Catalyst, process for its preparation and use, and process for the methanecarbon dioxide reforming reaction

Abstract

The application relates to the technical field of catalysts, and discloses a catalyst, a preparation method and application thereof, and a method for methane carbon dioxide reforming reaction, the catalyst comprising an active substrate and CeO2, wherein the active substrate comprises La-Ni-based oxides with a perovskite structure; the catalyst has diffraction peaks at 2theta of 32.7+ / -0.3 degrees, 31.3+ / -0.3 degrees and 28.0+ / -0.3 degrees as measured by X-ray diffraction; and the catalyst has at least one reduction peak below 400 DEG C as measured by H2-TPR. The catalyst has high activity and stability, can effectively enhance CO2 adsorption during the reaction, reduce CH4 adsorption and cracking, and has good carbon deposition resistance.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a catalyst, its preparation method and application, and a method for methane-carbon dioxide reforming reaction. Background Technology

[0002] Methane and carbon dioxide are both greenhouse gases. Methane-carbon dioxide reforming to produce syngas is an effective way to utilize CO2 on a large scale, while also utilizing relatively inexpensive natural gas to generate syngas (CO + H2). The syngas can be further converted into other high-value-added downstream hydrocarbon products. However, the biggest problem with this reaction process is that the catalysts used in methane-carbon dioxide reforming to produce syngas are mainly nickel-based catalysts, which are prone to carbon deposition. If this carbon deposition problem cannot be effectively solved, it will severely limit the stability of the catalyst and the industrialization process.

[0003] Perovskites have become a focus of attention in many fields due to their excellent electrical conductivity, magnetism, thermoelectricity, piezoelectricity, and other properties, as well as their low preparation cost and thermodynamic and mechanical stability at high temperatures. Perovskite composite oxide materials are excellent conductors of oxygen ions and electrons under high-temperature conditions, and can release oxygen even under inert conditions. Furthermore, oxygen can be replenished through the Redox process. Therefore, using perovskite oxides as catalysts for methane-carbon dioxide reforming can effectively eliminate carbon deposits on the catalyst surface, thus improving the catalyst's resistance to carbon deposition. However, the catalyst's activity and resistance to carbon deposition are still not entirely ideal.

[0004] CN113600200A discloses a method for preparing a Ni-based alkaline earth metal modified catalyst for methane dry reforming that resists carbon deposition. First, an alkaline earth metal-doped LaAl perovskite support is prepared, and then Ni is loaded onto the support via an impregnation method. However, the catalyst's stability remains unsatisfactory. CN114588912A discloses a method for preparing a perovskite-type catalyst suitable for methane dry reforming, which involves doping LaNiO3 perovskite at the A-site with alkali metal K ions to form La... x K 1-x NiO3 is used as a base, with the addition of structurally stable CeO2 solid powder, which has a high oxygen capacity. CN114471581A discloses a coking-resistant methane-carbon dioxide reforming catalyst, in which Ce is supported on the surface of perovskite oxide to obtain a Ce-supported ABO3-type perovskite oxide catalyst. All of the above methods utilize the oxygen storage capacity of CeO2 to rapidly eliminate coking on the catalyst surface during the methane-carbon dioxide reforming reaction; however, the high CeO2 loading is not conducive to improving catalyst activity. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of insufficient activity, poor stability, and poor anti-coking performance of existing methane-carbon dioxide reforming catalysts, and to provide a catalyst, its preparation method and application, and a method for methane-carbon dioxide reforming reaction. This catalyst has good anti-coking performance and high activity and stability.

[0006] To achieve the above objectives, the first aspect of the present invention provides a catalyst comprising an active matrix and CeO2, wherein the active matrix comprises a La-Ni-based oxide having a perovskite structure; X-ray diffraction analysis revealed that the catalyst exhibits diffraction peaks at 2θ of 32.7±0.3°, 31.3±0.3°, and 28.0±0.3°.

[0007] H2-TPR analysis showed that the catalyst exhibited at least one reduction peak below 400 °C.

[0008] Preferably, the CeO2 content is 1-6 wt%, more preferably 2-4 wt%, based on the total amount of the catalyst.

[0009] A second aspect of the present invention provides a method for preparing a catalyst, comprising the following steps:

[0010] (1) In the presence of a complexing agent, La source and Ni source are mixed to obtain a mixture;

[0011] (2) The mixture is reacted to form a gel, and then subjected to a first calcination to obtain a semi-finished catalyst;

[0012] (3) In the presence of a surfactant, a solution of a soluble compound containing Ce is contacted with the semi-finished catalyst, and then a second calcination is performed;

[0013] The surfactants include polyoxyethylene nonionic surfactants and polyol nonionic surfactants.

[0014] The third aspect of this invention provides the application of the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect in the methane-carbon dioxide reforming reaction.

[0015] A fourth aspect of the present invention provides a method for a methane-carbon dioxide reforming reaction, comprising: contacting methane and carbon dioxide with a catalyst under reforming reaction conditions, wherein the catalyst is the catalyst described in the first aspect or a catalyst prepared by the preparation method described in the second aspect.

[0016] The catalyst provided by this invention has high activity and stability, can effectively enhance CO2 adsorption, reduce CH4 adsorption and cracking during the reaction process, and has good anti-carbon deposition performance. Attached Figure Description

[0017] Figure 1 These are the XRD patterns of the catalysts prepared in Examples 1, 2, 3, and 4 of this invention, as well as Comparative Examples 6 and 7.

[0018] Figure 2 These are the crystal phase analysis spectra of the catalysts prepared in Example 1 and Comparative Example 1 of this invention;

[0019] Figure 3 These are the H2-TPR curves of the catalysts prepared in Examples 1, 2, 3, 4, 6 and Comparative Example 6 of this invention;

[0020] Figure 4 These are the H2-TPR curves of the catalysts prepared in Example 1 and Comparative Example 8 of this invention;

[0021] Figure 5 These are the stability evaluation results of the catalysts prepared in Examples 1 and 6 and Comparative Example 1 of this invention;

[0022] Figure 6 This is a thermogravimetric analysis diagram of the catalysts prepared in Examples 1, 6 and Comparative Example 6 of this invention after reacting for 100 hours. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] The first aspect of the present invention provides a catalyst comprising an active matrix and CeO2, wherein the active matrix comprises a La-Ni-based oxide having a perovskite structure; X-ray diffraction shows that the catalyst has diffraction peaks at 2θ of 32.7±0.3°, 31.3±0.3°, and 28.0±0.3°; H2-TPR shows that the catalyst has at least one reduction peak below 400°C.

