Metal-modified molecular sieve, method for preparing the same, and use thereof
By using the metal-modified molecular sieve CabCuOx/ZSM-23 catalyst, the problems of poor thermal stability and low CO selectivity of existing catalysts in the reaction of carbon dioxide hydrogenation to carbon monoxide were solved, realizing the efficient conversion of carbon dioxide to carbon monoxide at low temperature and improving the stability and selectivity of the catalyst.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-13
- Publication Date
- 2026-06-16
AI Technical Summary
Existing catalysts for the hydrogenation of carbon dioxide to carbon monoxide suffer from poor thermal stability, low CO selectivity, and high cost. In particular, copper-based catalysts have insufficient thermal stability, nickel-based catalysts have poor CO selectivity, and precious metal catalysts are expensive and prone to deactivation.
Using the metal-modified molecular sieve CabCuOx/ZSM-23 as a catalyst, carbon dioxide is directly converted into carbon monoxide under mild conditions through the tight binding of copper and calcium and the specific structure of ZSM-23 molecular sieve, exhibiting high activity and selectivity.
It improves catalytic activity, selectivity and stability, and achieves efficient conversion of carbon dioxide to carbon monoxide at low temperatures, significantly reducing energy consumption.
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Figure CN122209461A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of carbon dioxide conversion and utilization, specifically relating to a metal-modified molecular sieve, its preparation method, and its application in the reaction of carbon dioxide hydrogenation to carbon monoxide. Background Technology
[0002] In recent years, environmental problems such as the greenhouse effect, ocean acidification, and global warming caused by massive CO2 emissions have become increasingly serious, threatening human survival and development. Therefore, CO2 emission reduction and resource utilization have become a focus of attention for countries around the world. At the same time, CO2 is also an economical, safe, and renewable carbon resource. After collecting CO2 from the atmosphere, it can be catalytically converted into syngas, methanol, low-carbon olefins, aldehydes, acids, ethers, esters, and other chemicals through chemical reactions. This is currently considered by scientists to be the most promising solution.
[0003] Reverse water-gas shift reaction (CO2 + H2 = CO + H2O, ΔH) 298K The reverse water-gas shift reaction (41.2 kJ / mol) is considered one of the most promising CO2 conversion reactions. CO2 is converted into more valuable CO through this reaction, and the generated CO can then be used to synthesize methanol, hydrocarbon fuels, and other high-value-added chemical products. Simultaneously, this reaction can be coupled with reactions such as ethylbenzene dehydrogenation to styrene and low-carbon alkanes dehydrogenation to olefins, which can improve reaction performance, significantly reduce energy consumption, and enable the resource utilization of CO2. Therefore, developing catalysts with high activity and selectivity is of great significance in the research of reverse water-gas shift reactions.
[0004] Currently, catalysts used for this reaction mainly include Cu-based catalysts (Cu-Zn / Al2O3, Cu-Fe / Al2O3, Cu / SiO2, etc.), Ni-based catalysts (Ni / Al2O3, Ni / CeO2, etc.), and noble metal catalysts (Pt / TiO2, Rh / Al2O3, Pd-La2O3 / MWCNT). A common problem with copper-based catalysts is their poor thermal stability, making them difficult to apply in high-temperature carbon dioxide hydrogenation reactions. Even with the addition of promoters, their thermal stability and activity can be improved to some extent, but the improvement is limited (Chemical Communications, 2001, 1770-1771; Journal of the American Chemical Society, 2006, 128: 15950-15951.). The main problem with nickel-based catalysts is their poor CO selectivity. For example, although the Ni / CeO2 catalyst and K-modified Co-CeO2 catalyst disclosed in CN103183346A can achieve a CO yield of 35%-38% at 600℃, the catalysts are prone to carbon deposition and deactivation. While the Ni / Al2O3 catalyst has high activity, the methanation side reaction is quite serious during the reaction, generating a large amount of methane byproducts (Applied Catalysis A:General, 1997, 164(1):1-11.). Although noble metal catalysts have high activity (Applied Catalysis A:General, 2012, 423:100-107.), their high cost limits their industrial application. On the other hand, the catalysts currently used in this reaction mainly use reducing oxide supports (such as CeO2, TiO2, etc.), which are easily over-oxidized under high temperature and strong reducing reaction conditions, leading to rapid catalyst deactivation. Summary of the Invention
[0005] To address the above-mentioned technical problems, the present invention aims to provide a metal-modified molecular sieve, its preparation method, and its application in the hydrogenation reaction of carbon dioxide. The metal-modified molecular sieve provided by the present invention, as a catalyst in the hydrogenation reaction of carbon dioxide to carbon monoxide, can achieve the direct conversion of carbon dioxide to carbon monoxide under mild conditions, and exhibits outstanding catalytic activity, selectivity, and good stability.
[0006] To achieve the above objectives, the first aspect of the present invention provides a metal-modified molecular sieve, wherein the metal-modified molecular sieve is Ca. b CuO x / ZSM-23 molecular sieve;
[0007] Where b is 1.5 to 16, and x is the total number of oxygen atoms required to satisfy the oxidation states of each element in the metal oxide.
[0008] Furthermore, the metal-modified molecular sieve comprises a modified metal and a ZSM-23 molecular sieve, wherein the modified metal is Ca. b CuO x Where b is 1.5 to 16, and x is the total number of oxygen atoms required to satisfy the oxidation states of each element in the metal oxide.
[0009] Furthermore, in the metal-modified molecular sieve, based on the mass of the metal-modified molecular sieve, the mass content of calcium element is 2wt% to 8wt% (calculated as elemental calcium).
[0010] Furthermore, the total Brønsted acid content of pyridine in the ZSM-23 molecular sieve is 0.10–0.37 mmol / g, preferably 0.13–0.35 mmol / g, more preferably 0.15–0.33 mmol / g; and the total Brønsted acid content of 2,6-dimethylpyridine in the infrared is 0.07–0.35 mmol / g, preferably 0.09–0.33 mmol / g, more preferably 0.12–0.30 mmol / g.
[0011] Furthermore, the ratio of the total 2,6-dimethylpyridine infrared Brønsted acid content to the total pyridine infrared Brønsted acid content of the ZSM-23 molecular sieve is (65-99):100, preferably (70-97):100, and even more preferably (74-95):100.
