stand for 12-48 h, place in an oven at 60-90 ℃ for 5-7 h, and then dry at 100-150 ℃ overnight to obtain the dried product; 6) The dried product obtained in step 5) is calcined at 500-700 °C to obtain the catalyst precursor; 7) Place the catalyst precursor obtained in step 6) into the reactor, and introduce reducing gas into the reactor to reduce the catalyst precursor; The reduction temperature was 400–700 ℃; the catalyst Ni / SiO2@TiO2-MO was obtained. x .

2. The method for preparing a Ni-based catalyst with TiO2-coated SiO2 material as a support as described in claim 1, characterized in that... Includes the following steps: 1) Add fumed silica to anhydrous ethanol and ultrasonically stir until it is completely dispersed in the ethanol solvent to obtain a mixture with a silica mass concentration of 10-20 g / L. 2) Add tetrabutyl titanate to the mixture obtained in step 1), and then add the corresponding nitrate to the mixture according to the molar ratio of tetrabutyl titanate: nitrate: fumed silica = 1: (0-5): (2.7-9.2), and stir for 1-6 hours; add deionized water dropwise to the beaker at a feed rate of 0.1-1 mL / min, according to the molar ratio of deionized water: tetrabutyl titanate = (2-4): 1, to obtain a solid-liquid mixture; the nitrate content is not 0; 3) Wash and centrifuge the mixture obtained in step 2), and dry the resulting solid in an oven at 60-120°C overnight; 4) The solid dried in step 3) is calcined at 500–700℃ to obtain SiO2@TiO2-MO. x ; 5) Prepare a solution with a molar ratio of nickel nitrate to citric acid of 1:(1-3), and the concentration of nickel nitrate in the solution is 0.3-1.4 mol / L; add the prepared solution dropwise to the carrier obtained in step 4) by equal volume impregnation, seal and let stand for 12-48 h, place in an oven at 60-90 ℃ for 5-7 h, and then dry at 100-150 ℃ overnight to obtain the dried product; 6) The dried product obtained in step 5) is calcined at 500-700 °C to obtain the catalyst precursor; 7) Place the catalyst precursor obtained in step 6) into the reactor, and introduce reducing gas into the reactor to reduce the catalyst precursor; The reduction temperature was 400–700 ℃; the catalyst Ni / SiO2@TiO2-MO was obtained. x .

3. The preparation method according to claim 2, characterized in that: Step 2) The nitrates corresponding to the auxiliary agents are lanthanum nitrate, cerium nitrate, or zirconium nitrate.

4. The preparation method according to claim 2, characterized in that: Step 4) Calcine the dried solid at 500-700℃ for 2-6 hours, with a heating rate of 1-10℃ / min.

5. The preparation method according to claim 2, characterized in that: Step 6) Calcine the dried product at 500-700℃ for 2-6 hours, with a heating rate of 1-10℃ / min.

6. The preparation method according to claim 2, characterized in that: In step 7), a reducing gas flow rate of 10–30 mL / min is introduced, and the reduction time is 1–3 h; the reduction temperature is 400–700 ℃, and the heating rate is 1–10 ℃ / min.

7. The preparation method according to claim 2, characterized in that: Step 7) The reducing gas is hydrogen, carbon monoxide, or a mixture of an inert gas and one or two of hydrogen and carbon monoxide; the volume percentage of the inert gas in the mixed gas atmosphere is 1% to 99%.

8. The Ni-based catalyst with TiO2-coated SiO2 material as a support as described in claim 1 is applied to the CO2 methanation reaction.

9. The Ni-based catalyst with TiO2-coated SiO2 material as a support as described in claim 8, applied to the CO2 methanation reaction, characterized in that, The catalyst was added to a fixed-bed reactor at a temperature of 200-500℃ and a pressure of 0.1-5 MPa, with a volume hourly space velocity (VHSV) of 15000-60000 mL / (g). cat h) Carbon dioxide and hydrogen are introduced, wherein the molar ratio of carbon dioxide to hydrogen is 1:(1-5), to obtain the target product methane.

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