[0025] In this invention, the term "perovskite structure" has a broad definition, referring to a crystal structure that is the same as or similar to that of perovskite CaTiO3. "La-Ni-based oxides having a perovskite structure" refers to compounds containing Li, Ni, and O elements and having a crystal structure that is the same as or similar to that of perovskite CaTiO3, and may include LaNiO3 and / or La2NiO4.

[0026] In existing technologies, research on perovskite catalysts is usually limited to elemental doping or loading, with a lack of research on the special structures of perovskite composite oxide materials. The catalyst provided by this invention possesses a unique composite perovskite structure. X-ray diffraction (XRD) analysis revealed diffraction peaks at 32.7±0.3°, 31.3±0.3°, and 28.0±0.3°. JCPDS standard card fitting analysis identified the diffraction peak at 32.7±0.3° as belonging to the perovskite-structured LaNiO3 species, the peak at 31.3±0.3° as belonging to the perovskite-like La2NiO4 species, and the peak at 28.0±0.3° as belonging to the CeO2 species.

[0027] In this invention, X-ray diffraction (XRD) tests are performed on an X'Pert3 Powder diffractometer using a Cu Kα target line (incident wavelength). The scanning range is 0-90°, and the scanning speed is 10° / min.

[0028] In this invention, the statement "the catalyst has at least one reduction peak below 400°C" means that the reduction temperature corresponding to the peak of the reduction peak in the H2-TPR curve is below 400°C. Similarly, the following description of reduction temperature refers to the temperature corresponding to the peak of the reduction peak in the H2-TPR curve.

[0029] In the prior art, Ni-based catalysts have high reduction temperatures; the reduction temperatures of previously reported Ni-based perovskite composite oxides are typically above 400°C. In this invention, H₂-TPR analysis shows that the catalyst exhibits at least one reduction peak below 400°C. Preferably, H₂-TPR analysis shows at least one reduction peak between 350-390°C. More preferably, the catalyst exhibits at least two reduction peaks between 350-390°C. For example, one reduction peak may exist between 350-370°C, and another between 380-390°C.

[0030] In this invention, the test conditions for H2-TPR include:

[0031] The reduction behavior of the catalyst was tested using a TP-5080 adsorption analyzer. First, 30 mg of sample was placed in a quartz tube, and N2 was introduced at a flow rate of 30 mL / min. The temperature was increased to 150 °C at a rate of 10 °C / min in the N2 atmosphere and held for 30 min, then cooled to room temperature. The gas atmosphere was then switched to 5 vol% H2-95 vol% N2, and the temperature was increased to 900 °C at a rate of 10 °C / min to obtain the H2-TPR curve. The exhaust gas was detected using a TCD.

[0032] In this invention, the catalyst exhibits a low reduction temperature, high activity, and high stability. This is likely due to the interfacial effect formed by CeO2 dispersed on the surface of the La-Ni-based oxide. Under the synergistic effect of CeO2, the unique spatial structure of LaNiO3 (with its infinite perovskite layers) and La2NiO4 (with its alternating rock salt and perovskite layers) further facilitates Ni reduction, significantly lowering the catalyst's reduction temperature and consequently reducing the average particle size of the reduced Ni particles. Simultaneously, this interfacial structure significantly enhances the catalyst's internal electron transfer and oxygen vacancy transport capabilities during the reaction, improving its ability to inhibit coking and convert existing coke deposits, thereby enhancing the catalyst's activity and stability.

[0033] According to the present invention, preferably, the Ni element in the La-Ni-based oxide having a perovskite structure includes divalent nickel and trivalent nickel. It is understood that the divalent nickel can be a Ni species in the La2NiO4 structure, and the trivalent nickel can be a Ni species in the LaNiO3 structure.

[0034] In a further preferred embodiment, XPS characterization shows that the molar ratio of Ni to La in the catalyst is (1.5-2.5):1, preferably (1.8-2.2):1.

[0035] In this invention, elemental valence states and surface elemental contents were determined by XPS. XPS characterization was performed on an AXIS-ULTRADLD X-ray photoelectron spectrometer using a monochromatic Al-Kα target source, and at a resolution of 1×10⁻⁶. -8 Vacuum was applied under Pa conditions. To subtract the charge effect, the C1s peak of contaminated carbon (binding energy of 284.6 eV) was used as the calibration standard.

[0036] According to some preferred embodiments of the present invention, after the catalyst is reduced at 450°C for 2 hours in a hydrogen atmosphere, the average particle size of Ni, as measured by XRD, is 13-22 nm, preferably 15-18 nm. In the prior art, the average particle size of Ni particles after reduction by Ni-based perovskite catalysts is typically 30-45 nm. The catalyst provided by the present invention has a smaller grain size after reduction.

[0037] In this invention, the method for measuring the average particle size of Ni specifically includes: determining the average particle size of Ni at 2θ = 44.5° using XRD characterization. 0 The diffraction angles and full width at half maximum (FWHM) of the phases were determined, and then the grain size of the active centers was measured using the Scherrer equation.

[0038] In existing technologies, the introduction of CeO2 into catalysts primarily utilizes its oxygen storage properties to facilitate the elimination of carbon deposits on the catalyst surface during the reaction. However, achieving this objective requires a high CeO2 content, typically above 10 wt%. In this invention, CeO2 is introduced to form an interfacial effect, and its content does not need to be excessively high. Preferably, based on the total amount of the catalyst, the CeO2 content is 1-6 wt%, more preferably 2-4 wt%. In this preferred configuration, the amount of CeO2 that forms the maximum interfacial layer between the CeO2 and the perovskite matrix is ​​maximized. Insufficient CeO2 content results in less contact area between the CeO2 and the perovskite matrix, while excessive CeO2 will cover most of the perovskite matrix surface, reducing the exposed interfacial area and decreasing activity.