[0012] Furthermore, in the 2,6-dimethylpyridine infrared acid of the ZSM-23 molecular sieve, the amount of weak Brønsted acid with a desorption temperature <250℃ is 0.09–0.31 mmol / g, preferably 0.11–0.29 mmol / g, and more preferably 0.13–0.28 mmol / g.
[0013] Furthermore, in the 2,6-dimethylpyridine infrared acid of the ZSM-23 molecular sieve, the ratio of the amount of weak Brønsted acid with a desorption temperature <250℃ to the total amount of Brønsted acid in the 2,6-dimethylpyridine infrared sieve is (64-95):100, preferably (67-93):100, and even more preferably (70-91):100.
[0014] Furthermore, the bulk SiO2 / Al2O3 (molar ratio) of the ZSM-23 molecular sieve is 40-400 higher than the outer surface SiO2 / Al2O3 (molar ratio), preferably 45-350 higher; the bulk SiO2 / Al2O3 (molar ratio) of the ZSM-23 molecular sieve is 80-500, and the outer surface SiO2 / Al2O3 (molar ratio) is 40-120; preferably, the bulk SiO2 / Al2O3 (molar ratio) is 90-400, and the outer surface SiO2 / Al2O3 (molar ratio) is 45-90.
[0015] A second aspect of the present invention provides a method for preparing the above-mentioned metal-modified molecular sieve, the method comprising:
[0016] (a) A copper salt solution was impregnated onto ZSM-23 molecular sieve, and after standing and drying, a first calcination was carried out to obtain a molecular sieve catalyst precursor.
[0017] (b) The calcium salt is impregnated into the molecular sieve catalyst precursor, dried, and calcined a second time to obtain the metal-modified molecular sieve.
[0018] Further, in step (a), the preparation method of the ZSM-23 molecular sieve includes the following steps:
[0019] (1) Mix silicon source, template agent a and water, and carry out crystallization reaction after mixing. After the reaction, the material is separated into solid and liquid to obtain solid material.
[0020] (2) Mix the solid material obtained in step (1) with aliphatic amine;
[0021] (3) Add an alkaline source solution to the material obtained in step (2) and perform a first low-temperature treatment; then add ZSM-23 seed crystals and perform a second low-temperature treatment;
[0022] (4) Prepare an aqueous solution containing template agent b and aluminum source, and then mix it with the material obtained in step (3) to obtain a gel. After crystallization, filtration, washing, drying and calcination, ZSM-23 molecular sieve is obtained.
[0023] Further, in step (1), the silicon source is one or more of silica, silica sol, water glass, fumed silica and tetraethyl orthosilicate, preferably silica and / or fumed silica.
[0024] Further, in step (1), the template agent a is at least one of hexamethylenediamine, ethanol and n-hexamethylenediamine, preferably hexamethylenediamine and / or ethanol.
[0025] Further, in step (1), the molar ratio of the template agent a to the silicon source (calculated as SiO2) is 0.1 to 1.0, preferably 0.15 to 0.8; the molar ratio of water to the silicon source (calculated as SiO2) is 20 to 80, preferably 30 to 70.
[0026] Further, in step (1), the crystallization reaction is carried out in a reaction vessel with a polytetrafluoroethylene liner, and the operating conditions are as follows: the crystallization temperature is 120-220°C, the crystallization time is 8-48h, preferably the crystallization temperature is 140-200°C, and the crystallization time is 12-30h.
[0027] Furthermore, in step (1), the solid-liquid separation can be achieved by any of the existing technologies in the art, such as gravity sedimentation, filtration separation and centrifugal separation, preferably centrifugal separation.
[0028] Furthermore, in step (2), the fatty amine is one or more of oleylamine (9-octadeceneamine), octadecamine, and dodecylamine, preferably oleylamine.
[0029] Further, in step (2), the liquid-to-solid ratio of the fatty amine to the solid material obtained in step (1) is 0.3 to 3 mL / g, preferably 0.5 to 2.0 mL / g.
[0030] Further, in step (3), the alkaline source used in the alkaline source solution is any one of sodium hydroxide, potassium hydroxide and ammonia water, and the concentration of the alkaline source solution is 0.003 to 0.015 mol / L, preferably 0.005 to 0.010 mol / L; the liquid-solid ratio of the alkaline source solution to the solid material obtained in step (1) is 2 to 20 mL / g, preferably 5 to 15 mL / g.
[0031] Further, in step (3), the temperature of the first low-temperature treatment is 20-40°C and the time is 3-15h; preferably, the temperature is 25-30°C and the time is 6-12h; the first low-temperature treatment is preferably carried out under stirring conditions, and the stirring rate is 100-300rpm.
[0032] Further, in step (3), the ZSM-23 seed crystals are added in the form of seed solution. The specific operation process of the seed solution is as follows: the ZSM-23 seed crystals are uniformly dispersed in water (preferably deionized water) to form seed solution; wherein, the liquid-solid ratio of water to ZSM-23 seed crystals is 5-70 mL / g, preferably 10-60 mL / g.
[0033] Further, in step (3), based on the weight of the solid material obtained in step (1), the amount of ZSM-23 seed crystals added is 0.1 to 8.0 wt%, preferably 0.5 to 5.0 wt%.
[0034] Further, in step (3), the second low-temperature treatment is performed at a temperature of 60-120°C for 6-30 hours; preferably, the temperature is 80-100°C for 12-24 hours; the second low-temperature treatment is preferably performed under stirring conditions, with a stirring rate of 100-300 rpm.
[0035] Further, in step (4), the template agent b is one or more of pyrrolidine, isopropylamine and N,N-dimethylformamide, preferably pyrrolidine; the aluminum source is one or more of aluminum sulfate, aluminum isopropoxide, sodium aluminate and aluminum hydroxide, preferably aluminum sulfate.
[0036] Further, in step (4), the aluminum source is calculated as Al2O3, and the solid material obtained in step (1) is calculated as SiO2. The molar ratio of template agent b to the solid material obtained in step (1) is 0.01 to 0.1, preferably 0.02 to 0.08; the molar ratio of aluminum source to the solid material obtained in step (1) is 0.002 to 0.015, preferably 0.005 to 0.01; and the molar ratio of water in the aqueous solution containing template agent b and aluminum source to aluminum source is 300 to 3000, preferably 400 to 2000.
