Method for preparing sabatier reaction catalyst and application thereof

Abstract

The application relates to a preparation method and application of a Sabatier reaction catalyst, and the specific preparation steps are as follows: after aluminum-based salt and urea are mixed, an alcohol aluminum hydrolysis reaction, a solvothermal reaction and post-treatment are carried out to obtain an Al2O3 carrier with five-coordinated Al 3+ , then the surface of the carrier is pretreated by acid impregnation, an acid solution of a Ru-based precursor is attached to the surface of the Al2O3 carrier in an equal-volume impregnation mode, drying and calcination are carried out, and the Sabatier reaction catalyst is prepared; in the above scheme, urea is selected as an inducer, the induction capacity of urea as the inducer is improved through the synergistic effect of the solvothermal reaction, the loading capacity of the Al2O3 carrier for Ru species is improved, the performance of the prepared catalyst is further improved in combination with the pretreatment of the Al2O3 carrier and the equal-volume impregnation impregnation mode, and the prepared catalyst has excellent CO2 conversion rate and NH4 product selectivity when used as the Sabatier reaction catalyst.​​

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalyst materials, and particularly relates to a preparation method and application of a Sabatier reaction catalyst. BACKGROUND

[0002] Low-temperature Sabatier reaction (CO2 methanation reaction, i.e. the process of reacting CO2 and hydrogen to generate methane and water) can generate high-value-added products, and has the advantages of low energy consumption, and has high research value and practical effect, especially for special environments such as Mars surface with relatively more CO2 but relatively scarce resources. Considering the practical application value of low-temperature Sabatier reaction in in-situ preparation of Mars methane propellant and the like, the low-temperature Sabatier reaction has been determined by space agencies such as the US space agency as an important supporting reaction for long-term deep space exploration missions.

[0003] However, the stable molecular structure of CO2 forces the Sabatier reaction to have a high energy barrier, and thus a high-performance catalyst is more important. Among the many Sabatier reaction catalysts, Ru-based catalysts exhibit high methane selectivity and excellent stability. This is mainly due to the fact that the percentage of bonding electrons in the d orbital (4d 7 5s 1 ) of Ru element is relatively high, which facilitates the efficient dissociation of H2 at the Ru site, promotes the reaction of H with CO2 adsorbed at the Ru site in a reduced state, and generates methane in a directional manner. However, the strong adsorption performance of the Ru-based active site hinders the efficient dissociation of CO2, and thus affects the overall performance of the catalyst.

[0004] Therefore, the present application is proposed. SUMMARY

[0005] One of the purposes of the present application is to provide a Sabatier reaction catalyst preparation method to effectively improve the crystal consistency of the prepared alumina by adding a solvent thermal reaction after the alcohol aluminum hydrolysis reaction; and by selecting the inducing agent, the inducing effect of the inducing agent can be fully exerted in the solvent thermal reaction process, and by combining the pretreatment of the Al2O3 carrier and the equal-volume impregnation impregnation method, the CO2 conversion rate of the prepared Sabatier reaction catalyst is improved, and the catalytic effect is significantly improved.

[0006] The present application provides the application of the above-mentioned Sabatier reaction catalyst, which can exhibit higher CO2 conversion rate under low-temperature conditions of 300 DEG C in a Sabatier reaction system.

[0007] In order to achieve the above object, the present application provides a preparation method of a Sabatier reaction catalyst, comprising the following steps:

[0008] S1, mixing an aluminum-based salt and an inducing agent to perform an alcohol aluminum hydrolysis reaction, and then performing a solvothermal reaction and post-processing to obtain an Al2O3 carrier with five-coordinated Al 3+ ;

[0009] S2, pre-treating the Al2O3 carrier with five-coordinated Al 3+ obtained in step S1 with an acid solution;

[0010] S3, attaching a Ru-based impregnation solution to the surface of the Al2O3 carrier treated in step S2 to obtain a Sabatier reaction catalyst;

[0011] In step S1, the inducing agent is selected from one or more of urea, hexadecyl trimethyl ammonium bromide, and hexyl trimethyl ammonium bromide.

[0012] Preferably, the inducing agent is urea.

[0013] In the above scheme, after the alcohol aluminum hydrolysis reaction of the mixture of the aluminum-based salt and the inducing agent, the solvothermal reaction is performed, which can improve the crystal form consistency of the obtained Al2O3 carrier with five-coordinated Al 3+ , reduce or even eliminate the influence of Al2O3 with different crystal structures on the catalytic performance; at the same time, selecting urea, hexadecyl trimethyl ammonium bromide, and hexyl trimethyl ammonium bromide as the inducing agent can effectively improve the specific surface area and average pore size of the Al2O3 material under the premise of less influence on the surface morphology of the Al2O3 material.

[0014] Among them, urea as the preferred inducing agent can produce a synergistic effect with the solvothermal reaction process, and thus can more fully play the inducing effect of urea; it plays a good promoting role in increasing the number of active sites of the catalyst and the effective diffusion of reactants and products during the reaction process, and is conducive to the full loading of Ru species.

[0015] Through the pre-treatment of step S2, the covering of impurities on the active sites of the Al2O3 carrier and the plugging of the pores of the Al2O3 carrier are effectively avoided, which is conducive to the attachment of Ru in step S3 and improves the attachment effect of the Ru-based impregnation solution on the surface of the Al2O3 carrier; it plays a good promoting role in increasing the number of active sites of the catalyst and the effective diffusion of reactants and products during the reaction process, and is conducive to the full loading of Ru; on this basis, the catalytic effect of the obtained catalyst is improved, and the catalytic efficiency and product selectivity of the catalyst are significantly improved.

[0016] And, the Ru-based impregnation solution is attached to the surface of the Al2O3 carrier by an equal-volume impregnation method, so that the problem of uneven distribution of Ru species on the surface of the Al2O3 carrier caused by the lack or excess of the impregnation solution is avoided, and the dispersion of the Ru species is effectively improved.

[0017] Further, the step S1 is specifically:

[0018] The aluminum-based salt and the inducing agent are configured into a mixed solution, the pH of the mixed solution is adjusted to be alkaline, and then an aluminum alcoholate hydrolysis reaction is performed at a temperature of 50-120℃. After the aluminum alcoholate hydrolysis reaction is completed, a solvent thermal reaction and post-processing are performed to obtain an Al2O3 carrier with five-coordinated Al 3+ .

[0019] At this time, it should be noted that when the temperature of the aluminum alcoholate hydrolysis reaction is higher than the boiling point of the solvent, the reaction system needs to be sealed.

[0020] Preferably, the pH adjusting agent used to adjust the pH of the mixed solution is one or more of ammonia, sodium hydroxide, potassium hydroxide, sodium bicarbonate or sodium carbonate.

[0021] More preferably, the pH adjusting agent is ammonia.

[0022] Preferably, the pH of the mixed solution is adjusted to 7.5-13.5.

[0023] More preferably, the pH of the mixed solution is adjusted to 8.5-9.

[0024] The pH of the mixed solution will affect the types and properties of transition species in the preparation process of the Al2O3 material, and then affect the performance of the Al2O3 as a catalyst carrier. Since the Al2O3 precursor is an Al(OH)3-like species, the formation of this species requires the formation of an alkaline condition, but too high pH will change the types and structures of transition species, so the selection of the pH of the mixed solution as 8.5-9 meets the needs of the generation of Al(OH)3-like species, while avoiding the generation of other transition species, and ensuring the generation of five-coordinated Al 3+ .

[0025] Further, the process of the solvent thermal reaction is that after the aluminum alcoholate hydrolysis reaction is completed, the mixed solution is transferred to a sealed container and reacted at a temperature of 50-200℃.

[0026] Preferably, the temperature of the solvent thermal reaction is 150-180℃.

[0027] Preferably, the duration of the solvent thermal reaction is 0.1h-100h.

[0028] More preferably, the duration of the solvent thermal reaction is 24h.

[0029] In the above scheme, by limiting the temperature of the solvothermal reaction, the inducing effect of the inducing agent, especially urea as the template agent, is promoted; meanwhile, the solvothermal reaction needs to be carried out in a closed container, and as the reaction proceeds, the internal pressure of the closed container increases, which can further promote the inducing effect of the inducing agent, effectively improve the specific surface area and average pore size of the Al2O3 material under the premise of less influence on the surface morphology of the Al2O3 material, and play a good promoting effect on the increase of the number of active sites of the catalyst and the effective diffusion of the reactants and products during the reaction.

[0030] Further, the aluminum-based salt and the inducing agent are mixed at a temperature of 20-50°C to obtain a mixed solution, and the solvent of the mixed solution is a mixture of water and an organic solvent.

[0031] Preferably, the mixing temperature is 30°C.

[0032] Preferably, the mixed solution is prepared by stirring for 0.1h-10h after mixing.

[0033] More preferably, the stirring time is 1h.

[0034] Further, the aluminum-based salt and the inducing agent in the mixed solution are mixed at a molar ratio of 100:(1-100);

[0035] More preferably, the aluminum-based salt and the inducing agent are mixed at a molar ratio of 100:35;

[0036] Preferably, the mass ratio of the aluminum-based salt to the solvent is 1:(1-10)

[0037] Preferably, the organic solvent is selected from one or more of ethanol, propanol, butanol, isopropanol, or N,N-dimethylformamide;

[0038] Preferably, the solvent of the mixed solution is a mixture of isopropanol and water.

[0039] Preferably, the volume ratio of isopropanol to water is 1:3.

[0040] The above scheme limits the molar ratio of the aluminum-based salt and the inducing agent, which can ensure the smooth production of five-coordinated Al 3+ , while avoiding affecting the surface properties of the Al2O3 carrier. If the amount of the inducing agent is too small, the content of five-coordinated Al 3+ is too low, and the amount of the inducing agent is too large, the surface properties of the Al2O3 carrier are affected, which further affects the interaction between the Ru species and the Al2O3, and affects the performance of the catalyst.

[0041] And, the volume ratio of isopropyl alcohol to water in the solvent is limited to 1:3 in the above preferred solution, which fully considers the influence of the ratio of isopropyl alcohol to water on the performance of the Al2O3 carrier. Since the polarity of isopropyl alcohol and water is quite different, the mixing ratio of the two can directly affect the electronic properties of the surface of the Al2O3 carrier, and then affect the electronic properties of the Ru species on the surface of Al2O3, thereby improving the performance of the catalyst. In addition, the change of the ratio of isopropyl alcohol to water will affect the dissolution degree of the aluminum-based salt, and by limiting the volume ratio of isopropyl alcohol to water to 1:3, the purity of the Al2O3 material and the performance of the catalyst carrier can be directly improved.