[0039] The composition of the catalyst was analyzed by X-ray fluorescence spectroscopy (XRF, EAGLE III, EDAX Inc.). The elemental composition and content of each element were analyzed by performing a full elemental scan of the catalyst.

[0040] In a further preferred embodiment, XPS characterization shows that the molar ratio of Ni to Ce in the catalyst is (1-20):1, preferably (2-15):1.

[0041] According to a preferred embodiment of the present invention, the active matrix further includes an auxiliary element selected from at least one alkaline earth metal, preferably at least one selected from Mg, Ca, and Sr, and more preferably Mg. In the above-mentioned preferred embodiment, it is beneficial to further improve the catalyst's resistance to carbon deposition and its stability.

[0042] According to the present invention, preferably, the content of the auxiliary element, calculated as oxide, is 1-5 wt% based on the total mass of the active matrix, and more preferably 1.5-3 wt%.

[0043] According to a preferred embodiment of the present invention, the active matrix further includes a molecular sieve. The regular pore structure of the molecular sieve and the well-developed surface organic groups (such as hydroxyl groups) within the pores interact with the perovskite, which is beneficial for further improving the catalyst's resistance to carbon deposition and for further limiting the average particle size of Ni.

[0044] Preferably, the molecular sieve content, calculated as silica, is 5-15 wt% based on the total mass of the active matrix, and more preferably 9-11 wt%.

[0045] In this invention, the presence of the molecular sieve can be proven by crystal phase analysis, and its content is characterized by XRF.

[0046] The crystal phase analysis of the samples was performed using a Philips PW1710 X-ray diffractometer with a Cu target, Kα radiation source, tube voltage of 40 kV, tube current of 30 mA, scanning step size of 0.02°, scanning speed of 1.2° / min, and scanning range of 2θ = 1-10°.

[0047] In a further preferred embodiment, the molecular sieve is a fully silica mesoporous molecular sieve with a regular pore structure, preferably at least one of MCM-41, SBA-15, MCM-48 and SBA-16 molecular sieves, and more preferably MCM-41 molecular sieve.

[0048] In some particularly preferred embodiments of the present invention, the catalyst comprises an active matrix and CeO2, wherein the active matrix comprises a La-Ni-based oxide having a perovskite structure, an auxiliary element, and a molecular sieve; X-ray diffraction analysis revealed that the catalyst exhibits diffraction peaks at 2θ of 32.7±0.3°, 31.3±0.3°, and 28.0±0.3°;

[0049] H2-TPR analysis showed that the catalyst exhibited at least one reduction peak below 400 °C.

[0050] The selection range and content of the auxiliary elements and molecular sieves are the same as those provided above, and will not be repeated here.

[0051] A second aspect of the present invention provides a method for preparing a catalyst, comprising the following steps:

[0052] (1) In the presence of a complexing agent, a La source, a Ni source and a solvent are mixed to obtain a mixture;

[0053] (2) The mixture is reacted to form a gel, and then subjected to a first calcination to obtain a semi-finished catalyst;

[0054] (3) In the presence of a surfactant, a solution of a soluble compound containing Ce is contacted with the semi-finished catalyst, and then a second calcination is performed;

[0055] The surfactants include polyoxyethylene nonionic surfactants and polyol nonionic surfactants.

[0056] According to some preferred embodiments of the present invention, in step (1), the molar ratio of the Ni source to the La source, based on metal elements, is (0.5-2):1, preferably (0.5-1.5):1.

[0057] Preferably, the total molar amount of the La source and Ni source, calculated as metal elements, to the molar ratio of the complexing agent is 0.5-3:1, more preferably 1-2:1.

[0058] In this invention, the selection range for the specific types of La and Ni sources is relatively wide. Soluble organic or inorganic salts of metals can be used in this invention, for example, at least one of metal nitrates, acetates and oxalates.

[0059] The La and Ni sources may also contain water of crystallization, as is well known to those skilled in the art.

[0060] In this invention, the selection range of the complexing agent is relatively wide; any complexing agent capable of complexing La-source and Ni-source compounds in the art can be used in this invention. Preferably, the complexing agent is selected from citric acid and / or ethylenediaminetetraacetic acid.

[0061] According to some preferred embodiments of the present invention, the mixing method may be to first dissolve the complexing agent in a solvent, and then mix it with the La source and Ni source. The mixing in step (1) can be carried out under stirring conditions. The present invention does not particularly limit the specific stirring conditions, as long as the components can be fully mixed. Preferably, the mixing temperature is 50-100°C.

[0062] The present invention allows for a wide range of solvent choices in step (1), and preferably, the solvent is water. The present invention also does not impose any particular limitation on the amount of solvent used, as long as the components are sufficiently dispersed and mixed.

[0063] According to a preferred embodiment of the present invention, in step (1), the mixture further includes an auxiliary element precursor, wherein the auxiliary element is at least one of alkaline earth metals, preferably selected from at least one of Mg, Ca and Sr, and more preferably Mg.

[0064] Preferably, the amount of the auxiliary element precursor is such that the content of the auxiliary element, calculated as oxide, in the obtained semi-finished catalyst is 1-5 wt%, preferably 1.5-3 wt%.

[0065] According to some preferred embodiments of the present invention, the precursor of the auxiliary element may be an oxide of the auxiliary element or any substance that can form its oxide by calcination, such as at least one of nitrate, acetate and oxalate containing the auxiliary element.

[0066] According to some preferred embodiments of the present invention, in step (1), the mixture further includes a molecular sieve. The mixing method may be to first dissolve the complexing agent in a solvent, and then mix it with a La source, a Ni source, an optional auxiliary element precursor, and an optional molecular sieve.

[0067] Preferably, the amount of molecular sieve used is such that the content of the molecular sieve in the obtained semi-finished catalyst, calculated as silica, is 5-15 wt%, preferably 9-11 wt%.

[0068] The molecular sieve described herein has the same selection range as that described in the first aspect of this invention, and will not be repeated here.