[0037] Further, in step (4), the crystallization temperature is 180-220℃ and the crystallization time is 24-72h; the drying temperature is 80-120℃ and the drying time is 6-12h; the calcination temperature is 540-560℃ and the calcination time is 3-8h.
[0038] Further, in step (a), the copper salt is selected from at least one of copper nitrate and copper chloride.
[0039] Further, in step (a), the first calcination is carried out by programmed temperature rise calcination, with a heating rate of 2 to 10 °C / min, a calcination temperature of 450 to 650 °C, and a calcination time of 4 to 10 h.
[0040] Further, in step (b), the calcium salt is selected from at least one of calcium chloride and calcium bicarbonate.
[0041] Furthermore, in step (b), the mass ratio of copper salt, ZSM-23 molecular sieve, and calcium salt is 1:(5-20):(1-8).
[0042] Further, in step (b), the calcium salt is dissolved in water to prepare a calcium-containing solution. The amount of water added is selected according to the requirement of equal volume impregnation.
[0043] Furthermore, in step (a) or (b), the impregnation method employs equal-volume impregnation.
[0044] Furthermore, in step (a) or (b), the drying is each independently selected from operating conditions of 80–140°C and 8–24 h.
[0045] Furthermore, in (b), the second calcination is carried out using programmed temperature rise calcination, with a heating rate of 2 to 10 °C / min, a calcination temperature of 500 to 650 °C, and a calcination time of 4 to 10 h.
[0046] The third aspect of this invention provides the application of the above-mentioned metal-modified molecular sieve in the reaction of carbon dioxide hydrogenation to carbon monoxide.
[0047] Furthermore, the metal-modified molecular sieve needs to be pretreated with an H2 / N2 mixed gas before being used as a catalyst; the volume fraction of H2 in the mixed gas is 10-20%; the pretreatment temperature is 300-700℃, preferably 350-450℃, and the pretreatment time is 1-3 hours.
[0048] Furthermore, the reaction of hydrogenating carbon dioxide to produce carbon monoxide uses carbon dioxide and hydrogen as reaction gases.
[0049] Furthermore, the volume ratio of carbon dioxide to hydrogen in the reaction is 1:(1-4).
[0050] Furthermore, the reaction temperature is 200–600°C, preferably 250–500°C, the reaction time is 30–60 min, and the space velocity of carbon dioxide and hydrogen is 36–600 L / g / h.
[0051] Furthermore, the pressure of the reaction is not specifically limited, and conventional reaction pressure conditions in the art can be used, such as atmospheric pressure.
[0052] The present invention has the following advantages:
[0053] (1) The metal-modified molecular sieve provided by the present invention combines copper and calcium in a tight manner, and further combines with the ZSM-23 molecular sieve provided by the present invention to demonstrate a strong synergistic effect. When used as a catalyst in the reaction of carbon dioxide hydrogenation to carbon monoxide, it greatly improves the catalytic activity, selectivity and stability.
[0054] (2) The metal-modified molecular sieve of the present invention exhibits high low-temperature activity and CO selectivity as a catalyst in the reaction of carbon dioxide hydrogenation to carbon monoxide.
[0055] (3) In the preparation method of ZSM-23 molecular sieve provided by the present invention, an inexpensive template agent a is first selected to assist in the aging of silicon source to generate hydroxyl-rich molecular sieve primary structural unit silicon-oxygen tetrahedra and secondary structural units. Then, hydrophobic long-chain aliphatic amine molecules are combined with the hydroxyl groups on the surface of the structural units through hydrogen bonds and arranged in an orderly and uniformly dispersed manner. Afterwards, under the action of alkaline solution, they dissociate into uniform structural fragments with specific channels, and then rapidly assemble into pure silicon metastable ZSM-23 nanocrystals with the assistance of ZSM-23 seed crystals. Subsequently, Al species and template agent b combine to form chelates, which combine with hydroxyl groups at specific sites on the surface of metastable ZSM-23 nanocrystals. During high-temperature crystallization, they are embedded in the framework structure and grown into structurally stable ZSM-23 molecular sieves with a surface rich in weak Brønsted acid sites. The template agent used in this method is inexpensive and used in small quantities, which can achieve precise control of Al sites in ZSM-23 molecular sieves, which is conducive to the enrichment of its pores and weak Brønsted acid sites on the surface, thus significantly improving the reactivity of ZSM-23 molecular sieves with pore adsorption mechanism as the main mechanism. Moreover, in this invention, copper metal first occupies the Brønsted acid sites of the molecular sieve and remains in the micropores, while calcium is distributed on the surface, achieving high dispersion of the two metals and maximizing their synergistic effect.
[0056] (4) The metal-modified molecular sieve provided by the present invention is used as a catalyst in the reaction of carbon dioxide hydrogenation to carbon monoxide, exhibiting high low-temperature activity and CO selectivity, and the catalyst has outstanding stability. Attached Figure Description
[0057] Figure 1 The XRD pattern of ZSM-23 prepared in Example 1;
[0058] Figure 2 The reaction stability of the catalyst prepared in Example 5 was evaluated. Detailed Implementation
[0059] The catalyst of the present invention, its preparation method, and its effects are further illustrated below through examples. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.
[0060] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores.
[0061] In this invention, all molecular sieve samples used in various characterization tests have undergone ion exchange treatment. This ion exchange treatment can employ conventional methods found in existing technologies. Specifically, in this invention, ZSM-23 molecular sieves are placed in an ammonium salt solution with a concentration of 1-2 mol / L, where the liquid-to-solid ratio is 10-20. The solution is continuously stirred in a water bath at 70-90°C for 2-4 hours. This process can be repeated multiple times until the Na₂O content in the ZSM-23 molecular sieve after ammonium exchange is less than 0.1 wt%. Then, the samples are washed, dried, and calcined. The drying temperature is 80-120°C for 6-12 hours, and the calcination temperature is 500-550°C for 3-8 hours. The ammonium salt solution is selected from one or more of ammonium chloride or ammonium nitrate solutions.