[0042] Further, the post-treatment in step S1 includes washing, drying and calcination in sequence; the calcination temperature is 300-1000℃.

[0043] Preferably, the calcination temperature is 550℃.

[0044] Preferably, the calcination temperature is 550℃.

[0045] More preferably, the calcination temperature is 550℃.

[0046] Preferably, the calcination temperature is 550℃.

[0047] Preferably, the calcination temperature is 550℃.

[0048] Preferably, the calcination temperature is 550℃.

[0049] More preferably, the calcination temperature is 550℃.

[0050] In the above solution, if the heating rate is too fast, the Al2O3 pores will be tightened, affecting the subsequent loading of Ru species and then affecting the catalytic performance. On the contrary, if the heating rate is too slow, it will affect the preparation efficiency of the catalyst. If the calcination time is too short, the Al2O3 crystal type conversion will not be complete. If the time is too long, it will also affect the preparation efficiency of the catalyst. And the calcination temperature has a significant effect on the crystal type of the catalyst. In order to control the crystal type of the product, the best calcination temperature is between 500-600℃, and it is found in further research that 550℃ is the optimal calcination temperature.

[0051] Further, the cleaning agent used in step S1 is a mixture of water and an organic solvent, wherein the organic solvent is selected from one or more of ethanol, propanol, butanol, isopropyl alcohol or N,N-dimethylformamide.

[0052] The organic solvent is preferably ethanol, and the cleaning agent is preferably a mixture of ethanol and water with a volume ratio of 1:3.

[0053] Furthermore, the drying temperature in step S1 is 50-200℃, and the drying time is 0.1h-100h.

[0054] Preferably, the drying temperature in step S1 is 120°C and the drying time is 24 hours.

[0055] Furthermore, step S2 specifically involves:

[0056] The Al with five coordinations obtained in step S1 3+ The Al2O3 support was impregnated in acid, then washed, dried and calcined to obtain pretreated Al with five coordination groups. 3+ Al2O3 carrier.

[0057] The above method achieves pretreatment of Al2O3 support through acid impregnation and subsequent cleaning, drying and calcination, effectively avoiding the covering of active sites on the surface of Al2O3 support by impurities and the blockage of the pores of Al2O3 support, and improving the adhesion effect of Ru-based impregnation solution on the surface of Al2O3 support.

[0058] Preferably, the acid used for impregnation is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid.

[0059] Preferably, the acid used for impregnation is a hydrochloric acid solution with a mass concentration of 1-36%.

[0060] More preferably, the acid used for impregnation is a hydrochloric acid solution with a mass concentration of 20-32%.

[0061] More preferably, the acid used for impregnation is a 27% hydrochloric acid solution.

[0062] Furthermore, the drying temperature in step S2 is 30-150℃, and the drying time is 1h-24h.

[0063] Preferably, the drying temperature in step S2 is 120°C and the drying time is 2 hours.

[0064] Furthermore, the calcination temperature in step S2 is 20-1000℃, preferably 400℃.

[0065] Furthermore, the roasting time in step S2 is 1h-24h; preferably 2h.

[0066] Furthermore, step S3 specifically includes:

[0067] Ru-based impregnation solution was dropped onto the surface of the Al2O3 support pretreated in step S2 until no liquid precipitation occurred. Then, the catalyst was obtained by heat preservation, drying, and calcination.

[0068] Preferably, the temperature is 20-90℃.

[0069] More preferably, the temperature is 30℃.

[0070] In the above scheme, the Ru-based impregnating solution is attached to the surface of the Al2O3 carrier by equal-volume impregnation, avoiding the problem of uneven distribution of Ru on the surface of the Al2O3 carrier caused by insufficient or excessive impregnating solution, and effectively improving the dispersion of Ru.

[0071] The Al2O3 carrier loaded with the Ru-based impregnating solution is treated by vacuum drying at 20-90℃, effectively removing free water while avoiding the influence of Ru-based precursor aggregation and growth caused by the oxygen-rich environment and high temperature on the performance of the catalyst when the interaction between Ru and the Al2O3 carrier is weak.

[0072] Further, the holding time in step S3 is 0.1h-10h, preferably 2h.

[0073] Further, the Ru-based impregnating solution is an acid solution of a Ru-based precursor.

[0074] Further, the preparation process of the Ru-based impregnating solution is as follows: dissolving the Ru-based precursor in an acid solution, sealing and stirring until no obvious precipitate is precipitated, and then stirring in the open air to obtain the Ru-based impregnating solution.

[0075] Preferably, the Ru-based precursor is selected from one or more of ruthenium chloride, ruthenium acetate, ruthenium acetylacetone, ruthenium sulfate or ruthenium oxide; and the acid in the Ru-based impregnating solution is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid.

[0076] Preferably, the Ru-based precursor is ruthenium chloride, and the acid in the Ru-based impregnating solution is a hydrochloric acid solution with a mass concentration of 1-36%.

[0077] More preferably, the acid in the Ru-based impregnating solution is a hydrochloric acid solution with a mass concentration of 20-32%.

[0078] More preferably, the acid in the Ru-based impregnating solution is a hydrochloric acid solution with a mass concentration of 27%.

[0079] The above scheme effectively improves the uniformity of Ru ions in the Ru-based impregnating solution by adding an acid solution to the Ru-based impregnating solution, avoids the deposition of Ru ions in the Ru-based impregnating solution caused by long-term storage, improves the uniformity of the distribution of the Ru-based impregnating solution on the surface of the Al2O3 carrier and the dispersion of Ru, and additionally, the more H + ions in the acid solution enhance the interaction between Ru and the Al2O3 carrier, effectively enhancing the regulation effect of the Al2O3 carrier on the electronic properties of the Ru-based active site while improving the dispersion of Ru.

[0080] Further, in step S3, the calcination temperature ranges from 100 to 1000℃; the temperature rising rate of the calcination temperature ranges from 0.1 to 50℃ / min;

[0081] Preferably, the calcination temperature is 400℃; the temperature rising rate is 10℃ / min.

[0082] Preferably, the calcination time ranges from 0.1 to 10h.

[0083] More preferably, the calcination time is 2h.

[0084] Further, the drying process of step S3 is specifically that the mixture containing the Ru-based impregnation solution and the pretreated Al2O3 carrier is dried under vacuum at a temperature of 30-120℃.

[0085] The above scheme dries the mixture formed after the Ru-based impregnation solution adheres to the surface of the Al2O3 carrier by the way of low-temperature vacuum drying, which effectively removes free water while avoiding the influence of the aggregation and growth of Ru species on the catalyst performance caused by the rich oxygen environment and high temperature when the interaction between the Ru species and the Al2O3 carrier is weak.

[0086] Preferably, the vacuum drying temperature is 50℃.

[0087] Preferably, the drying time ranges from 0.1 to 10h.

[0088] More preferably, the drying time is 5h.

[0089] Further, in step S3, the reduction process is specifically that:

[0090] The Ru / Al2O3 catalyst after the end of calcination is placed in an atmosphere of a reducing gas, and then heated to a reduction temperature of 100-1000℃ at a preset temperature rising rate for reduction;

[0091] The reducing gas is a mixed gas of H2 and Ar.

[0092] Preferably, the reducing gas is a mixed gas of H2 and Ar mixed at a volume ratio of 1:(1-100).

[0093] More preferably, the volume ratio of H2 to Ar is 1:3.

[0094] Preferably, the reduction temperature is 300℃.

[0095] Preferably, the reduction time ranges from 0.1h to 10h.

[0096] More preferably, the reduction time is 5h.

[0097] Preferably, the preset temperature rising rate ranges from 0.1 to 50℃ / min.

[0098] More preferably, the preset temperature rising rate is 10℃ / min.

[0099] Further, the Ru / Al2O3 catalyst after the end of the calcination is placed in the atmosphere of the reducing gas at a temperature of 10-60℃.

[0100] Preferably, the Ru / Al2O3 catalyst after the end of the calcination is placed in the atmosphere of the reducing gas at a temperature of 30℃.

[0101] Preferably, the reducing temperature is 300℃.

[0102] Preferably, the reducing time is 0.1-10h.

[0103] More preferably, the reducing time is 5h.

[0104] Preferably, the preset temperature rising rate is 0.1h-50℃ / min.

[0105] More preferably, the preset temperature rising rate is 10℃ / min.

[0106] It should be noted that the above reduction step can be performed after the end of the calcination or before the use of the catalyst, when the reduction step is performed after the end of the calcination, the aging treatment is further needed after the end of the reduction, and the specific process of the aging is as follows:

[0107] The reduced Ru / Al2O3 catalyst is placed in the aging atmosphere and aged at an aging temperature of 10-100℃.

[0108] More preferably, the aging temperature is 30℃, and the aging time is 0.1h-10h.

[0109] The second aspect of the present application provides an application of the above-mentioned Sabatier reaction catalyst, which is used as the catalyst of the Sabatier reaction, and the preferable catalytic temperature of the Sabatier reaction catalyst is 275-300℃, and the catalytic performance at 300℃ is better, and the conversion rate of CO2 is higher than 60%.

[0110] The beneficial effects of the present application are as follows:

[0111] 1. The Sabatier reaction catalyst prepared by the method of the present application has the five-coordinated Al 3+The strong interaction between the site and the Ru species realizes the regulation of the electronic property of the Ru-based active site, and through the synergy between the selection of the inducing agent and the solvothermal reaction, and the pretreatment of the Al2O3 carrier, the Al2O3 carrier has a high specific surface area and a small particle size and a relatively concentrated particle size distribution, the number of Ru-based active sites is increased, and through the isometric impregnation method, the Ru species is fully attached to the surface of the carrier, and the situations of insufficient impregnation or excessive impregnation do not occur, and then the catalytic performance of the catalyst is improved.

[0112] 2、 The preparation method provided by the application solves the problem that the regulation degree of the electronic property of the Ru-based active site by the Al2O3 carrier is not easy to control, the regulation degree of the electronic property of the Ru-based active site is controlled by adjusting the amount of the inducing agent, and then the CO2 conversion rate and the CH4 selectivity are regulated; meanwhile, through the synergy between the solvothermal reaction and the inducing agent, the inducing ability of the inducing agent is improved, the loading capacity of the Ru species is improved, the contact degree of the reactants with the catalyst is improved, and then the catalytic performance is improved.