[0069] Preferably, the molecular sieve has an average pore size of 1-15 nm, more preferably 5-10 nm. Using a molecular sieve with the above-mentioned preferred pore structure helps to better control the crystallite size of the catalyst and prevent aggregation.

[0070] According to some preferred embodiments of the present invention, in step (2), the reaction conditions include: a temperature of 50-100°C, preferably 60-90°C, and a time of 1-12h, preferably 6-8h.

[0071] Preferably, the conditions for the first calcination include: a temperature of 300-1200℃, more preferably 400-600℃, and a time of 2-20 hours, more preferably 4-8 hours. Optional drying may also be included before the first calcination. The present invention does not particularly limit the drying conditions, as long as the solvent can be removed. Preferably, the drying temperature is 80-120℃.

[0072] In this invention, the synergistic effect of polyoxyethylene nonionic surfactants and polyol nonionic surfactants facilitates the formation of interfacial effects between CeO2 / La-Ni-based oxides, thereby helping to reduce the reduction temperature of the catalyst and improve its activity and stability.

[0073] According to some preferred embodiments of the present invention, the polyoxyethylene nonionic surfactant is selected from polyethylene glycol and / or fatty alcohol polyoxyethylene ether, preferably at least one of PEG200, PEG400, PEG600, AEO-7, AEO-8 and AEO-9, more preferably at least one of PEG200, PEG400 and PEG600, and even more preferably PEG400.

[0074] According to some preferred embodiments of the present invention, the polyol nonionic surfactant is a sorbitan fatty acid ester, preferably at least one of sorbitan monopalmitate (Span 40), sorbitan monooleate (Span 80) and sorbitan monostearate (Span 60), more preferably sorbitan monooleate (Span 80).

[0075] In a further preferred embodiment, the mass ratio of the polyoxyethylene nonionic surfactant to the polyol nonionic surfactant is 1:(0.1-1), preferably 1:(0.1-0.5), and more preferably 1:(0.1-0.2). Under these preferred conditions, CeO2 is better dispersed on the catalyst surface, thus optimizing the interfacial effect.

[0076] In this invention, the objective of the invention can be achieved as long as the contact described in step (3) is carried out in the presence of the surfactant. According to some preferred embodiments of the invention, the mass ratio of the soluble Ce compound (calculated as CeO2) to the surfactant is 1:(1-10), preferably 1:(1-8). In the above preferred cases, it is advantageous to further improve the activity and stability of the catalyst.

[0077] The present invention does not particularly limit the method of introducing the surfactant. The surfactant can be prepared into a solution together with a Ce-soluble compound and then contacted with the semi-finished catalyst; or the surfactant can be introduced by contacting a solution containing a Ce-soluble compound with the semi-finished catalyst.

[0078] In this invention, the range of soluble compounds for Ce is relatively wide, as long as Ce element can be provided. Preferably, the soluble compounds for Ce are selected from at least one of cerium nitrate, cerium acetate, and cerium oxalate.

[0079] According to the present invention, the solvent in the solution of the Ce-containing soluble compound can be selected from conventional organic solvents in the art, preferably at least one of alcohols, ketones or hydrocarbons, more preferably at least one of methanol, ethanol, acetone and petroleum ether, and more preferably ethanol and / or methanol.

[0080] The present invention does not have a particular limitation on the amount of solvent used, as long as it is sufficient to dissolve the Ce-soluble compound. Preferably, the mass ratio of the Ce-soluble compound (calculated as oxide) to the solvent is 1:(1-50), more preferably 1:(10-30).

[0081] In some preferred embodiments of the present invention, the conditions for the second calcination include: a calcination temperature of 400-600°C and a constant temperature time of 2-6 hours.

[0082] Preferably, the second calcination method includes: first heating to 100-150°C at a heating rate of 3-6°C / min, then heating to 200-250°C at a heating rate of 0.2-0.6°C / min, and then heating to the calcination temperature at a heating rate of 3-6°C / min for constant temperature.

[0083] In this invention, a second drying process may be included before the second calcination, wherein the conditions for the second drying include a temperature of 80-120°C and a time of 8-48 hours.

[0084] In this invention, preferably, the product contacted in step (3) is directly subjected to a second calcination (if it also includes a second drying, then the second drying and second calcination are directly performed).

[0085] The third aspect of this invention provides the application of the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect in the methane-carbon dioxide reforming reaction.

[0086] A fourth aspect of the present invention provides a method for a methane-carbon dioxide reforming reaction, comprising: contacting methane and carbon dioxide with a catalyst under reforming reaction conditions, wherein the catalyst is the catalyst described in the first aspect or a catalyst prepared by the preparation method described in the second aspect.

[0087] According to some preferred embodiments of the present invention, the reforming reaction conditions include: a molar ratio of methane to carbon dioxide of 1:1-2, preferably 1:1.2-1.5; a reaction temperature of 700-950℃, preferably 750-850℃, more preferably 780-800℃; a pressure of 0.1-1 MPa, preferably 0.1-0.5 MPa, more preferably 0.2-0.4 MPa; and a total space velocity of the feed gas of 10000-30000 h⁻¹. -1 Preferably 15000-25000h -1 More preferably 18000-22000h -1 .

[0088] According to some preferred embodiments of the present invention, the method further includes: reducing the catalyst in a hydrogen atmosphere prior to the contact.

[0089] Preferably, the reduction conditions include: a temperature of 400-600℃, more preferably 400-550℃; a time of 1-20h, more preferably 2-6h; and a pressure of 0.1-0.5MPa, more preferably 0.2-0.3MPa.

[0090] The present invention will be described in detail below through embodiments.

[0091] Unless otherwise specified, all raw materials used in the following embodiments are commercially available.

[0092] The MCM-41 molecular sieve used in the following examples is an all-silica molecular sieve with an average pore size of 6 nm.

[0093] X-ray diffraction (XRD) tests were performed on an X'Pert3 Powder diffractometer using a Cu Kα target line (incident wavelength). The scanning range is 0-90°, and the scanning speed is 10° / min.

[0094] The crystal phase analysis of the samples was performed using a Philips PW1710 X-ray diffractometer with a Cu target, Kα radiation source, tube voltage of 40 kV, tube current of 30 mA, scanning step size of 0.02°, scanning speed of 1.2° / min, and scanning range of 2θ = 1-10°.