[0062] More specifically, in this invention, the molecular sieve is placed in a 2 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 10, and stirred continuously in an 85°C water bath for 2 hours, followed by filtration and washing. This process is repeated twice until the Na₂O content in the ammonium-exchanged ZSM-23 molecular sieve is below 0.1 wt%. Then, the sample is washed, dried, and calcined. The sample is dried in a 100°C oven for 8 hours and calcined in air at 550°C for 3 hours to obtain H-ZSM-23 molecular sieve. Acidity testing and subsequent catalyst preparation are then performed.
[0063] In this invention, the pyridine infrared acid content was determined by pyridine adsorption infrared spectroscopy; the 2,6-dimethylpyridine infrared acid content was determined by 2,6-dimethylpyridine adsorption infrared spectroscopy. The acid content was calculated according to Lambert-Beer's law, using a 1540 cm⁻¹ spectroscopy method. -1 The acidity of Brønsted acid is calculated from the area of the absorption peak.
[0064] In this invention, the acid content of different intensities at the pore openings and outer surface of molecular sieves is determined by 2,6-dimethylpyridine adsorption infrared spectroscopy. The specific process is as follows: the molecular sieve sample is prepared into a self-supporting wafer (5-6 mg / cm²). 2 The sample was placed in an in-situ cell and treated under vacuum at 400℃ for 4 hours, then cooled to 50℃, and the spectrum was collected. After adsorbing 2,6-dimethylpyridine for 10 minutes, the sample was heated to 150℃ for desorption for 1 hour, cooled to room temperature, and the spectrum was collected. At this time, the total amount of 2,6-dimethylpyridine in the infrared spectrum could be calculated. After desorption at 250℃ for 1 hour, the sample was cooled to room temperature, and the spectrum was collected. The amount of weak acid with a desorption temperature of 2,6-dimethylpyridine <250℃ was calculated.
[0065] In this invention, the bulk SiO2 / Al2O3 (molar ratio) was obtained by X-ray fluorescence spectroscopy (XRF) analysis using a ZSX100e X-ray fluorescence spectrometer with Kα spectral line, LiF1 crystal, Rh target material, SC scintillation detector, timing of 20s, and vacuum atmosphere.
[0066] In this invention, the SiO2 / Al2O3 molar ratio on the outer surface was measured by X-ray photoelectron spectroscopy (XPS). The elemental composition and state of the catalyst surface were determined using a Thermofisher Multilab2000 electron spectrometer, with Mg Kα as the excitation source and a cathode voltage and current of 13 kV and 20 mA, respectively. The electron binding energy was calibrated using C1s (284.6 eV).
[0067] In this invention, the calculation formulas for the CO2 reaction rate and CO selectivity in the embodiments and comparative examples are as follows:
[0068] The reaction rate of CO2 (μmol / (g·s)) = (molar amount of carbon dioxide converted) / (mass of catalyst × reaction time);
[0069] CO selectivity (%) = (molar amount of CO generated / molar amount of carbon dioxide converted) × 100%.
[0070] Example 1: Preparation of ZSM-23 molecular sieve
[0071] 4.68 g of hexamethylenediamine was dissolved in 54 g of deionized water, and then 6 g of fumed silica was added. After stirring at room temperature (25°C) for 1 h, the mixture was transferred to a 100 mL reactor lined with polytetrafluoroethylene. The reactor was heated at 170°C for 24 h and then quenched. After centrifugation, 6 mL of oleylamine was added to the resulting solid. The mixture was thoroughly mixed in a shaker and stirred at room temperature (25°C) for 0.5 h at a stirring rate of 200 rpm. Then, 24 mL of 0.005 mol / L NaOH solution was added to the mixture, and the mixture was stirred at 25°C for 6 h at a stirring rate of 200 rpm to obtain mixture A. 0.24 g of ZSM-23 was added to deionized water, and 10 mL of ZSM-23 seed solution was added to mixture A. The mixture was stirred at 80°C for 16 h at a stirring rate of 200 rpm to obtain mixture B.
[0072] Add 0.17g Al2(SO4)3·18H2O and 0.40g pyrrolidine to 20mL of deionized water to obtain a clear solution C;
[0073] Solution C was added to mixture B and mixed thoroughly. The final mixture was then transferred to a 100 mL reactor lined with polytetrafluoroethylene and crystallized at 200 °C for 48 h. After crystallization, the mixture was filtered, washed, dried at 100 °C for 12 h, and then calcined at 550 °C for 4 h to obtain the final product, ZSM-23 molecular sieve. Analysis using pyridine adsorption infrared spectroscopy and 2,6-dimethylpyridine adsorption infrared spectroscopy revealed that the total Brønsted acid content of pyridine in ZSM-23 molecular sieve was 0.176 mmol / g, and the total Brønsted acid content of 2,6-dimethylpyridine was 0.160 mmol / g. The ratio of the total Brønsted acid content of 2,6-dimethylpyridine to the total Brønsted acid content of pyridine was 76:100. Among the Brønsted acid content of 2,6-dimethylpyridine in ZSM-23 molecular sieve, the amount of weak Brønsted acid below 250℃ was 0.126 mmol / g, and the ratio of the amount of weak Brønsted acid below 250℃ to the total Brønsted acid content of 2,6-dimethylpyridine was 79.0:100. The bulk SiO2 / Al2O3 molar ratio was 387, and the outer surface SiO2 / Al2O3 molar ratio was 71.
[0074] The XRD patterns of the prepared molecular sieves are shown in the figure. Figure 1 It is ZSM-23 molecular sieve.
[0075] Example 2: Preparation of ZSM-23 molecular sieve
[0076] 17.43 g of hexamethylenediamine was dissolved in 216 g of deionized water, and then 18 g of fumed silica was added. After stirring at room temperature (25°C) for 1 h, the mixture was transferred to a 300 mL reactor lined with polytetrafluoroethylene. The reactor was heated at 200°C for 12 h and then quenched. After centrifugation, 35 mL of oleylamine was added to the resulting solid. The mixture was thoroughly mixed in a shaker and stirred at room temperature (25°C) for 0.5 h at a stirring rate of 150 rpm. Then, 20 mL of 0.01 mol / L NaOH solution was added to the mixture, and the mixture was stirred at 25°C for 12 h at a stirring rate of 150 rpm to obtain mixture A. 0.9 g of ZSM-23 seed crystals were added to deionized water to prepare 30 mL of ZSM-23 seed crystal solution, which was then added to mixture A. The mixture was stirred at 100°C for 20 h at a stirring rate of 300 rpm to obtain mixture B.