[0113] 3、 The application adds an acid solution to the Ru-based impregnation liquid, effectively improves the uniformity of Ru ions in the Ru-based impregnation liquid, avoids the deposition of Ru ions in the Ru-based impregnation liquid caused by long-term storage, improves the uniformity of the Ru-based impregnation liquid on the surface of the Al2O3 carrier and the dispersion degree of the Ru species, and the H + + of the acid solution enhances the interaction between the Ru species and the Al2O3 carrier, effectively enhances the regulation effect of the Al2O3 carrier on the electronic property of the Ru-based active site while improving the dispersion degree of the Ru species.

[0114] 4、 The method solves the problem that the regulation degree of the electronic property of the Ru-based active site by the Al2O3 carrier is not easy to control, the performance of the catalyst is poor, and the performance stability is insufficient, effectively improves the regulation degree of the electronic property of the Ru-based active site, improves the catalytic performance and the performance stability of the catalyst, and the method also has the advantages of simple operation and easy large-scale preparation. BRIEF DESCRIPTION OF DRAWINGS

[0115] Figure 1 Figure 4 is a performance stability test diagram of the Sabatier reaction catalyst prepared by the method of the first embodiment of the application.

[0116] Figure 2 Figure 5 is an XRD diagram of the Al2O3 carrier prepared by different embodiments and comparative examples of the application.

[0117] Figure 3 Figure 6 is a TEM diagram of the Al2O3 carrier prepared by different embodiments and comparative examples of the application. 27Al NMR chart.

[0118] Figure 4 Specific surface area test chart of Sabatier reaction catalyst prepared for different embodiments and comparative examples of the present application.

[0119] Figure 5 Transmission electron microscope chart of Sabatier reaction catalyst prepared for different embodiments and comparative examples of the present application.

[0120] Figure 6 Ru species X-ray photoelectron spectroscopy chart of Sabatier reaction catalyst surface prepared for different embodiments and comparative examples of the present application.

[0121] Figure 7 H2 temperature programmed reduction chart of Ru species of Sabatier reaction catalyst surface prepared for different embodiments and comparative examples of the present application.

[0122] Figure 8 CO2 conversion rate and CH4 selectivity test chart of Sabatier reaction catalyst prepared for different embodiments and comparative examples of the present application at different reaction temperatures. DETAILED DESCRIPTION

[0123] The exemplary embodiments of the present application will be described in more detail below with reference to the accompanying drawings, and those skilled in the art can understand that the following embodiments are only used to explain the technical principles of the present application, and are not intended to limit the protection scope of the present application.

[0124] It should be noted that:

[0125] In order to more accurately test the catalyst performance, the catalyst sample powder is pressed into tablets, granulated, sieved, and then prepared into 40-60 mesh catalyst particles. 2g of catalyst is accurately weighed, and the volume of the catalyst is measured with a measuring cylinder. Then, the catalyst particles are loaded into a stainless steel reaction tube with an inner diameter of 2cm, and fixed with high-temperature resistant quartz wool. The stainless steel reaction tube loaded with the catalyst is placed in a heating furnace, and the reaction gas circuit and the electric circuit are connected.

[0126] When detecting the CO2 conversion rate and CH4 selectivity of the catalyst at different temperatures, first, the reaction device is purged under N2 atmosphere for 1 hour, and the N2 flow rate is 10mL·min -1 Then, switch to a reaction mixed gas containing CO2, H2 and N2, wherein the molar ratio of CO2 to H2 is 1:4. N2 is used as an internal standard for the reaction gas, and the N2 flow rate is 100ml / min. According to the amount of catalyst, the flow rate of the mixed reaction gas is adjusted to 9000ml·g -1 ·h -1The reaction temperature was controlled at 50-500℃. Each temperature point was kept for 2h, and the reactor outlet was connected to gas chromatography for online collection and analysis of products.

[0127] In the detection of catalyst performance stability, the reaction device was first purged for 1h under the N2 atmosphere of 10mL·min -1 Then, the reaction mixed gas containing CO2, H2 and N2 was switched, wherein the molar ratio of CO2 to H2 was 1:4, the reaction gas used N2 as an internal standard, the flow rate of N2 was 100ml·min -1 According to the amount of catalyst, the flow rate of mixed reaction gas was adjusted to 3000ml·g -1 ·h -1 The reaction temperature was stabilized at 300℃. The sample was taken every 2h, and the reactor outlet was connected to gas chromatography for online collection and analysis of products.

[0128] The reaction products were detected online by gas chromatography (Shimadzu, 2014C), and the peak area and content of each component at the outlet were obtained by using hydrogen flame ionization detection (FID) and thermal conductivity detector (TCD). The tail gas in the chromatographic sampling tube was separated by an activated carbon column, analyzed by thermal conductivity detector TCD, and the flame ionization detector FID was used to detect whether there were alkanes, alkenes or aromatic hydrocarbons and other products in the product. The calculation formulas of CO2 conversion (C CO2 ) and CH4 selectivity (S CH4 ) are as follows:

[0129]

[0130]

[0131] Wherein, CO2(in) and CO2(out) represent the CO2 in the inlet gas before reaction and the outlet gas after reaction calculated based on the internal standard N2, and CH4(out) represents the outlet gas of methane after reaction calculated based on the internal standard N2.

[0132] The test results of Examples 1 to 4 and Comparative Example 1 are shown in Table 1. Figures 1 to 8

[0133] The application will be further described in detail in combination with the drawings and specific examples:

[0134] Example 1

[0135] ​A mixture solution A was prepared by adding aluminum isopropoxide and urea in a molar ratio of 10:3.5 into a mixed solvent of isopropyl alcohol and ultrapure water in a volume ratio of 1:3. The mass ratio of aluminum isopropoxide to the mixed solvent was 1:4. After the mixture solution A was stirred at room temperature for 0.5 hours, an ammonia solution was added dropwise to adjust the pH value of the mixture solution to 8.5. After the mixture solution was continuously stirred for 1 hour, a mixture solution B was formed. The mixture solution B was placed in a thermostatic water bath at 70°C and continuously stirred with the aid of a mechanical stirrer for 1 hour to form a mixture solution C.

[0136] The mixture solution C was transferred into the liner of a solvothermal reactor. After the reactor was sealed, the solvothermal reactor containing the solution C was transferred into a blast drying oven at 160°C and kept for 24 hours. After the solvothermal reaction was completed, the reactor was taken out of the blast drying oven, and the temperature was reduced to room temperature. The white powder in the reactor was taken out and washed with a mixed solvent of ultrapure water and ethanol in a volume ratio of 3:1 until the powder was neutral. Then, the powder was placed in a blast drying oven at 120°C and dried for 24 hours. After the drying was completed, the white powder was placed in a muffle furnace, and the muffle furnace was raised to 550°C at a rate of 10°C / min. The white powder was calcined at 550°C for 5 hours to obtain an Al2O3 support with pentacoordinate Al 3+ .

[0137] The Al2O3 support powder with pentacoordinate Al 3+ was added into a hydrochloric acid solution with a mass concentration of 27% to form a mixture solution D. The mass ratio of the Al2O3 powder to the hydrochloric acid solution was 1:2. After the mixture solution D was stirred at room temperature for 1 hour, the powder was washed with a mixed solvent of ultrapure water and ethanol in a volume ratio of 3:1 until the powder was neutral. The washing was repeated for 3 times. After the washing was completed, the Al2O3 powder was placed in a blast drying oven and dried at 120°C for 12 hours. Then, the powder was placed in a muffle furnace and heated to 400°C at a rate of 10°C / min. The powder was calcined at 400°C for 2 hours to obtain a pretreated Al2O3 support with pentacoordinate Al 3+ .

[0138] RuCl3 powder was placed in a hydrochloric acid solution with a mass concentration of 27% to form a mixture solution E. The mixture solution E was stirred at 50°C for 2 hours. After no obvious precipitate was observed in the solution, the solution was continuously stirred at 70°C for 5 hours. After the solution was cooled to room temperature, a Ru-based impregnation solution was obtained.

[0139] The Ru-based impregnation solution was added dropwise to the pretreated Al2O3 support with pentacoordinate Al 3+The Al2O3 support was dried until no liquid precipitated. After the addition was complete, the mixture was aged at room temperature for 5 hours, then dried in a vacuum drying oven at 50°C for 5 hours. After drying, it was placed in a muffle furnace and calcined at 400°C for 2 hours at a rate of 10°C / min. After calcination, it was placed in a tubular reduction furnace and purged with a mixture of H2 and Ar at a volume ratio of 1:9 at 30°C for 2 hours. Then, the temperature was increased to 300°C at a rate of 10°C / min, and reduced with a mixture of H2 and Ar at a volume ratio of 1:9 at 300°C for 5 hours. After reduction, the furnace was allowed to cool to room temperature, and the mixture was aged at room temperature for 10 hours using nitrogen and air at a volume ratio of 4:1. The Sabatier reaction catalyst was then obtained.

[0140] Testing revealed that the Sabatier reaction catalyst prepared in Example 1 exhibited characteristic peaks of the (311), (400), and (440) crystal planes of γ-Al₂O₃ at positions of 37.5°, 46.5°, and 67.5°; the Ru on the catalyst surface... 0 Species and Ru 4+ The characteristic peaks of the species are at 461.8 eV and 464.3 eV, respectively; the reduction temperature of the Ru species is 194.1 °C; the catalyst achieves CO2 conversion and CH4 selectivity of 90.7% and 91.5% respectively in the low-temperature region (300 °C), and the catalytic performance does not significantly decrease within a 100-hour reaction time. Figure 1 As can be seen intuitively, although the CO2 conversion rate and CH4 selectivity fluctuate within 100 hours, they are generally above 90% and basically stable, which fully demonstrates that the catalyst prepared in this example has excellent stability.

[0141] from Figure 3 It is evident from the image that the catalyst prepared in this embodiment contains five-coordinated Al. 3+ And five-coordinate Al 3+ The proportion reached 28.1%.

[0142] from Figure 5 As can be seen from the above, the Ru attached to the catalyst prepared in this embodiment has an excellent particle size distribution, with the particle size basically exhibiting a normal distribution and an average particle size of about 3.7.

[0143] from Figure 8As can be seen from the above table, the CO2 conversion rate of the catalyst prepared in the embodiment increases with the increase of the reaction temperature, and reaches more than 90% at 300℃, and the increase of the selectivity is significantly reduced with the further increase of the reaction temperature; it can also be seen that the CH4 selectivity of the catalyst prepared in the embodiment remains basically unchanged before 300℃, and is obviously reduced after 300℃; it is indicated that the catalyst prepared in the embodiment has excellent CO2 conversion rate at 300℃, and also has high CH4 selectivity, and has excellent catalytic performance at low temperature.