[0095] The H2-TPR test was performed using a TP-5080 adsorption instrument. First, 30 mg of sample was placed in a quartz tube, and N2 was introduced at a flow rate of 30 mL / min. The temperature was increased to 150 °C at a rate of 10 °C / min in the N2 atmosphere and held for 30 min, then cooled to room temperature. The gas atmosphere was then switched to 5% H2-95% N2, and the temperature was increased to 900 °C at a rate of 10 °C / min. The exhaust gas was detected using a TCD. The reducibility of the sample was determined by the amount of hydrogen consumed in the in-situ reduction of CuO.

[0096] The composition of the catalyst was analyzed by X-ray fluorescence spectroscopy (XRF, EAGLE III, EDAX Inc.). The elemental composition and content of each element were analyzed by performing a full elemental scan of the catalyst.

[0097] The method for determining the average particle size of Ni was as follows: The catalyst was reduced at 450°C for 2 hours under a hydrogen atmosphere, followed by XRD analysis on an X'Pert3 Powder diffractometer using a Cu Kα target line (incident wavelength). The scanning range is 0-90° and the scanning speed is 10° / min. The result is obtained by calculating using the Scherrer formula.

[0098] The catalyst carbon deposition content after the reaction was characterized by TGA. Thermal analysis was performed on a Perkin Elmer thermogravimetric analyzer (SETSYS Evolution, SETARAM) coupled with mass spectrometry (Hider, England) at a heating rate of 10 °C / min. -1 The test was conducted in an air atmosphere at a gas flow rate of 30 mL / min. -1 The measurement temperature range is from room temperature to 900℃.

[0099] Example 1

[0100] 68.8 g of citric acid was dissolved in 258 mL of water and stirred at 80 °C for 30 min until completely dissolved. 155 g of La(NO3)3·6H2O and 104 g of Ni(NO3)2·6H2O were added to the citric acid solution, and the mixture was stirred at 80 °C for 1 h. Then, 2 g of MgO and 10 g of commercially available MCM-41 molecular sieve were added to the solution, and the mixture was stirred at 80 °C for 8 h to form a gel. The gel was then dried at 110 °C and calcined at 650 °C for 6 h at a calcination rate of 5 °C / min. A semi-finished catalyst was obtained. The composition of the semi-finished catalyst was determined by XRF, as shown in Table 1.

[0101] Then, 40g of ethanol, 4g of PEG400, and 0.4g of Span80 were mixed. 8.4g of Ce(NO3)3·6H2O was dissolved in the above mixed solution. Then, 80g of catalyst semi-finished solid was impregnated with the solution containing Ce(NO3)3·6H2O for 8h. After impregnation, it was directly placed in an oven at 100℃ for drying, and then placed in a muffle furnace for calcination. The muffle furnace heating method was as follows: 50℃-120℃ with a heating rate of 5℃ / min, 120℃-220℃ with a heating rate of 0.5℃ / min, and 220-450℃ with a heating rate of 5℃ / min. Then, it was calcined at 450℃ for 4h to obtain catalyst CAT-1.

[0102] The composition of the catalyst is shown in Table 1.

[0103] The above catalyst was subjected to X-ray diffraction (XRD) testing, and the XRD pattern is shown below. Figure 1 As shown, the catalyst exhibits diffraction peaks at 2θ of 28.0°, 31.2°, and 32.7°, proving that the catalyst contains perovskite LaNiO3 and perovskite-like La2NiO4 structures, as well as CeO2.

[0104] The crystal phase analysis results of the sample are as follows Figure 2 As shown, the catalyst exhibits a distinct characteristic peak of MCM-41, proving the presence of MCM-41 molecular sieve.

[0105] The above catalyst was subjected to H2-TPR testing, and the results are as follows: Figure 3 and Figure 4 As shown, the catalyst exhibits two reduction peaks at 354 and 385 °C.

[0106] Example 2

[0107] Dissolve 68.8 g of citric acid in 258 mL of water and stir at 80 °C for 30 min until the citric acid is completely dissolved. Add 158 g of La(NO3)3·6H2O and 106 g of Ni(NO3)2·6H2O to the above citric acid aqueous solution and stir at 80 °C for 1 h. Add 1 g of MgO and 9 g of commercially available MCM-41 molecular sieve to the above solution and stir at 80 °C for 8 h to form a gel. Then dry the gel at 110 °C and calcine it at 650 °C for 6 h at a calcination rate of 5 °C / min. Obtain the catalyst semi-finished solid. 10g of ethanol, 1.9g of PEG200, and 0.3g of Span60 were mixed. 2g of Ce(NO3)3·6H2O was dissolved in the mixed solution. 80g of the catalyst semi-finished product was then impregnated with the Ce(NO3)3·6H2O solution for 8 hours. After impregnation, the product was directly placed in an oven at 120℃ for drying, and then placed in a muffle furnace for calcination. The muffle furnace heating method was as follows: 50℃-120℃ at a heating rate of 5℃ / min, 120℃-220℃ at a heating rate of 0.5℃ / min, and 220-450℃ at a heating rate of 5℃ / min. The product was then calcined at 450℃ for 4 hours to obtain catalyst CAT-2.

[0108] The composition of the catalyst is shown in Table 1.

[0109] The above catalyst was subjected to X-ray diffraction (XRD) testing, and the XRD pattern is shown below. Figure 1 As shown, the catalyst exhibits diffraction peaks at 2θ of 28.1°, 31.4°, and 32.9°, proving that the catalyst contains perovskite LaNiO3 and perovskite-like La2NiO4 structures, as well as CeO2.

[0110] The above catalyst was subjected to H2-TPR testing, and the results are as follows: Figure 3 As shown, the catalyst exhibits two reduction peaks at 354 °C and 389 °C.