[0077] Add 0.67g Al2(SO4)3·18H2O and 0.85g pyrrolidine to 20mL of deionized water to obtain a clear solution C;
[0078] Solution C was added to mixture B and mixed thoroughly. The final mixture was then transferred to a 150 mL reactor lined with polytetrafluoroethylene and crystallized at 200 °C for 36 h. After crystallization, the mixture was filtered, washed, dried at 100 °C for 12 h, and then calcined at 550 °C for 4 h to obtain the final product, ZSM-23 molecular sieve. Analysis using pyridine adsorption infrared spectroscopy and 2,6-dimethylpyridine adsorption infrared spectroscopy revealed that the total Brønsted acid content of pyridine in ZSM-23 molecular sieve was 0.176 mmol / g, and the total Brønsted acid content of 2,6-dimethylpyridine was 0.160 mmol / g. The ratio of the total Brønsted acid content of 2,6-dimethylpyridine to the total Brønsted acid content of pyridine was 91:100. Among the Brønsted acid content of 2,6-dimethylpyridine in ZSM-23 molecular sieve, the amount of weak Brønsted acid below 250℃ was 0.130 mmol / g, and the ratio of the amount of weak Brønsted acid below 250℃ to the total Brønsted acid content of 2,6-dimethylpyridine was 81.0:100. The bulk SiO2 / Al2O3 molar ratio was 246, and the outer surface SiO2 / Al2O3 molar ratio was 57.
[0079] The XRD patterns of the prepared molecular sieves are similar to those of... Figure 1 Similar to ZSM-23 molecular sieve.
[0080] Example 3: Preparation of ZSM-23 molecular sieve
[0081] 4.68 g of hexamethylenediamine was dissolved in 54 g of deionized water, and then 6 g of fumed silica was added. After stirring at room temperature (25°C) for 1 h, the mixture was transferred to a 100 mL reactor lined with polytetrafluoroethylene. The reactor was heated at 170°C for 24 h and then quenched. After centrifugation, 6 mL of oleylamine was added to the resulting solid. The mixture was thoroughly mixed in a shaker and stirred at room temperature (25°C) for 0.5 h at a stirring rate of 200 rpm. Then, 24 mL of 0.005 mol / L NaOH solution was added to the mixture, and the mixture was stirred at 25°C for 6 h at a stirring rate of 200 rpm to obtain mixture A. 0.24 g of ZSM-23 was added to deionized water, and 10 mL of ZSM-23 seed solution was added to mixture A. The mixture was stirred at 80°C for 16 h at a stirring rate of 200 rpm to obtain mixture B.
[0082] Add 0.17g Al2(SO4)3·18H2O and 0.40g pyrrolidine to 20mL of deionized water to obtain a clear solution C;
[0083] Solution C was added to mixture B and mixed thoroughly. The final mixture was then transferred to a 100 mL reactor lined with polytetrafluoroethylene and crystallized at 200 °C for 48 h. After crystallization, the mixture was filtered, washed, dried at 100 °C for 12 h, and then calcined at 550 °C for 4 h to obtain the final product, ZSM-23 molecular sieve. Analysis using pyridine adsorption infrared spectroscopy and 2,6-dimethylpyridine adsorption infrared spectroscopy revealed that the total Brønsted acid content of pyridine in ZSM-23 molecular sieve was 0.176 mmol / g, and the total Brønsted acid content of 2,6-dimethylpyridine was 0.160 mmol / g. The ratio of the total Brønsted acid content of 2,6-dimethylpyridine to the total Brønsted acid content of pyridine was 76:100. Among the Brønsted acid content of 2,6-dimethylpyridine in ZSM-23 molecular sieve, the amount of weak Brønsted acid below 250℃ was 0.126 mmol / g, and the ratio of the amount of weak Brønsted acid below 250℃ to the total Brønsted acid content of 2,6-dimethylpyridine was 79.0:100. The bulk SiO2 / Al2O3 molar ratio was 387, and the outer surface SiO2 / Al2O3 molar ratio was 71.
[0084] The XRD patterns of the prepared molecular sieves are similar to those of... Figure 1 Similar to ZSM-23 molecular sieve.
[0085] Example 4: Preparation of ZSM-23 molecular sieve
[0086] Measure 4.68g of hexamethylenediamine and dissolve it in 54g of deionized water. Then add 6g of fumed silica. Stir at room temperature (25℃) for 1h and transfer to a 100mL reactor with a polytetrafluoroethylene liner. Heat at 150℃ for 24h and then quench. After centrifugation, add 3mL of oleylamine to the resulting solid and mix thoroughly in a shaker. Stir at room temperature (25℃) for 0.5h at a stirring rate of 250rpm. Add 12mL of 0.08mol / L NaOH solution to the mixture and stir at 25℃ for 8h at a stirring rate of 250rpm to obtain mixture A. Add 0.18g of ZSM-23 seed crystals to deionized water to prepare 5mL of ZSM-23 seed crystal solution and add it to A. Stir at 60℃ for 30h at a stirring rate of 200rpm to obtain mixture B.
[0087] Add 0.44 g Al2(SO4)3·18H2O and 0.15 g pyrrolidine to 15 mL of deionized water to obtain a clear solution C;
[0088] Solution C was added to mixture B and mixed thoroughly. The final mixture was then transferred to a 100 mL reactor lined with polytetrafluoroethylene and crystallized at 180 °C for 24 h. After crystallization, the mixture was filtered, washed, dried at 100 °C for 12 h, and then calcined at 550 °C for 4 h to obtain the final product, ZSM-23 molecular sieve. Analysis using pyridine adsorption infrared spectroscopy and 2,6-dimethylpyridine adsorption infrared spectroscopy revealed that the total Brønsted acid content of pyridine in ZSM-23 molecular sieve was 0.123 mmol / g, and the total Brønsted acid content of 2,6-dimethylpyridine was 0.104 mmol / g. The ratio of the total Brønsted acid content of 2,6-dimethylpyridine to the total Brønsted acid content of pyridine was 85:100. Among the Brønsted acid content of 2,6-dimethylpyridine in ZSM-23 molecular sieve, the amount of weak Brønsted acid below 250℃ was 0.091 mmol / g, and the ratio of the amount of weak Brønsted acid below 250℃ to the total Brønsted acid content of 2,6-dimethylpyridine was 87.5:100. The bulk SiO2 / Al2O3 molar ratio was 137, and the outer surface SiO2 / Al2O3 molar ratio was 64.