[0144] Example 2

[0145] aluminum isopropoxide and urea in a molar ratio of 10:5 were added into a mixed solvent of ethanol and ultrapure water in a volume ratio of 1:3 to form a mixed solution A, wherein the mass ratio of aluminum isopropoxide to the mixed solvent was 1:4; after the mixed solution A was stirred at room temperature for 0.5 hours, an ammonia solution was added dropwise, the pH value of the mixed solution was adjusted to 9, and the stirring was continued for 1 hour to form a mixed solution B; the mixed solution B was placed in a constant temperature water bath at 70℃ and continuously stirred for 1 hour with the aid of a mechanical stirrer to form a mixed solution C.

[0146] The mixed solution C was transferred into the inner liner of a solvothermal reactor, and after the reactor was sealed, the solvothermal reactor containing the solution C was transferred into a blast drying oven at 180℃ and kept for 24 hours; after the solvothermal reaction was completed, the reactor was taken out of the blast drying oven, and after the temperature was reduced to room temperature, the white powder in the reactor was taken out and washed to neutral with a mixed solvent of ultrapure water and ethanol in a volume ratio of 3:1, and then the powder was placed in a blast drying oven at 120℃ and dried for 24 hours; after the drying was completed, the white powder was placed in a muffle furnace, the muffle furnace was raised to 600℃ at a rate of 10℃ / min, and the powder was calcined at 600℃ for 5 hours to obtain an Al2O3 carrier with five-coordinated Al 3+ .

[0147] The Al2O3 carrier powder with five-coordinated Al 3+ was added into a hydrochloric acid solution with a mass concentration of 27% to form a mixed solution D, wherein the mass ratio of the Al2O3 powder to the hydrochloric acid solution was 1:2; after the mixed solution D was stirred at room temperature for 1 hour, the powder was washed to neutral with a mixed solvent of ultrapure water and ethanol in a volume ratio of 3:1, and the step was repeated 4 times; after the washing was completed, the Al2O3 powder was placed in a blast drying oven, dried in the blast drying oven at 110℃ for 10 hours, and then placed in a muffle furnace and heated to 450℃ at a rate of 10℃ / min for calcination for 2 hours; after the calcination was completed, a pretreated Al2O3 carrier with five-coordinated Al 3+ was obtained.

[0148] The RuCl3 powder was placed in a 27% hydrochloric acid solution to form a mixed solution E. The mixed solution E was stirred at 60°C for 2 hours. When no obvious precipitate was formed in the solution, the stirring was continued at 60°C for 5 hours. The solution was cooled to room temperature to obtain a Ru-based impregnation solution.

[0149] The Ru-based impregnation solution was added dropwise to the pretreated Al2O3 carrier with five-coordinated Al 3+ . No liquid was precipitated after the addition was completed. The solution was aged at room temperature for 10 hours. Then, the solution was dried in a vacuum drying oven at 50°C for 3 hours. After the drying was completed, the solution was placed in a muffle furnace and heated to 420°C at a rate of 10°C / min and calcined for 2 hours. After the calcination was completed, the solution was placed in a tube furnace and passed through a mixed gas of H2 and Ar at a volume ratio of 1:9 at 30°C for 2 hours. Then, the solution was heated to 250°C at a rate of 10°C / min and reduced with the mixed gas of H2 and Ar at a volume ratio of 1:9 at 250°C for 5 hours. After the reduction was completed, the solution was aged with a mixed gas of nitrogen and air at a volume ratio of 4:1 at room temperature for 5 hours. Thus, a Sabatier reaction catalyst was obtained.

[0150] The Sabatier reaction catalyst prepared in Example 2 was tested. The catalyst exhibited characteristic peaks of (311) crystal plane, (400) crystal plane and (440) crystal plane of γ-Al2O3 at positions of 37.5°, 46.5° and 67.5°, respectively. The characteristic peaks of Ru 0 species and Ru 4+ species on the surface of the catalyst were at 461.8 eV and 464.1 eV, respectively. The reduction temperature of the Ru species was 183.7°C.

[0151] It can be seen from Figure 3 that the catalyst prepared in this example contains five-coordinated Al 3+ , and the proportion of the five-coordinated Al 3+ is 40.7%,

[0152] It can be seen from Figure 5 that the particle size distribution of the Ru attached to the catalyst prepared in this example is excellent, and the particle size is basically normally distributed, with an average particle size of about 3.2.

[0153] It can be seen from Figure 8As can be seen from the table, the CO2 conversion rate of the catalyst prepared in the embodiment increases with the increase of the reaction temperature, and reaches more than 90% at 300℃, and the increase amplitude of the selectivity decreases significantly with the further increase of the reaction temperature; it can also be seen that the CH4 selectivity of the catalyst prepared in the embodiment remains basically unchanged before 275℃, slightly decreases at 300℃, and the decrease amplitude gradually increases with the increase of the temperature; in combination of the CO2 conversion rate and the CH4 selectivity of the catalyst, it can be seen that the catalyst prepared in the embodiment has excellent catalytic performance in the range of 275-300℃, and has excellent catalytic performance at low temperature.

[0154] Example 3

[0155] Aluminum isopropyl alcohol and urea in a molar ratio of 10:2 were added into a mixed solvent of isopropyl alcohol and ultrapure water in a volume ratio of 1:4 to form a mixed solution A. The mass ratio of aluminum isopropyl alcohol to the mixed solvent was 1:3. After the mixed solution A was stirred at room temperature for 0.5 hours, an ammonia solution was added dropwise, the pH value of the mixed solution was adjusted to 8.7, and the stirring was continued for 1 hour to form a mixed solution B. The mixed solution B was placed in a constant temperature water bath at 80℃, and was continuously stirred for 1 hour under the assistance of a mechanical stirrer to form a mixed solution C.

[0156] The mixed solution C was transferred into the lining of a solvothermal reactor, and after the reactor was sealed, the solvothermal reactor containing the solution C was transferred into a blast drying oven at 170℃ and was kept for 18 hours. After the solvothermal reaction was completed, the reactor was taken out of the blast drying oven, and after the temperature decreased to room temperature, the white powder in the reactor was taken out, and was washed to neutral with a mixed solvent of ultrapure water and ethanol in a volume ratio of 3:1. Then, the powder was placed in a blast drying oven at 120℃ and was dried for 24 hours. After the drying was completed, the white powder was placed in a muffle furnace, the muffle furnace was raised to 500℃ at a rate of 10℃ / min, and was calcined at 500℃ for 5 hours to obtain an Al2O3 carrier with five-coordinated Al 3+ ;

[0157] The Al2O3 carrier powder with five-coordinated Al 3+ was added into a hydrochloric acid solution with a mass concentration of 27% to form a mixed solution D, wherein the mass ratio of the Al2O3 powder to the hydrochloric acid solution was 1:2. After the mixed solution D was stirred at room temperature for 1 hour, the powder was washed to neutral with a mixed solvent of ultrapure water and ethanol in a volume ratio of 3:1. After the washing was repeated for 4 times, the Al2O3 powder after the washing was placed in a blast drying oven, was dried at 90℃ for 10 hours, and then was placed in a muffle furnace and was calcined at a temperature rising rate of 10℃ / min to 500℃ for 2 hours. After the calcination was completed, a pretreated Al2O3 carrier with five-coordinated Al 3+ was obtained.

[0158] The RuCl3 powder was placed in a 27% mass concentration hydrochloric acid solution to form a mixed solution E. The mixed solution E was stirred at 70°C for 2 hours in a sealed state. When no obvious precipitate was observed in the solution, the stirring was continued at 50°C for 5 hours in an open state. When the solution was cooled to room temperature, a Ru-based impregnation solution was obtained.

[0159] The Ru-based impregnation solution was added dropwise to the pretreated Al2O3 carrier with five-coordinated Al 3+ . When no liquid was precipitated, the dropwise addition was stopped. After aging at room temperature for 12 hours, the solution was dried in a vacuum drying oven at 50°C for 5 hours. After drying, the solution was placed in a muffle furnace and heated to 400°C at a rate of 10°C / min and calcined for 2 hours. After calcination, the solution was placed in a tube furnace and passed through a mixed gas of H2 and Ar with a volume ratio of 1:9 at a temperature of 30°C for 2 hours. Then the temperature was increased to 270°C at a rate of 10°C / min and the solution was reduced with the mixed gas of H2 and Ar with a volume ratio of 1:9 at 270°C for 3 hours. After reduction, the solution was aged at room temperature for 12 hours with a mixed gas of nitrogen and air with a volume ratio of 4:1. A Sabatier reaction Ru-based catalyst was obtained.

[0160] Tests showed that the Sabatier reaction catalyst prepared in Example 3 exhibited characteristic peaks of the (311) crystal plane, the (400) crystal plane and the (440) crystal plane of γ-Al2O3 at positions of 37.5°, 46.5° and 67.5°, respectively. The characteristic peaks of the Ru 0 species and the Ru 4+ species on the surface of the catalyst were at 461.8 eV and 464.5 eV, respectively. The reduction temperature of the Ru species was 203.8°C.

[0161] It can be clearly seen from Figure 3 that the catalyst prepared in this example contains five-coordinated Al 3+ , and the proportion of the five-coordinated Al 3+ reaches 12.9%,

[0162] It can be seen from Figure 5 that the particle size distribution of the attached Ru in the catalyst prepared in this example is excellent, and the particle size is basically normally distributed with an average particle size of about 4.5.

[0163] It can be seen from Figure 8It can be seen that the CO2 conversion rate of the catalyst prepared in the embodiment increases with the increase of the reaction temperature, and reaches more than 90% at 350°C, and the CO2 conversion rate is also higher than 70% at 300°C, and the increase amplitude of the selectivity is significantly reduced with the further increase of the reaction temperature; it can also be seen that the CH4 selectivity of the catalyst prepared in the embodiment is relatively high, and is higher than 90% and basically unchanged in the range of 200-390°C; in combination of the CO2 conversion rate and the CH4 selectivity of the catalyst, it can be seen that the catalyst prepared in the embodiment has excellent catalytic performance in the range of 300-400°C, and can meet the demand of low-temperature catalysis, and has excellent catalytic performance at low temperature.

[0164] Example 4

[0165] Aluminum nitrate and urea in a molar ratio of 10:3.5 were added into a mixed solvent of isopropyl alcohol and ultrapure water in a volume ratio of 1:3 to form a mixed solution A. The mass ratio of aluminum nitrate to the mixed solvent was 1:4. After the mixed solution A was stirred at room temperature for 0.5 hours, an ammonia solution was added dropwise, the pH value of the mixed solution was adjusted to 9, and the stirring was continued for 1 hour to form a mixed solution B. The mixed solution B was placed in a constant temperature water bath at 60°C, and was continuously stirred for 1 hour under the assistance of a mechanical stirrer to form a mixed solution C.