[0111] Example 3

[0112] Dissolve 68.8 g of citric acid in 258 mL of water and stir at 80 °C for 30 min until the citric acid is completely dissolved. Add 151.4 g of La(NO3)3·6H2O and 101.7 g of Ni(NO3)2·6H2O to the above citric acid aqueous solution and stir at 80 °C for 1 h. Add 3 g of MgO and 11 g of commercially available MCM-41 molecular sieve to the above solution and stir at 80 °C for 8 h to form a gel. Then dry the gel at 100 °C and calcine it at 650 °C for 6 h at a calcination rate of 5 °C / min. Obtain the catalyst semi-finished solid.

[0113] 129g of ethanol, 29.4g of AEO-8, and 5.8g of Span40 were mixed. 12.9g of Ce(NO3)3·6H2O was dissolved in the mixed solution. 80g of the catalyst semi-finished product was then impregnated with the Ce(NO3)3·6H2O solution for 8 hours. After impregnation, the product was directly dried in an oven at 100℃, and then calcined in a muffle furnace. The muffle furnace heating method was as follows: 50℃-120℃ at a heating rate of 5℃ / min, 120℃-220℃ at a heating rate of 0.5℃ / min, and 220-450℃ at a heating rate of 5℃ / min. The product was then calcined at 450℃ for 4 hours to obtain catalyst CAT-3.

[0114] The composition of the catalyst is shown in Table 1.

[0115] The above catalyst was subjected to X-ray diffraction (XRD) testing, and the XRD pattern is shown below. Figure 1 As shown, the catalyst exhibits diffraction peaks at 2θ of 28.0°, 31.3°, and 32.7°, proving that the catalyst contains perovskite LaNiO3 and perovskite-like La2NiO4 structures, as well as CeO2.

[0116] The above catalyst was subjected to H2-TPR testing, and the results are as follows: Figure 3 As shown, the catalyst exhibits two reduction peaks at 366℃ and 386℃.

[0117] Example 4

[0118] Dissolve 68.8 g of citric acid in 258 mL of water and stir at 80 °C for 30 min until the citric acid is completely dissolved. Add 155 g of La(NO3)3·6H2O and 104 g of Ni(NO3)2·6H2O to the above citric acid aqueous solution and stir at 80 °C for 1 h. Add 2 g of MgO and 10 g of commercially available MCM-41 molecular sieve to the above solution and stir at 80 °C for 8 h to form a gel. Then dry the gel at 110 °C and calcine it at 650 °C for 6 h at a calcination rate of 5 °C / min. Obtain the catalyst semi-finished solid.

[0119] 260g of ethanol, 65g of PEG400, and 6.5g of Span80 were mixed. 50.5g of Ce(NO3)3·6H2O was dissolved in the mixed solution. Then, 80g of the catalyst semi-finished solid was impregnated with the Ce(NO3)3·6H2O solution for 8 hours. After impregnation, it was directly placed in an oven at 100℃ for drying, and then placed in a muffle furnace for calcination. The muffle furnace heating method was as follows: 50℃-120℃ at a heating rate of 5℃ / min, 120℃-220℃ at a heating rate of 0.5℃ / min, and 220-450℃ at a heating rate of 5℃ / min. Finally, it was calcined at 450℃ for 4 hours to obtain catalyst CAT-4.

[0120] The composition of the catalyst is shown in Table 1.

[0121] The above catalyst was subjected to X-ray diffraction (XRD) testing, and the XRD pattern is shown below. Figure 1 As shown, the catalyst exhibits diffraction peaks at 2θ of 28.0°, 31.2°, and 32.7°, proving that the catalyst contains perovskite LaNiO3 and perovskite-like La2NiO4 structures, as well as CeO2.

[0122] The above catalyst was subjected to H2-TPR testing, and the results are as follows: Figure 3 As shown, the catalyst exhibits a reduction peak at 390°C.

[0123] Example 5

[0124] 70.3 g of citric acid was dissolved in 264 mL of water and stirred at 80 °C for 30 min to ensure complete dissolution. 158.5 g of La(NO3)3·6H2O and 106.5 g of Ni(NO3)2·6H2O were added to the citric acid solution, and the mixture was stirred at 80 °C for 1 h. Then, 10 g of commercially available MCM-41 molecular sieve was added to the solution, and the mixture was stirred at 80 °C for 8 h to form a gel. The gel was then dried at 110 °C and calcined at 650 °C for 6 h at a heating rate of 5 °C / min. A semi-finished catalyst solid was obtained.

[0125] 40g of ethanol, 4g of PEG400, and 0.4g of Span80 were mixed. 8.4g of Ce(NO3)3·6H2O was dissolved in the mixed solution. Then, 80g of the catalyst semi-finished solid was impregnated with the Ce(NO3)3·6H2O solution for 8 hours. After impregnation, it was directly placed in an oven at 100℃ for drying, and then placed in a muffle furnace for calcination. The muffle furnace heating method was as follows: 50℃-120℃ at a heating rate of 5℃ / min, 120℃-220℃ at a heating rate of 0.5℃ / min, and 220-450℃ at a heating rate of 5℃ / min. Finally, it was calcined at 450℃ for 4 hours to obtain catalyst CAT-5.

[0126] The composition of the catalyst is shown in Table 1.

[0127] The above catalyst was subjected to X-ray diffraction (XRD) testing, and the XRD pattern was compared with... Figure 1 Similar to Example 1. H2-TPR testing of the above catalyst showed that it exhibited a reduction peak at 355°C and another at 386°C.

[0128] Example 6

[0129] 76.5 g of citric acid was dissolved in 286.6 mL of water and stirred at 80 °C for 30 min to ensure complete dissolution. 172.3 g of La(NO3)3·6H2O and 115.8 g of Ni(NO3)2·6H2O were added to the citric acid solution, and the mixture was stirred at 80 °C for 1 h. 2 g of commercially available MgO was then added to the solution, and the mixture was stirred at 80 °C for 8 h to form a gel. The gel was then dried at 110 °C and calcined at 650 °C for 6 h at a heating rate of 5 °C / min. A semi-finished catalyst solid was obtained.