[0089] The XRD patterns of the prepared molecular sieves are similar to those of... Figure 1 Similar to ZSM-23 molecular sieve.
[0090] Example 5: Preparation of Catalyst
[0091] Weigh 1g of copper nitrate and dissolve it in water according to the same volume of impregnation to prepare a solution. Then, add it dropwise to 10.2g of ZSM-23 molecular sieve prepared in Example 1 for impregnation. Let it stand overnight, and the next day put it in an oven. Set the temperature to 110℃ and the time to 6h. After drying, put the sample in a muffle furnace for calcination. The heating rate is 5℃ / min, the calcination temperature is 550℃, and the calcination time is 4h to obtain Cu / ZSM-23 sample.
[0092] 2.2 g of calcium chloride solid was weighed at room temperature and dissolved in water according to the equal volume impregnation amount. The solution was then mixed with the Cu / ZSM-23 sample using the equal volume impregnation method. After stirring evenly, the mixture was allowed to stand overnight. The sample was then placed in an oven at 110 °C for 8 hours. Subsequently, the dried precursor was calcined in a muffle furnace at a heating rate of 5 °C / min, a calcination temperature of 550 °C, and a calcination time of 4 hours to obtain the catalyst sample. The composition and content of the catalyst are shown in Table 1.
[0093] Example 6 Preparation of Catalyst
[0094] Weigh 0.71g of copper chloride and dissolve it in water according to the same volume of impregnation to prepare a solution. Then, add it dropwise to 10.2g of ZSM-23 molecular sieve prepared in Example 2 for impregnation. Let it stand overnight, and the next day put it in an oven. Set the temperature to 110℃ and the time to 6h. After drying, put the sample in a muffle furnace for calcination. The heating rate is 5℃ / min, the calcination temperature is 550℃, and the calcination time is 4 hours to obtain Cu / ZSM-23 sample.
[0095] 3.2 g of calcium bicarbonate solid was weighed at room temperature and dissolved in water according to the equal volume impregnation amount. The solution was then sonicated for 10 min at a frequency of 25 kHz. The solution was then mixed with the Cu / ZSM-23 sample using the equal volume impregnation method, stirred thoroughly, and allowed to stand overnight. The sample was then placed in an oven at 110 °C for 8 h. Subsequently, the dried precursor was calcined in a muffle furnace at a heating rate of 5 °C / min, a calcination temperature of 550 °C, and a calcination time of 4 h to obtain the catalyst sample. The composition and content of the catalyst are shown in Table 1.
[0096] Example 7 Preparation of Catalyst
[0097] Weigh 1.3g of copper nitrate and dissolve it in water according to the same volume of impregnation to prepare a solution. Then, add it dropwise to 10.2g of ZSM-23 molecular sieve prepared in Example 3 for impregnation. Let it stand overnight, and the next day put it in an oven. Set the temperature to 110℃ and the time to 6h. After drying, put the sample in a muffle furnace for calcination. The heating rate is 5℃ / min, the calcination temperature is 550℃, and the calcination time is 4 hours to obtain Cu / ZSM-23 sample.
[0098] 1.9 g of calcium chloride solid was weighed at room temperature and dissolved in water according to the equal volume impregnation amount. The solution was then mixed with the Cu / ZSM-23 sample using the equal volume impregnation method. After stirring evenly, the mixture was allowed to stand overnight. The sample was then placed in an oven at 110 °C for 8 hours. Subsequently, the dried precursor was calcined in a muffle furnace at a heating rate of 5 °C / min, a calcination temperature of 550 °C, and a calcination time of 4 hours to obtain the catalyst sample. The composition and content of the catalyst are shown in Table 1.
[0099] Example 8: Preparation of Catalyst
[0100] Weigh 1g of copper nitrate and dissolve it in water according to the same volume of impregnation to prepare a solution. Then, add it dropwise to 6.45g of ZSM-23 molecular sieve prepared in Example 4 for impregnation. Let it stand overnight, and the next day put it in an oven. Set the temperature to 110℃ and the time to 6h. After drying, put the sample in a muffle furnace for calcination. The heating rate is 5℃ / min, the calcination temperature is 550℃, and the calcination time is 4h to obtain Cu / ZSM-23 sample.
[0101] 2.2 g of calcium chloride solid was weighed at room temperature and dissolved in water according to the equal volume impregnation amount. The solution was then mixed with the Cu / ZSM-23 sample using the equal volume impregnation method. After stirring evenly, the mixture was allowed to stand overnight. The sample was then placed in an oven at 110 °C for 8 hours. Subsequently, the dried precursor was calcined in a muffle furnace at a heating rate of 5 °C / min, a calcination temperature of 550 °C, and a calcination time of 4 hours to obtain the catalyst sample. The composition and content of the catalyst are shown in Table 1.
[0102] Comparative Example 1
[0103] Weigh 1g of copper nitrate and dissolve it in water according to the same volume impregnation amount to prepare a solution. Then, add the solution dropwise to 10.2g of ZSM-23 molecular sieve prepared in Example 1 for impregnation. Let it stand overnight, and the next day place it in an oven at a set temperature of 110℃ for 6 hours. After drying, place the sample in a muffle furnace for calcination at a heating rate of 5℃ / min, a calcination temperature of 550℃, and a calcination time of 4 hours to obtain the catalyst sample. The composition and content of the catalyst are shown in Table 1.
[0104] Comparative Example 2
[0105] The catalyst was prepared using the same method as in Example 5, except that the ZSM-23 molecular sieve was replaced with the ZSM-5 molecular sieve.
[0106] The composition and content of the catalyst are shown in Table 1.
[0107] Comparative Example 3
[0108] Weigh 1g of copper nitrate and dissolve it in water according to the same volume of impregnation to prepare a solution. Then, add it dropwise to 10.2g of ZSM-23 molecular sieve prepared in Example 1 for impregnation. Let it stand overnight, and the next day put it in an oven. Set the temperature to 110℃ and the time to 6h. After drying, put the sample in a muffle furnace for calcination. The heating rate is 5℃ / min, the calcination temperature is 550℃, and the calcination time is 4h to obtain Cu / ZSM-23 sample.