[0166] The mixed solution C was transferred into the lining of a solvothermal reaction kettle, and after the reaction kettle was sealed, the solvothermal reaction kettle containing the solution C was transferred into a blast drying oven at 150°C and was kept for 24 hours. After the solvothermal reaction was completed, the reaction kettle was taken out of the blast drying oven, and after the temperature was reduced to room temperature, the white powder in the reaction kettle was taken out, and after being washed to neutral with a mixed solvent of ultrapure water and ethanol in a volume ratio of 3:1, the powder was placed in a blast drying oven at 120°C and was dried for 24 hours. After the drying was completed, the white powder was placed in a muffle furnace, the muffle furnace was raised to 500°C at a rate of 10°C / min, and was calcined at 500°C for 5 hours to obtain an Al2O3 carrier with five-coordinated Al 3+ .

[0167] The Al2O3 carrier powder with five-coordinated Al 3+ was added into a hydrochloric acid solution with a mass concentration of 27% to form a mixed solution D, and the mass ratio of the Al2O3 powder to the hydrochloric acid solution was 1:3. After the mixed solution D was stirred at room temperature for 1 hour, the powder was washed to neutral with a mixed solvent of ultrapure water and ethanol in a volume ratio of 3:1, and the step was repeated for 3 times. After the washing was completed, the Al2O3 powder was placed in a blast drying oven, was dried in the blast drying oven at 120°C for 12 hours, and was then placed in a muffle furnace and was calcined at a rate of 10°C / min to 400°C for 2 hours. After the calcination was completed, a pretreated Al2O3 carrier with five-coordinated Al3+ Al2O3 carrier.

[0168] RuCl3 powder was placed in a 27% hydrochloric acid solution to form a mixed solution E. The mixed solution E was sealed and stirred at 50°C for 2 hours. When no obvious precipitate was formed in the solution, it was stirred open at 60°C for 7 hours. When the solution cooled to room temperature, Ru-based impregnation solution was obtained.

[0169] Ru-based impregnation solution was dropwise added to pretreated Al with five coordination groups. 3+ The Al2O3 support was dried until no liquid precipitated. After the addition was complete, the mixture was aged at room temperature for 10 hours, then dried in a vacuum drying oven at 50°C for 5 hours. After drying, it was placed in a muffle furnace and calcined at 420°C for 2 hours at a rate of 10°C / min. After calcination, it was placed in a tubular reduction furnace and purged with a 1:9 mixture of H2 and Ar at 30°C for 2 hours. Then, the temperature was increased to 290°C at a rate of 10°C / min, and reduced with a 1:9 mixture of H2 and Ar at 290°C for 5 hours. After reduction, the furnace was allowed to cool to room temperature, and the mixture was aged at room temperature for 12 hours with a 4:1 mixture of nitrogen and air. The Sabatier reaction catalyst was then obtained.

[0170] Testing revealed that the Sabatier reaction catalyst prepared in Example 4 exhibited characteristic peaks of the (311), (400), and (440) crystal planes of γ-Al₂O₃ at positions of 37.5°, 46.5°, and 67.5°; the Ru on the catalyst surface... 0 Species and Ru 4+ The characteristic peaks of the species are at 461.8 eV and 464.4 eV, respectively; the reduction temperature of the Ru species is 208.8 °C.

[0171] from Figure 3 It is evident from the image that the catalyst prepared in this embodiment contains five-coordinated Al. 3+ And five-coordinate Al 3+ The proportion reached 15.3%.

[0172] from Figure 5 As can be seen from the above, the Ru attached to the catalyst prepared in this embodiment has an excellent particle size distribution, with the particle size basically exhibiting a normal distribution and an average particle size of about 3.7.

[0173] from Figure 8As can be seen, the CO2 conversion rate of the catalyst prepared in the embodiment increases with the increase of the reaction temperature, and reaches more than 60% at 300°C, and continues to increase in the range of 300-400°C and stabilizes at about 80%; it can also be seen that the CH4 selectivity of the catalyst prepared in the embodiment is high as a whole, and is higher than 90% before 325°C, and gradually decreases after the temperature exceeds 325°C; in combination of the CO2 conversion rate and the CH4 selectivity of the catalyst, it can be seen that the catalyst prepared in the embodiment has excellent catalytic performance at 300°C, and can meet the demand of low-temperature catalysis.

[0174] Comparative Example 1

[0175] Aluminum isopropoxide was added into a mixed solvent of isopropyl alcohol and ultrapure water with a volume ratio of 1:3 to form a mixed solution A. The mass ratio of aluminum isopropoxide to the mixed solvent was 1:3. After the mixed solution A was stirred at room temperature for 0.5 hours, an ammonia solution was added dropwise, the pH value of the mixed solution was adjusted to 8.5, and the stirring was continued for 1 hour to form a mixed solution B. The mixed solution B was placed in a constant-temperature water bath at 70°C, and was continuously stirred for 1 hour under the assistance of a mechanical stirrer to form a mixed solution C.

[0176] The mixed solution C was transferred into the inner liner of a solvothermal reaction kettle, the reaction kettle was sealed, and the solvothermal reaction kettle containing the solution C was transferred into a blast drying oven at 160°C and was kept for 24 hours. After the solvothermal reaction was completed, the reaction kettle was taken out of the blast drying oven, and the temperature was reduced to room temperature. The white powder in the reaction kettle was taken out, and was washed to neutral with a mixed solvent of ultrapure water and ethanol with a volume ratio of 3:1. Then, the powder was placed in a blast drying oven at 120°C and was dried for 24 hours. After the drying was completed, the white powder was placed in a muffle furnace, the muffle furnace was raised to 550°C at a rate of 10°C / min, and was calcined at 550°C for 5 hours. Thus, an Al2O3 carrier was obtained.

[0177] The Al2O3 carrier powder was added into a hydrochloric acid solution with a mass concentration of 27% to form a mixed solution D, and the mass ratio of the Al2O3 powder to the hydrochloric acid solution was 1:4. After the mixed solution D was stirred at room temperature for 1 hour, the powder was washed to neutral with a mixed solvent of ultrapure water and ethanol with a volume ratio of 3:1. The step was repeated for 3 times. After the washing was completed, the Al2O3 powder was placed in a blast drying oven, was dried in the blast drying oven at 120°C for 12 hours, was placed in a muffle furnace, and was calcined at a temperature rising rate of 10°C / min to 500°C for 2 hours. Thus, a pretreated Al2O3 carrier was obtained.

[0178] RuCl3 powder was placed in a 27% hydrochloric acid solution to form a mixed solution E. The mixed solution E was sealed and stirred at 50°C for 2 hours. When no obvious precipitate was formed in the solution, it was stirred open at 70°C for 5 hours. When the solution cooled to room temperature, Ru-based impregnation solution was obtained.

[0179] Ru-based impregnation solution was added dropwise to a pretreated Al2O3 support until no liquid precipitation occurred. After the addition was complete, the support was aged at room temperature for 10 hours, followed by 5 hours in a vacuum drying oven at 50°C. After drying, the support was placed in a muffle furnace and calcined at 400°C for 2 hours at a rate of 10°C / min. After calcination, the support was placed in a tubular reduction furnace and purged with a mixture of H2 and Ar at a volume ratio of 1:9 at 30°C for 2 hours. The temperature was then increased to 300°C at a rate of 10°C / min, and the support was reduced at 300°C with a mixture of H2 and Ar at a volume ratio of 1:9 for 5 hours. After reduction, the furnace was allowed to cool to room temperature, and the support was aged at room temperature for 10 hours with nitrogen and air at a volume ratio of 4:1. The Al2O3-supported Ru-based catalyst was obtained.

[0180] Testing revealed that the Al2O3-supported Ru-based catalyst prepared in Comparative Example 1 exhibited characteristic peaks of the (311), (400), and (440) crystal planes of γ-Al2O3 at positions of 37.5°, 46.5°, and 67.5°; the Ru on the catalyst surface... 0 Species and Ru 4+ The characteristic peaks of the species are at 461.8 eV and 464.8 eV, respectively; the reduction temperature of the Ru species is 247.1 °C.

[0181] from Figure 3 It is evident from the comparison that the catalyst prepared in this study does not contain five-coordinated Al. 3+ Five-coordinate Al 3+ The proportion is 0%.

[0182] from Figure 5 As can be seen from the results, the Ru particles attached to the catalyst prepared in this comparative example have a wide particle size distribution, and the number of particles of different sizes is not significantly different, indicating that the particle size control effect of Ru species is not ideal, and the average particle size is very large, reaching 12.6 nm.

[0183] from Figure 8 Figure 3 Figure 5 Figure 8 Figure 3 Figure 5 Figure 8It can be seen that the CO2 conversion rate of the catalyst prepared in the present comparative example increases with the increase of the reaction temperature, but the highest conversion rate is only about 60% within the temperature range of 0-400℃; it can also be seen that the CH4 selectivity of the catalyst prepared in the present comparative example is relatively high, and is higher than 90% before 300℃, and the selectivity gradually decreases when the temperature is higher than 300℃; in combination of the CO2 conversion rate and the CH4 selectivity of the catalyst, it can be seen that, within the temperature range of 300-400℃, the decrease of the CH4 selectivity is obviously lower than the increase of the CO2 conversion rate, and therefore the catalyst prepared in the present comparative example exhibits excellent catalytic performance at a temperature higher than 300℃, but the catalytic performance, especially the CO2 conversion rate, significantly decreases at a low temperature of 300℃ or below, and cannot meet the demand of low-temperature catalysis.

[0184] Comparative Example 2

[0185] Aluminum isopropoxide and P123 in a molar ratio of 10:3.5 were added into a mixed solvent of isopropanol and ultrapure water in a volume ratio of 1:3 to form a mixed solution A. The mass ratio of aluminum isopropoxide to the mixed solvent was 1:4. After the mixed solution A was stirred at room temperature for 0.5 hours, an ammonia solution was added dropwise, the pH value of the mixed solution was adjusted to 8.5, and the stirring was continued for 1 hour to form a mixed solution B. The mixed solution B was placed in a constant-temperature water bath at 70℃ and continuously stirred for 1 hour under the assistance of a mechanical stirrer to form a mixed solution C.