[0130] 40g of ethanol, 4g of PEG400, and 0.4g of Span80 were mixed. 8.4g of Ce(NO3)3·6H2O was dissolved in the mixed solution. Then, 80g of the catalyst semi-finished solid was impregnated with the Ce(NO3)3·6H2O solution for 8 hours. After impregnation, it was directly placed in an oven at 100℃ for drying, and then placed in a muffle furnace for calcination. The muffle furnace heating method was as follows: 50℃-120℃ at a heating rate of 5℃ / min, 120℃-220℃ at a heating rate of 0.5℃ / min, and 220-450℃ at a heating rate of 5℃ / min. Finally, it was calcined at 450℃ for 4 hours to obtain catalyst CAT-6.

[0131] The composition of the catalyst is shown in Table 1.

[0132] The above catalyst was subjected to X-ray diffraction (XRD) testing, and the XRD pattern was compared with... Figure 1 Similar to Example 1. The above catalyst was subjected to H2-TPR testing, as shown... Figure 3 As shown, the catalyst exhibits two reduction peaks at 352 °C and 382 °C.

[0133] Example 7

[0134] 78.1 g of citric acid was dissolved in 293 mL of water and stirred at 80 °C for 30 min until completely dissolved. 176 g of La(NO3)3·6H2O and 118.3 g of Ni(NO3)2·6H2O were added to the citric acid solution, and the mixture was stirred at 80 °C for 9 h to form a gel. The gel was then dried at 110 °C and calcined at 650 °C for 6 h at a heating rate of 5 °C / min. A semi-finished catalyst solid was obtained.

[0135] 40g of ethanol, 4g of PEG400, and 0.4g of Span80 were mixed. 8.4g of Ce(NO3)3·6H2O was dissolved in the mixed solution. Then, 80g of the catalyst semi-finished solid was impregnated with the Ce(NO3)3·6H2O solution for 8 hours. After impregnation, it was directly placed in an oven at 100℃ for drying, and then placed in a muffle furnace for calcination. The muffle furnace heating method was as follows: 50℃-120℃ at a heating rate of 5℃ / min, 120℃-220℃ at a heating rate of 0.5℃ / min, and 220-450℃ at a heating rate of 5℃ / min. Finally, it was calcined at 450℃ for 4 hours to obtain catalyst CAT-7.

[0136] The composition of the catalyst is shown in Table 1.

[0137] The above catalyst was subjected to X-ray diffraction (XRD) testing, and the XRD pattern was compared with... Figure 1 Similar to Example 1. H2-TPR testing of the above catalyst showed two reduction peaks at 356°C and 392°C.

[0138] Example 8

[0139] Dissolve 68.8 g of citric acid in 258 mL of water and stir at 80 °C for 30 min until the citric acid is completely dissolved. Add 155 g of La(NO3)3·6H2O and 104 g of Ni(NO3)2·6H2O to the above citric acid aqueous solution and stir at 80 °C for 1 h. Add 2 g of MgO and 10 g of commercially available MCM-41 molecular sieve to the above solution and stir at 80 °C for 8 h to form a gel. Then dry the gel at 110 °C and calcine it at 650 °C for 6 h at a calcination rate of 5 °C / min. Obtain the catalyst semi-finished solid.

[0140] 40g of ethanol, 4g of PEG400, and 0.4g of Span80 were mixed. 8.4g of Ce(NO3)3·6H2O was dissolved in the mixed solution. Then, 80g of the catalyst semi-finished solid was impregnated with the Ce(NO3)3·6H2O solution for 8 hours. After impregnation, it was directly placed in an oven at 100℃ for drying, and then placed in a muffle furnace for calcination. The muffle furnace temperature was raised between 50℃ and 450℃ at a rate of 5℃ / min. The catalyst CAT-8 was obtained by calcination at 450℃ for 4 hours.

[0141] The composition of the catalyst is shown in Table 1.

[0142] The catalyst was subjected to X-ray diffraction (XRD) tests. The XRD pattern showed that the catalyst had diffraction peaks at 2θ of 28.1°, 31.3° and 32.8°, which proved that the catalyst formed a perovskite LaNiO3 structure and a perovskite-like La2NiO4 structure, and that CeO2 was present.

[0143] The catalyst was subjected to H2-TPR testing, which showed that the catalyst had a reduction peak at 390℃.

[0144] Comparative Example 1

[0145] 68.8 g of citric acid was dissolved in 258 mL of water and stirred at 80 °C for 30 min until completely dissolved. 155 g of La(NO3)3·6H2O and 104 g of Ni(NO3)2·6H2O were added to the citric acid solution, and the mixture was stirred at 80 °C for 1 h. Then, 2 g of MgO and 10 g of commercially available MCM-41 molecular sieve were added to the solution, and the mixture was stirred at 80 °C for 8 h to form a gel. The gel was then dried at 110 °C and calcined at 650 °C for 6 h at a calcination rate of 5 °C / min. Catalyst DCAT-1 was obtained.

[0146] The composition of the catalyst is shown in Table 2. H2-TPR testing of the catalyst revealed a reduction peak at 432℃ and another at 571℃.

[0147] Comparative Example 2

[0148] 77.6 g of Ni(NO3)2·6H2O was dissolved in 192 g of water and impregnated with 80 g of commercially available SiO2 support for 8 h. Then, it was dried at 110 °C and calcined at 650 °C for 6 h at a calcination rate of 5 °C / min. The resulting catalyst semi-finished solid was obtained.

[0149] 40g of ethanol, 4g of PEG400, and 0.4g of Span80 were mixed. 8.4g of Ce(NO3)3·6H2O was dissolved in the mixed solution. Then, 80g of the catalyst semi-finished solid was impregnated with the Ce(NO3)3·6H2O solution for 8 hours. After impregnation, it was directly placed in an oven at 100℃ for drying, and then placed in a muffle furnace for calcination. The muffle furnace heating method was as follows: 50℃-120℃ at a heating rate of 5℃ / min, 120℃-220℃ at a heating rate of 0.5℃ / min, and 220-450℃ at a heating rate of 5℃ / min. Finally, it was calcined at 450℃ for 4 hours to obtain catalyst DCAT-2.

[0150] H2-TPR testing of the above catalyst revealed a reduction peak at 421 °C. The composition of the catalyst is shown in Table 2.