[0109] 3.1 g of magnesium chloride solid was weighed at room temperature and dissolved in water according to the equal volume impregnation amount. The solution was then mixed with the Cu / ZSM-23 sample using the equal volume impregnation method. After stirring evenly, the mixture was left to stand overnight. The sample was then placed in an oven at 110°C for 8 hours. Subsequently, the dried precursor was calcined in a muffle furnace at a heating rate of 5°C / min, a calcination temperature of 550°C, and a calcination time of 4 hours to obtain the catalyst sample. The composition and content of the catalyst are shown in Table 1.
[0110] Comparative Example 4
[0111] The difference between this example and Example 1 lies in the preparation method of the ZSM-23 molecular sieve. This example uses the preparation method of Example 1 in patent CN109516471A to prepare the ZSM-23 molecular sieve, as detailed below:
[0112] (1) Preparation of ZSM-23 molecular sieve
[0113] 0.079 g NaOH, 0.163 g Al2(SO4)3·18H2O, 0.438 g pyrrolidine, and 1.48 g fumed silica were sequentially dissolved in 20.0 g deionized water and thoroughly mixed to obtain gel A. The molar ratio of each component was SiO2 in the silicon source: Al2O3 in the aluminum source: PY: NaOH: H2O = 1:0.01:0.25:0.083:45. Gel A was heated in a 180℃ constant temperature oven for 12 h and then cooled to room temperature. 0.119 g NaOH, 0.489 g... Al2(SO4)3·18H2O and 2.22 g of fumed silica were dissolved sequentially in 30.0 g of deionized water and stirred until homogeneous to obtain gel B. The molar ratio of the components was SiO2 (silicon source): Al2O3 (aluminum source): NaOH:H2O = 1:0.02:0.083:45. Gel B was added to gel A and mechanically stirred for 1 h to obtain a uniform white gel. This gel was transferred to a 100 mL hydrothermal reactor and crystallized at 180 °C for 44 h. The resulting product was then filtered, washed, and dried at 65 °C for 24 h to obtain ZSM-23 molecular sieve.
[0114] Analysis using pyridine adsorption infrared spectroscopy and 2,6-dimethylpyridine adsorption infrared spectroscopy revealed that the total Brønsted acid content of pyridine in HZSM-23 molecular sieve was 0.268 mmol / g, and the total Brønsted acid content of 2,6-dimethylpyridine was 0.155 mmol / g. The ratio of the total Brønsted acid content of 2,6-dimethylpyridine to the total Brønsted acid content of pyridine was 58:100. Among the Brønsted acid content of 2,6-dimethylpyridine in HZSM-23 molecular sieve, the amount of weak Brønsted acid below 250℃ was 0.078 mmol / g, and the ratio of the amount of weak Brønsted acid below 250℃ to the total Brønsted acid content of 2,6-dimethylpyridine was 50.4:100. The bulk SiO2 / Al2O3 molar ratio was 92, and the outer surface SiO2 / Al2O3 molar ratio was 86.
[0115] The catalyst preparation in this example is the same as in Example 5. The composition and content of the catalyst are shown in Table 1.
[0116] Comparative Example 5
[0117] Weigh 1g of copper nitrate and 2.2g of calcium chloride solid, dissolve them in water according to the equal volume impregnation amount, and then dropwise add them onto 10.2g of ZSM-23 molecular sieve prepared in Example 1 for impregnation. Let it stand overnight, then place the sample in an oven and set the temperature to 110℃ for 8 hours. Subsequently, place the dried precursor in a muffle furnace for calcination at a heating rate of 5℃ / min, a calcination temperature of 550℃, and a calcination time of 4 hours to obtain the catalyst sample.
[0118] The composition and content of the catalyst are shown in Table 1.
[0119] Catalytic performance test
[0120] The activity evaluation of the catalysts prepared in the above examples and comparative examples in the reaction of carbon dioxide hydrogenation to carbon monoxide was carried out in a micro fixed-bed reactor at atmospheric pressure. The reactor used for evaluation was a quartz tube with an inner diameter of 4 mm. The catalyst was pretreated before evaluation: it was first treated at 450°C for 2 h in a 20% H2 / N2 mixed atmosphere, and then cooled to room temperature. After pretreatment, the catalyst was heated to the required reaction temperature under N2 protection, and then the reaction gas was switched to (CO2:H2 = 1:2). The space velocity of the reactants was 300 L / g / h, the reaction temperature was 300°C, and the reaction time was 60 min. The reaction products were detected using online gas chromatography (TCD) (column TDX-01, H2 as carrier gas, and TCD detector). Quantitative analysis was performed using the internal standard method with N2 as the internal standard gas. The evaluation results are shown in Table 1.
[0121] The stability test conditions for the catalyst provided by this invention are the same as those for the catalyst performance test conditions described above, except that the test time is extended to 60 hours. The stability results of the catalyst prepared in Example 5 are shown below. Figure 2,from Figure 2 It can be seen that the catalyst's reactivity remained basically stable within 60 hours of the reaction.
[0122] Table 1. Composition and catalytic performance of the examples and comparative examples.
[0123]
[0124]
[0125] The specific embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A metal-modified molecular sieve, characterized in that, The metal-modified molecular sieve is Ca. b CuO x / ZSM-23 molecular sieve; Where b is 1.5 to 16, and x is the total number of oxygen atoms required to satisfy the oxidation states of each element in the metal oxide.
2. The metal-modified molecular sieve according to claim 1, characterized in that, In the metal-modified molecular sieve, based on the mass of the metal-modified molecular sieve, the mass content of calcium element is 2wt% to 8wt% (calculated as elemental calcium).