[0186] The mixed solution C was transferred into the liner of a solvothermal reactor, and the reactor was sealed. Then, the solvothermal reactor containing the solution C was transferred into a blast drying oven at 160℃ and kept for 24 hours. After the solvothermal reaction was completed, the reactor was taken out of the blast drying oven, and the white powder in the reactor was taken out when the temperature decreased to room temperature. The powder was washed to neutral with a mixed solvent of ultrapure water and ethanol in a volume ratio of 3:1, and then dried in a blast drying oven at 120℃ for 24 hours. After the drying was completed, the white powder was placed in a muffle furnace, and the muffle furnace was raised to 550℃ at a rate of 10℃ / min, and then calcined at 550℃ for 5 hours to obtain an Al2O3 carrier with five-coordinated Al 3+ .

[0187] The Al2O3 carrier with five-coordinated Al 3+Al2O3 carrier powder into a 27% mass concentration hydrochloric acid solution to form a mixed solution D, wherein the mass ratio of the Al2O3 powder to the hydrochloric acid solution is 1:2; after the mixed solution D is stirred at room temperature for 1 hour, the powder is washed to neutral with a mixed solvent of ultrapure water and ethanol in a volume ratio of 3:1, and the step is repeated 3 times; after the washing is completed, the Al2O3 powder is placed in a blast drying oven, dried at 120°C in the blast drying oven for 12 hours, and then placed in a muffle furnace, heated to 400°C at a rate of 10°C / min, and calcined for 2 hours; after the calcination is completed, a pre-processed Al2O3 carrier with five-coordinated Al 3+ is obtained.

[0188] The RuCl3 powder is placed in a 27% mass concentration hydrochloric acid solution to form a mixed solution E, and the mixed solution E is stirred at 50°C for 2 hours with a sealed opening, and after no obvious precipitate is precipitated in the solution, the stirring is continued at 70°C for 5 hours with an open container, and the solution is cooled to room temperature to obtain a Ru-based impregnation liquid.

[0189] The Ru-based impregnation liquid is added dropwise to the pre-processed Al2O3 carrier with five-coordinated Al 3+ , until no liquid is precipitated. After the dropwise addition is completed, the solution is aged at room temperature for 5 hours, and then dried in a vacuum drying oven at 50°C for 5 hours; after the drying is completed, the solution is placed in a muffle furnace, heated to 400°C at a rate of 10°C / min, and calcined for 2 hours; after the calcination is completed, the solution is placed in a tube furnace, and a mixed gas of H2 and Ar in a volume ratio of 1:9 is passed through the solution at a temperature of 30°C for 2 hours; then the temperature is increased to 300°C at a rate of 10°C / min, and the mixed gas of H2 and Ar in a volume ratio of 1:9 is used to reduce the solution at 300°C for 5 hours. After the reduction is completed, the tube furnace is cooled to room temperature, and a mixed gas of nitrogen and air in a volume ratio of 4:1 is used to age the solution at room temperature for 10 hours. Thus a Sabatier reaction catalyst is obtained.

[0190] Tests show that the Sabatier reaction catalyst prepared in Example 1 exhibits characteristic peaks of (311) crystal plane, (400) crystal plane and (440) crystal plane of γ-Al2O3 at positions of 37.5°, 46.5° and 67.5°, respectively; the characteristic peaks of Ru 0 species and Ru 4+ species on the surface of the catalyst are at 461.8 eV and 464.3 eV, respectively; the reduction temperature of the Ru species is 203.6°C; and the CO2 conversion rate and CH4 selectivity of the catalyst in the low temperature zone (300°C) can reach 75.3% and 89.6%, respectively.

[0191] Comparative Example 3

[0192] The aluminum isopropoxide and urea with a molar ratio of 10:3.5 were added into a mixed solvent of isopropyl alcohol and ultrapure water with a volume ratio of 1:3 to form a mixed solution A. The mass ratio of aluminum isopropoxide to the mixed solvent was 1:4. After the mixed solution A was stirred at room temperature for 0.5 hours, an ammonia solution was added dropwise, the pH value of the mixed solution was adjusted to 8.5, and the stirring was continued for 1 hour to form a mixed solution B. The mixed solution B was placed in a constant temperature water bath at 70°C and continuously stirred with the aid of a mechanical stirrer for 1 hour to form a mixed solution C.

[0193] The white powder in the mixed solution C was taken out and washed with a mixed solvent of ultrapure water and ethanol with a volume ratio of 3:1 until neutral. Then the powder was placed in a blast drying oven at 120°C and dried for 24 hours. After the drying was completed, the white powder was placed in a muffle furnace, the muffle furnace was raised to 550°C at a rate of 10°C / min, and calcination was performed at 550°C for 5 hours to obtain an Al2O3 carrier with five-coordinated Al 3+ .

[0194] The Al2O3 carrier powder with five-coordinated Al 3+ was added into a hydrochloric acid solution with a mass concentration of 27% to form a mixed solution D. The mass ratio of the Al2O3 powder to the hydrochloric acid solution was 1:2. After the mixed solution D was stirred at room temperature for 1 hour, the powder was washed with a mixed solvent of ultrapure water and ethanol with a volume ratio of 3:1 until neutral. After the washing was repeated for 3 times, the Al2O3 powder after washing was placed in a blast drying oven and dried at 120°C for 12 hours. Then the powder was placed in a muffle furnace and calcined at a rate of 10°C / min to 400°C for 2 hours. After the calcination was completed, a pretreated Al2O3 carrier with five-coordinated Al 3+ was obtained.

[0195] The RuCl3 powder was placed in a hydrochloric acid solution with a mass concentration of 27% to form a mixed solution E. The mixed solution E was stirred at 50°C for 2 hours with a sealed cap. After no obvious precipitate was precipitated in the solution, the stirring was continued at 70°C for 5 hours with an open cap. After the solution was cooled to room temperature, a Ru-based impregnation solution was obtained.

[0196] The Ru-based impregnation solution was added dropwise to the pretreated Al2O3 carrier with five-coordinated Al 3+The Al2O3 support was dried until no liquid precipitated. After the addition was complete, the mixture was aged at room temperature for 5 hours, then dried in a vacuum drying oven at 50°C for 5 hours. After drying, it was placed in a muffle furnace and calcined at 400°C for 2 hours at a rate of 10°C / min. After calcination, it was placed in a tubular reduction furnace and purged with a mixture of H2 and Ar at a volume ratio of 1:9 at 30°C for 2 hours. Then, the temperature was increased to 300°C at a rate of 10°C / min, and reduced with a mixture of H2 and Ar at a volume ratio of 1:9 at 300°C for 5 hours. After reduction, the furnace was allowed to cool to room temperature, and the mixture was aged at room temperature for 10 hours using nitrogen and air at a volume ratio of 4:1. The Sabatier reaction catalyst was then obtained.

[0197] Testing revealed that the Sabatier reaction catalyst prepared in Example 1 exhibited characteristic peaks of the (311), (400), and (440) crystal planes of γ-Al₂O₃ at positions of 37.5°, 46.5°, and 67.5°; the Ru on the catalyst surface... 0 Species and Ru 4+ The characteristic peaks of the species are at 461.6 eV and 464.1 eV, respectively; the reduction temperature of the Ru species is 221.6 °C; the catalyst achieves CO2 conversion and CH4 selectivity of 64.3% and 79.5% in the low-temperature region (300 °C), respectively.

[0198] Comparative Example 4

[0199] Aluminum isopropoxide and urea in a molar ratio of 10:3.5 were added to a mixed solvent of isopropanol and ultrapure water in a volume ratio of 1:3 to form mixed solution A. The mass ratio of aluminum isopropoxide to the mixed solvent was 1:4. Mixed solution A was stirred at room temperature for 0.5 hours, and then ammonia solution was added dropwise to adjust the pH to 12. Stirring was continued for 1 hour to form mixed solution B. Mixed solution B was placed in a 70°C constant temperature water bath and stirred continuously for 1 hour with the aid of a mechanical stirrer to form mixed solution C.

[0200] Mixed solution C was transferred to the lining of a solvothermal reactor. After sealing the reactor, the solvothermal reactor containing solution C was transferred to a 160°C drying oven and kept there for 24 hours. After the solvothermal reaction was completed, the reactor was removed from the drying oven and allowed to cool to room temperature. The white powder was then removed from the reactor and washed with a mixed solvent of ultrapure water and ethanol (volume ratio 3:1) until neutral. The powder was then dried in a 120°C drying oven for 24 hours. After drying, the white powder was placed in a muffle furnace, and the furnace temperature was increased to 550°C at a rate of 10°C / min. The powder was then calcined at 550°C for 5 hours to obtain Al with five coordination groups. 3+ Al2O3 carrier.

[0201] Al2O3 support powder with pentacoordinated Al 3+ was added into a hydrochloric acid solution with a mass concentration of 27% to form a mixed solution D, wherein the mass ratio of the Al2O3 powder to the hydrochloric acid solution was 1:2; after the mixed solution D was stirred at room temperature for 1 hour, the powder was washed to neutral with a mixed solvent of ultrapure water and ethanol with a volume ratio of 3:1, and the step was repeated for 3 times; after the washing was completed, the Al2O3 powder was placed into a blast drying oven, dried at 120°C for 12 hours, and then placed into a muffle furnace, heated to 400°C at a rate of 10°C / min, and calcined for 2 hours; after the calcination was completed, a pretreated Al2O3 support with pentacoordinated Al 3+ was obtained.

[0202] RuCl3 powder was placed into a hydrochloric acid solution with a mass concentration of 27% to form a mixed solution E; the mixed solution E was sealed and stirred at 50°C for 2 hours, and after no obvious precipitate was precipitated from the solution, the solution was continuously stirred at 70°C for 5 hours in an open state; after the solution was cooled to room temperature, a Ru-based impregnation liquid was obtained.

[0203] The Ru-based impregnation liquid was added dropwise into the pretreated Al2O3 support with pentacoordinated Al 3+ ; until no liquid was precipitated. After the dropwise addition was completed, the solution was aged at room temperature for 5 hours, and then dried in a vacuum drying oven at 50°C for 5 hours; after the drying was completed, the solution was placed into a muffle furnace, heated to 400°C at a rate of 10°C / min, and calcined for 2 hours; after the calcination was completed, the solution was placed into a tube-type reduction furnace, and a mixed gas of H2 and Ar with a volume ratio of 1:9 was passed through the solution at a temperature of 30°C for 2 hours; then the temperature was increased to 300°C at a rate of 10°C / min, and the mixed gas of H2 and Ar with a volume ratio of 1:9 was used to reduce the solution at 300°C for 5 hours. After the reduction was completed, the reduction furnace was cooled to room temperature, and a mixed gas of nitrogen and air with a volume ratio of 4:1 was used to age the solution at room temperature for 10 hours. Thus, a Sabatier reaction catalyst was obtained.