3. The metal-modified molecular sieve according to claim 1, characterized in that, The total Brønsted acid content of pyridine in infrared spectroscopy for the ZSM-23 molecular sieve is 0.10–0.37 mmol / g; the total Brønsted acid content of 2,6-dimethylpyridine in infrared spectroscopy is 0.07–0.35 mmol / g. And / or, the ratio of the total Brønsted acid content of 2,6-dimethylpyridine in infrared to the total Brønsted acid content of pyridine in infrared is (65-99):100; And / or, in the 2,6-dimethylpyridine infrared acid of the ZSM-23 molecular sieve, the amount of weak Brønsted acid with a desorption temperature <250℃ is 0.09 to 0.31 mmol / g; And / or, in the 2,6-dimethylpyridine infrared acid of the ZSM-23 molecular sieve, the ratio of the amount of weak Brønsted acid with a desorption temperature <250℃ to the amount of total Brønsted acid in the 2,6-dimethylpyridine infrared sieve is (64~95):
100. And / or, the bulk SiO2 / Al2O3 molar ratio of the ZSM-23 molecular sieve is 40-400 higher than the outer surface SiO2 / Al2O3 molar ratio; the bulk SiO2 / Al2O3 molar ratio of the ZSM-23 molecular sieve is 80-500, and the outer surface SiO2 / Al2O3 molar ratio is 40-120.
4. A method for preparing the metal-modified molecular sieve according to any one of claims 1-3, the method comprising: (a) A copper salt solution was impregnated onto ZSM-23 molecular sieve, and after standing and drying, a first calcination was performed to obtain a molecular sieve catalyst precursor. (b) The calcium salt is impregnated into the molecular sieve catalyst precursor, dried, and calcined a second time to obtain the metal-modified molecular sieve.
5. The preparation method according to claim 4, characterized in that, In step (a), the preparation method of the ZSM-23 molecular sieve includes the following steps: (1) Mix silicon source, template agent a and water, and carry out crystallization reaction after mixing. After the reaction, the material is separated into solid and liquid to obtain solid material. (2) Mix the solid material obtained in step (1) with aliphatic amines; (3) Add an alkaline source solution to the material obtained in step (2) and perform a first low-temperature treatment; then add ZSM-23 seed crystals and perform a second low-temperature treatment; (4) Prepare an aqueous solution containing template agent b and aluminum source, and then mix it with the material obtained in step (3) to obtain a gel. After crystallization, filtration, washing, drying and calcination, ZSM-23 molecular sieve is obtained.
6. The preparation method according to claim 5, characterized in that, In step (1), the template agent a is at least one of hexamethylenediamine, ethanol, and n-hexamethyleneamine; And / or, in step (1), the molar ratio of the template agent a to the silicon source (calculated as SiO2) is 0.1 to 1.0; the molar ratio of water to the silicon source (calculated as SiO2) is 20 to 80; And / or, in step (1), the operating conditions of the crystallization reaction are as follows: the crystallization temperature is 120 to 220°C, and the crystallization time is 8 to 48 hours.
7. The preparation method according to claim 5, characterized in that, In step (2), the fatty amine is one or more of oleylamine (9-octadeceneamine), octadecylamine, and dodecylamine; And / or, in step (2), the liquid-to-solid ratio of the fatty amine to the solid material obtained in step (1) is 0.3 to 3 mL / g.
8. The preparation method according to claim 5, characterized in that, In step (3), the alkaline source used in the alkaline source solution is any one of sodium hydroxide, potassium hydroxide and ammonia water, and the concentration of the alkaline source solution is 0.003 to 0.015 mol / L; the liquid-solid ratio of the alkaline source solution to the solid material obtained in step (1) is 2 to 20 mL / g. And / or, in step (3), the temperature of the first low-temperature treatment is 20-40°C and the time is 3-15 hours; And / or, in step (3), the ZSM-23 seed crystals are added in the form of seed crystal solution. The specific operation process of the seed crystal solution is as follows: the ZSM-23 seed crystals are uniformly dispersed in water to form seed crystal solution; wherein, the liquid-solid ratio of water to ZSM-23 seed crystals is 5 to 70 mL / g. And / or, in step (3), based on the weight of the solid material obtained in step (1), the amount of ZSM-23 seed crystals added is 0.1 to 8.0 wt%. And / or, in step (3), the second low-temperature treatment is performed at a temperature of 60 to 120°C for a time of 6 to 30 hours.
9. The preparation method according to claim 5, characterized in that, In step (4), the template agent b is one or more of pyrrolidine, isopropylamine and N,N-dimethylformamide; the aluminum source is one or more of aluminum sulfate, aluminum isopropoxide, sodium aluminate and aluminum hydroxide. And / or, in step (4), the aluminum source is calculated as Al2O3, and the solid material obtained in step (1) is calculated as SiO2, wherein the molar ratio of template agent b to the solid material obtained in step (1) is 0.01 to 0.1; the molar ratio of aluminum source to the solid material obtained in step (1) is 0.002 to 0.015; the water in the aqueous solution containing template agent b and aluminum source has a molar ratio of 300 to 3000 to aluminum source, preferably 400 to 2000; And / or, in step (4), the crystallization temperature is 180-220℃, the crystallization time is 24-72h; the drying temperature is 80-120℃, the drying time is 6-12h; the calcination temperature is 540-560℃, and the calcination time is 3-8h.
10. The preparation method according to claim 4, characterized in that, In step (a), the copper salt is selected from at least one of copper nitrate and copper chloride; And / or, in step (a), the first calcination is carried out by programmed temperature rise calcination, with a temperature rise rate of 2 to 10 °C / min, a calcination temperature of 450 to 650 °C, and a calcination time of 4 to 10 h.
11. The preparation method according to claim 4, characterized in that, In step (b), the calcium salt is selected from at least one of calcium chloride and calcium bicarbonate; And / or, in step (b), the mass ratio of copper salt, ZSM-23 molecular sieve, and calcium salt is 1:(5-20):(1-8); And / or, in (b), the second calcination is carried out by programmed temperature rise calcination, with a heating rate of 2 to 10 °C / min, a calcination temperature of 500 to 650 °C, and a calcination time of 4 to 10 h.
12. The application of the metal-modified molecular sieve according to any one of claims 1-3 or the metal-modified molecular sieve obtained by the preparation method according to any one of claims 4-11 in the reaction of carbon dioxide hydrogenation to carbon monoxide.
13. The application according to claim 12, characterized in that, The reaction of carbon dioxide hydrogenation to produce carbon monoxide uses carbon dioxide and hydrogen as reaction gases; in the reaction, the volume ratio of carbon dioxide to hydrogen is 1:(1-4).
14. The application according to claim 12, characterized in that, The reaction temperature is 200–600℃, preferably 250–500℃, the reaction time is 30–60 min, and the space velocity of carbon dioxide and hydrogen is 36–600 L / g / h.