[0204] Test results show that the Sabatier reaction catalyst prepared in Example 1 presents characteristic peaks of (311) crystal plane, (400) crystal plane and (440) crystal plane of γ-Al2O3 at positions of 37.5°, 46.5° and 67.5°, respectively; characteristic peaks of Ru 0 species and Ru 4+ species on the surface of the catalyst are at 461.8 eV and 464.3 eV, respectively; the reduction temperature of the Ru species is 227.6°C; and the CO2 conversion rate and CH4 selectivity of the catalyst in a low-temperature zone (300°C) can reach 51.7% and 83.5%, respectively.

[0205] Comparative Example 5

[0206] A mixture solution A was prepared by adding aluminum isopropoxide and urea in a molar ratio of 10:3.5 into a mixed solvent of isopropyl alcohol and ultrapure water in a volume ratio of 1:3. The mass ratio of aluminum isopropoxide to the mixed solvent was 1:4. After the mixture solution A was stirred at room temperature for 0.5 hours, an ammonia solution was added dropwise to adjust the pH value of the mixture solution to 8.5. After the mixture solution was continuously stirred for 1 hour, a mixture solution B was formed. The mixture solution B was placed in a thermostatic water bath at 70°C and continuously stirred with the aid of a mechanical stirrer for 1 hour to form a mixture solution C.

[0207] The mixture solution C was transferred into the liner of a solvothermal reactor. After the reactor was sealed, the solvothermal reactor containing the solution C was transferred into a blast drying oven at 90°C and kept for 24 hours. After the solvothermal reaction was completed, the reactor was taken out of the blast drying oven, and the white powder in the reactor was taken out after the temperature dropped to room temperature. The powder was washed to neutral with a mixed solvent of ultrapure water and ethanol in a volume ratio of 3:1, and then the powder was dried in a blast drying oven at 120°C for 24 hours. After the drying was completed, the white powder was placed in a muffle furnace, and the muffle furnace was raised to 550°C at a rate of 10°C / min and calcined at 550°C for 5 hours to obtain an Al2O3 support with pentacoordinate Al 3+ .

[0208] The Al2O3 support powder with pentacoordinate Al 3+ was added into a hydrochloric acid solution with a mass concentration of 27% to form a mixture solution D. The mass ratio of the Al2O3 powder to the hydrochloric acid solution was 1:2. After the mixture solution D was stirred at room temperature for 1 hour, the powder was washed to neutral with a mixed solvent of ultrapure water and ethanol in a volume ratio of 3:1. After the washing was repeated for 3 times, the Al2O3 powder after the washing was placed in a blast drying oven and dried at 120°C for 12 hours. Then, the powder was placed in a muffle furnace and calcined at a rate of 10°C / min to 400°C for 2 hours. After the calcination was completed, a pretreated Al2O3 support with pentacoordinate Al 3+ was obtained.

[0209] RuCl3 powder was placed in a hydrochloric acid solution with a mass concentration of 27% to form a mixture solution E. The mixture solution E was stirred at 50°C for 2 hours. After no obvious precipitate was precipitated in the solution, the solution was continuously stirred at 70°C for 5 hours. After the solution was cooled to room temperature, a Ru-based impregnation solution was obtained.

[0210] The Ru-based impregnation solution was added dropwise to the pretreated Al2O3 support with pentacoordinate Al 3+The Al2O3 support was dried until no liquid precipitated. After the addition was complete, the mixture was aged at room temperature for 5 hours, then dried in a vacuum drying oven at 50°C for 5 hours. After drying, it was placed in a muffle furnace and calcined at 400°C for 2 hours at a rate of 10°C / min. After calcination, it was placed in a tubular reduction furnace and purged with a mixture of H2 and Ar at a volume ratio of 1:9 at 30°C for 2 hours. Then, the temperature was increased to 300°C at a rate of 10°C / min, and reduced with a mixture of H2 and Ar at a volume ratio of 1:9 at 300°C for 5 hours. After reduction, the furnace was allowed to cool to room temperature, and the mixture was aged at room temperature for 10 hours using nitrogen and air at a volume ratio of 4:1. The Sabatier reaction catalyst was then obtained.

[0211] Testing revealed that the Sabatier reaction catalyst prepared in Example 1 exhibited characteristic peaks of the (311), (400), and (440) crystal planes of γ-Al₂O₃ at positions of 37.5°, 46.5°, and 67.5°; the Ru on the catalyst surface... 0 Species and Ru 4+ The characteristic peaks of the species are at 461.8 eV and 464.3 eV, respectively; the reduction temperature of the Ru species is 231.8 °C; the catalyst achieves CO2 conversion and CH4 selectivity of 65.3% and 81.6% in the low-temperature region (300 °C), respectively.

[0212] Comparative Example 6

[0213] Aluminum isopropoxide and urea in a molar ratio of 10:3.5 were added to a mixed solvent of isopropanol and ultrapure water in a volume ratio of 1:3 to form mixed solution A. The mass ratio of aluminum isopropoxide to the mixed solvent was 1:4. Mixed solution A was stirred at room temperature for 0.5 hours, and then ammonia solution was added dropwise to adjust the pH to 8.5. Stirring continued for 1 hour to form mixed solution B. Mixed solution B was placed in a 70°C constant temperature water bath and stirred continuously for 1 hour with the aid of a mechanical stirrer to form mixed solution C.

[0214] Mixed solution C was transferred to the lining of a solvothermal reactor. After sealing the reactor, the solvothermal reactor containing solution C was transferred to a 160°C forced-air drying oven and kept there for 48 hours. After the solvothermal reaction was completed, the reactor was removed from the forced-air drying oven. Once the temperature had dropped to room temperature, the white powder was removed from the reactor and washed with a 3:1 (volume ratio of ultrapure water to ethanol) mixed solvent until neutral. The powder was then placed in a 120°C forced-air drying oven and dried for 24 hours. After drying, the white powder was placed in a muffle furnace, and the furnace temperature was increased to 550°C at a rate of 10°C / min. The powder was then calcined at 550°C for 5 hours to obtain Al with five coordination groups. 3+ Al2O3 carrier.

[0215] Al2O3 support powder with pentacoordinated Al 3+ was added into a 27% mass concentration hydrochloric acid solution to form a mixed solution D, wherein the mass ratio of the Al2O3 powder to the hydrochloric acid solution was 1:2; after the mixed solution D was stirred at room temperature for 1 hour, the powder was washed to neutral with a mixed solvent of ultrapure water and ethanol in a volume ratio of 3:1, and the step was repeated for 3 times; after the Al2O3 powder after the washing was completed was placed into a blast drying oven, dried at 120°C in the blast drying oven for 12 hours, and then placed into a muffle furnace, heated to 400°C at a speed of 10°C / min, and calcined for 2 hours; after the calcination was completed, a pretreated Al2O3 support with pentacoordinated Al 3+ was obtained.

[0216] RuCl3 powder was placed into a 27% mass concentration hydrochloric acid solution to form a mixed solution E; the mixed solution E was sealed and stirred at 50°C for 2 hours, and after no obvious precipitate was separated out from the solution, the solution was continuously stirred at 70°C for 5 hours in an open state, and then the solution was cooled to room temperature to obtain a Ru-based impregnation solution.

[0217] The Ru-based impregnation solution was added dropwise into the pretreated Al2O3 support with pentacoordinated Al 3+ , until no liquid was separated out. After the dropwise addition was completed, the solution was aged at room temperature for 5 hours, and then dried in a vacuum drying oven at 50°C for 5 hours; after the drying was completed, the solution was placed into a muffle furnace, heated to 400°C at a speed of 10°C / min, and calcined for 2 hours; after the calcination was completed, the solution was placed into a tube-type reduction furnace, and a mixed gas of H2 and Ar in a volume ratio of 1:9 was passed through the solution at a temperature of 30°C for 2 hours; then the temperature was increased to 300°C at a speed of 10°C / min, and the mixed gas of H2 and Ar in a volume ratio of 1:9 was used to reduce the solution at the temperature of 300°C for 5 hours. After the reduction was completed, the reduction furnace was cooled to room temperature, and a mixed gas of nitrogen and air in a volume ratio of 4:1 was used to age the solution at room temperature for 10 hours. Thus a Sabatier reaction catalyst was obtained.

[0218] Test results show that the Sabatier reaction catalyst prepared in Example 1 presents characteristic peaks of (311) crystal face, (400) crystal face and (440) crystal face of γ-Al2O3 at positions of 37.5°, 46.5° and 67.5° respectively; characteristic peaks of Ru 0 species and Ru 4+ species on the surface of the catalyst are at 461.8 eV and 464.3 eV respectively; the reduction temperature of the Ru species is 202.7°C; and the CO2 conversion rate and CH4 selectivity of the catalyst in a low temperature zone (300°C) can reach 89.5% and 90.7% respectively.

[0219] Experimental Example One

[0220] This experimental example summarizes the performance of the catalysts prepared in the above examples and comparative examples, as shown in the table below:

[0221] It should be noted that the CO2 conversion rate and CH4 selectivity in the table below were measured at a temperature of 300℃.

[0222] Five-coordinate Al 3+ The proportion is used 27 Al NMR ( 27 The results were obtained using Al-NMR (Al-NMR) and were measured using a Swiss BRUKER AC-80 nuclear magnetic resonance spectrometer at a frequency of 80 MHz with a broadband multi-nuclear probe.

[0223] Specific surface area was determined using the Autosorb-iQ fully automated specific surface area and pore size distribution analyzer from Quantachrome, USA. The N2 adsorption-desorption curves were measured in a liquid nitrogen atmosphere, the specific surface area was calculated according to the BET equation, and the pore structure data were deduced based on the BJH model.

[0224] The Ru particle size was determined by counting approximately 50 particles from transmission electron microscopy (TEM) images of the catalyst. The TEM system used was a JEOL JEM-F200 system equipped with a STEM detector and an energy dispersive spectroscopy (EDS) spectrometer. The accelerating voltage was 200 kV, and the resolution was 0.19 nm.

[0225]

[0226]

[0227] As can be seen from the table above, the preparation processes of Example 1 and Comparative Example 2 are completely identical, the only difference being the inducing agent used. In Example 1, urea was used as the inducing agent, while in Comparative Example 2, P123 was used. Compared to Comparative Example 2, the Al2O3 prepared using urea as the inducing agent in Example 1 has five-coordinated Al atoms. 3+ The proportion of urea increased significantly, the Ru species had a smaller particle size, and the CO2 conversion rate and CH4 selectivity were higher. This is because, compared to P123, the molecular spatial structure of urea can better induce five-coordinated Al. 3+ The formation of Ru and the increase of active sites are conducive to the adsorption and dispersion of Ru, which in turn leads to a reduction in Ru particle size and a significant improvement in catalytic efficiency and product selectivity.

[0228] Furthermore, the only difference between Example 1 and Comparative Example 3 is that the solvothermal reaction step was omitted in Comparative Example 3. It can be observed that, compared to Example 1, the five-coordinated Al in Comparative Example 3... 3+The proportion is obviously reduced, only 6.8%, which shows that the simple use of urea as an inducer cannot achieve excellent induction effect, and the solvothermal reaction process can greatly promote the induction ability of urea as an inducer; the second comparative example can further illustrate that the solvothermal reaction only has a synergistic and amplification effect on specific inducers.

[0229] Further, the difference between example one and comparative example four is only that the pH is different in the preparation of five-coordinated Al 3+ Al2O3, it can be seen that the pH of comparative example four is 12, and the pH of example one is 8.5, although the precursor of the Al2O3 carrier needs to be prepared under alkaline conditions, only in a specific pH range can the efficient generation of five-coordinated Al 3+ be ensured, if the pH is too high, it will lead to the generation of other transition species, which ultimately leads to the reduction of the content of five-coordinated Al 3+ .

[0230] In addition, it can also be seen from the above table that the temperature and length of the solvothermal reaction also have a very obvious effect on the performance of the final catalyst, the solvothermal reaction temperature of example one is 160°C, and the solvothermal reaction temperature of comparative example five is 90°C, that is, within the temperature range of 50-200°C, higher temperature is conducive to the synergistic effect between the solvothermal reaction and the selected catalyst, and the solvothermal reaction temperatures of example two, example three and example four are all between 150-180°C, so it can be seen that controlling the solvothermal reaction temperature at 150-180°C is more conducive to improving the performance of the catalyst; the length of the solvothermal reaction of example one is 24h, and the length of the reaction of comparative example six is 48h; although the proportion of five-coordinated Al 3+ of comparative example six is increased, the conversion rate and product selectivity are not further improved.

[0231] The above is only the preferred embodiment of the present application, and is not intended to limit the present application in any form, although the present application has been disclosed as above with the preferred embodiment, however, it is not intended to limit the present application, any person skilled in the art can make some changes or modifications to the above-mentioned technical content without departing from the scope of the technical solution of the present application, the implementation scheme in the above examples can be further combined or replaced, as long as it does not deviate from the content of the technical solution of the present application, any simple modification, equivalent change and modification of the above examples according to the technical essence of the present application, all still belong to the scope of the present application.

Claims

1. A method for preparing a Sabatier reaction catalyst, characterized by, The method comprises the following steps: S1, an aluminum-based salt and an inducing agent are mixed, the pH of the mixed solution is adjusted to 7.5-9, an alcohol aluminum hydrolysis reaction is carried out, and then a solvent thermal reaction and post-treatment are performed to obtain an Al2O3 support with five-coordinated Al 3+ . The temperature of the solvothermal reaction is 150-200℃, and the time length of the solvothermal reaction is 18h-100h; the inducing agent is urea. S2. Pre-treatment of the Al2O3 support prepared in step S1 with an acid solution having five-coordinated Al 3+ ; S3, attaching the Ru-based impregnation solution to the surface of the Al2O3 carrier pretreated in step S2, and obtaining the Sabatier reaction catalyst through treatment.

2. The method of claim 1, wherein the Sabatier reaction catalyst is prepared by the steps of: In step S1, the alcoholysis reaction of aluminum alkoxide is carried out at a temperature of 50-120℃.

3. The method of claim 1, wherein the Sabatier reaction catalyst is prepared by the steps of: In step S1, the pH adjusting agent used for adjusting the pH of the mixed solution is one or more of ammonia, sodium hydroxide, potassium hydroxide, sodium bicarbonate or sodium carbonate.

4. The method of claim 1, wherein the Sabatier reaction catalyst is prepared by the steps of: In step S1, the pH adjusting agent is ammonia.

5. The method of claim 1, wherein the Sabatier reaction catalyst is prepared by the steps of: In step S1, the pH of the mixed solution is adjusted to 8.5-9.

6. The method of claim 1, wherein the Sabatier reaction catalyst is prepared by the steps of: The process of the solvothermal reaction is: after the alcoholysis reaction of aluminum alkoxide is completed, the mixed solution is transferred to a sealed container for reaction.

7. The method of claim 1, wherein the Sabatier reaction catalyst is prepared by the steps of: The temperature of the solvothermal reaction is 150-180℃.

8. The method of claim 1, wherein the Sabatier reaction catalyst is prepared by the steps of: The time length of the solvothermal reaction is 24h.

9. The method of claim 1, wherein the Sabatier reaction catalyst is prepared by the steps of: The aluminum-based salt and the inducing agent are mixed at a temperature of 20-50℃ to obtain a mixed solution, and the solvent of the mixed solution is a mixture of water and an organic solvent.

10. The method of claim 9, wherein the Sabatier reaction catalyst is prepared by the steps of: The mixing temperature is 30℃.

11. The method of claim 9, wherein the Sabatier reaction catalyst is prepared by the steps of: After mixing, the mixed solution is stirred for 0.1h-10h.

12. The method of claim 11, wherein the Sabatier reaction catalyst is prepared by the steps of: The stirring time length is 1h.

13. The method of claim 9, wherein the Sabatier reaction catalyst is prepared by the steps of: The aluminum-based salt and the inducing agent are mixed at a molar ratio of 100: (1-100).

14. The method for preparing the Sabatier reaction catalyst according to claim 9, characterized in that, The aluminum-based salt and the inducing agent are mixed at a molar ratio of 100:

35.

15. The method of claim 9, wherein the Sabatier reaction catalyst is prepared by the steps of: The mass ratio of the aluminum-based salt to the solvent is 1: (1-10).

16. The method of claim 9, wherein the Sabatier reaction catalyst is prepared by the steps of: The organic solvent is selected from one or more of ethanol, propanol, butanol, isopropanol or N,N dimethylformamide.

17. The method of claim 9, wherein the Sabatier reaction catalyst is prepared by the steps of: The solvent of the mixed solution is a mixture of isopropanol and water.

18. The method of claim 17, wherein the Sabatier reaction catalyst is prepared by a method comprising: The volume ratio of isopropanol to water is 1:

3.

19. The method of claim 1-18, wherein the Sabatier reaction catalyst is prepared by, In step S1, the post-treatment comprises washing, drying and calcination performed in sequence. The calcination temperature is 300-1000℃.

20. The method of claim 19, wherein the Sabatier reaction catalyst is prepared by a method comprising: The calcination temperature is 550℃.

21. The method of claim 19, wherein the Sabatier reaction catalyst is prepared by a method comprising: The calcination temperature is 550℃.

22. The method of claim 19, wherein the Sabatier reaction catalyst is prepared by the steps of: The calcination temperature is 550℃.

23. The method of claim 1-18, wherein the Sabatier reaction catalyst is prepared by the steps of: The calcination temperature is 550℃. The Al2O3 support having pentacoordinated Al 3+ from Step S1 is impregnated in an acid, then washed, dried and calcined to obtain a pretreated Al2O3 support having pentacoordinated Al 3+ .

24. The method of claim 23, wherein the Sabatier reaction catalyst is prepared by the steps of: Step S2 specifically comprises:

25. The method of claim 23, wherein the Sabatier reaction catalyst is prepared by the steps of: The acid used for impregnation is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid.

26. The method of claim 23, wherein the Sabatier reaction catalyst is prepared by the steps of: The cleaning agent is a mixture of ethanol and water with a volume ratio of 1:

3.

27. The method for preparing the Sabatier reaction catalyst according to claim 23, characterized in that, The calcination temperature is 20-1000℃.

28. The method of claim 1-18, wherein the Sabatier reaction catalyst is prepared by, The calcination temperature is 400℃, and the calcination time length is 1-24h. Step S3 specifically comprises:

29. The method of claim 28, wherein the Sabatier reaction catalyst is prepared by a method comprising: The Ru-based impregnation solution is dropped onto the surface of the Al2O3 carrier pretreated in step S2 until no liquid is precipitated, and then the Sabatier reaction catalyst is obtained through heat preservation, drying and calcination.

30. The method of claim 28, wherein the Sabatier reaction catalyst is prepared by a method comprising: The heat preservation temperature is 20-90℃.

31. The method of claim 28, wherein the Sabatier reaction catalyst is prepared by a method comprising: The heat preservation temperature is 30℃.

32. The method of claim 31, wherein the Sabatier reaction catalyst is prepared by a method comprising: The Ru-based impregnation solution is an acid solution of a Ru-based precursor.

33. The method of claim 31, wherein the Sabatier reaction catalyst is prepared by a method comprising: The preparation process of the Ru-based impregnation solution is: the Ru-based precursor is dissolved in an acid solution, sealed and stirred until no obvious precipitate is precipitated, and then stirred in an open state to obtain the Ru-based impregnation solution.

34. The method of claim 31, wherein the Sabatier reaction catalyst is prepared by a method comprising: The Ru-based precursor is selected from one or more of ruthenium chloride, ruthenium acetate, ruthenium acetylacetone, ruthenium sulfate and ruthenium oxide.

35. The method for preparing the Sabatier reaction catalyst according to claim 31, characterized in that, The acid in the Ru-based impregnation solution is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid.

36. The method of claim 28, wherein the Sabatier reaction catalyst is prepared by a method comprising: The Ru-based precursor is ruthenium chloride, and the acid in the Ru-based impregnation solution is a hydrochloric acid solution. In step S3, the calcination temperature ranges from 100-1000℃, and the temperature rising rate of the calcination temperature is 0.1-50℃ / min.

37. The method for preparing the Sabatier reaction catalyst according to claim 36, characterized in that, The calcination temperature is 400℃; the temperature rising rate is 10℃ / min.

38. The method for preparing the Sabatier reaction catalyst according to claim 28, characterized in that, The calcination time is 0.1-10h.

39. The method for preparing the Sabatier reaction catalyst according to claim 28, characterized in that, The calcination time is 2h.

40. Use of a catalyst prepared according to the method of any one of claims 1-39, wherein, Used as a catalyst for Sabatier reaction The catalytic temperature when used as a catalyst for Sabatier reaction is 275-300℃ The conversion rate for CO2 at a catalytic temperature of 300℃ is higher than 60%.

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