[0151] Comparative Example 3

[0152] 77.6 g of Ni(NO3)2·6H2O was dissolved in 192 g of water and impregnated with 80 g of commercially available Al2O3 support for 8 h. Then, it was dried at 110 °C and calcined at 650 °C for 6 h at a calcination rate of 5 °C / min. The resulting catalyst semi-finished solid was obtained.

[0153] 40g of ethanol, 4g of PEG400, and 0.4g of Span80 were mixed. 8.4g of Ce(NO3)3·6H2O was dissolved in the mixed solution. Then, 80g of the catalyst semi-finished product solid was impregnated with the Ce(NO3)3·6H2O solution for 8 hours. After impregnation, it was directly placed in an oven at 100℃ for drying, and then placed in a muffle furnace for calcination. The muffle furnace heating method was as follows: 50℃-120℃ with a heating rate of 5℃ / min, 120℃-220℃ with a heating rate of 0.5℃ / min, and 220-450℃ with a heating rate of 5℃ / min. Finally, it was calcined at 450℃ for 4 hours to obtain catalyst DCAT-3.

[0154] H2-TPR testing of the above catalyst revealed a reduction peak at 431 °C. The composition of the catalyst is shown in Table 2.

[0155] Comparative Example 4

[0156] Dissolve 68.8 g of citric acid in 258 mL of water and stir at 80 °C for 30 min until the citric acid is completely dissolved. Add 155 g of La(NO3)3·6H2O and 104 g of Co(NO3)2·6H2O to the above citric acid aqueous solution and stir at 80 °C for 1 h. Add 2 g of MgO and 10 g of commercially available MCM-41 molecular sieve to the above solution and stir at 80 °C for 8 h to form a gel. Then dry the gel at 110 °C and calcine it at 650 °C for 6 h at a calcination rate of 5 °C / min. Obtain the catalyst semi-finished solid.

[0157] 40g of ethanol, 4g of PEG400, and 0.4g of Span80 were mixed. 8.4g of Ce(NO3)3·6H2O was dissolved in the mixed solution. Then, 80g of the catalyst semi-finished solid was impregnated with the Ce(NO3)3·6H2O solution for 8 hours. After impregnation, it was directly placed in an oven at 100℃ for drying, and then placed in a muffle furnace for calcination. The muffle furnace heating method was as follows: 50℃-120℃ at a heating rate of 5℃ / min, 120℃-220℃ at a heating rate of 0.5℃ / min, and 220-450℃ at a heating rate of 5℃ / min. Finally, it was calcined at 450℃ for 4 hours to obtain catalyst DCAT-4.

[0158] H2-TPR testing of the above catalyst revealed a reduction peak in the temperature range of 410-430℃. The composition of the catalyst is shown in Table 2.

[0159] Comparative Example 5

[0160] 77.6 g of Ni(NO3)2·6H2O was dissolved in 192 g of water and impregnated with 80 g of commercially available MCM-41 support for 8 h. Then, it was dried at 110 °C and calcined at 650 °C for 6 h at a calcination rate of 5 °C / min. The resulting catalyst semi-finished solid was obtained.

[0161] 40g of ethanol, 4g of PEG400, and 0.4g of Span80 were mixed. 8.4g of Ce(NO3)3·6H2O was dissolved in the mixed solution. Then, 80g of the catalyst semi-finished solid was impregnated with the Ce(NO3)3·6H2O solution for 8 hours. After impregnation, it was directly placed in an oven at 100℃ for drying, and then placed in a muffle furnace for calcination. The muffle furnace heating method was as follows: 50℃-120℃ at a heating rate of 5℃ / min, 120℃-220℃ at a heating rate of 0.5℃ / min, and 220-450℃ at a heating rate of 5℃ / min. Finally, it was calcined at 450℃ for 4 hours to obtain catalyst DCAT-5.

[0162] H2-TPR testing of the above catalyst revealed a reduction peak at 425℃. The composition of the catalyst is shown in Table 2.

[0163] Comparative Example 6

[0164] 78.1 g of citric acid was dissolved in 293 mL of water and stirred at 80 °C for 30 min until completely dissolved. 176 g of La(NO3)3·6H2O and 118.3 g of Ni(NO3)2·6H2O were added to the citric acid solution, and the mixture was stirred at 80 °C for 9 h to form a gel. The gel was then dried at 110 °C and calcined at 650 °C for 6 h at a calcination rate of 5 °C / min. Catalyst DCAT-6 was obtained.

[0165] The composition of the catalyst is shown in Table 2.

[0166] The above catalyst was subjected to X-ray diffraction (XRD) testing, such as... Figure 1 As shown, the catalyst's main phase is the perovskite LaNiO3 phase.

[0167] The catalyst was subjected to H2-TPR testing, which showed that the catalyst had three reduction peaks in the range of 400-650℃.

[0168] Comparative Example 7

[0169] 77.6 g of Ni(NO3)2·6H2O was dissolved in 192 g of water and impregnated with 80 g of commercially available CeO2 support for 8 h. Then, it was dried at 110 °C and calcined at 650 °C for 6 h at a calcination rate of 5 °C / min. The catalyst DCAT-7 was obtained.

[0170] The composition of the catalyst is shown in Table 2.

[0171] The above catalyst was subjected to X-ray diffraction (XRD) testing, such as... Figure 1As shown, the catalyst's main phase is CeO2.

[0172] The catalyst was subjected to H2-TPR testing, which showed that the catalyst had two reduction peaks in the range of 410-480℃.

[0173] Comparative Example 8

[0174] Dissolve 68.8 g of citric acid in 258 mL of water and stir at 80 °C for 30 min until the citric acid is completely dissolved. Add 155 g of La(NO3)3·6H2O and 104 g of Ni(NO3)2·6H2O to the above citric acid aqueous solution and stir at 80 °C for 1 h. Add 2 g of MgO and 10 g of commercially available MCM-41 molecular sieve to the above solution and stir at 80 °C for 8 h to form a gel. Then dry the gel at 110 °C and calcine it at 650 °C for 6 h at a calcination rate of 5 °C / min. Obtain the catalyst semi-finished solid.

[0175] Take 40g of water and dissolve 8.4g of Ce(NO3)3·6H2O in the above mixed solution. Then, impregnate 80g of catalyst semi-finished solid with the solution containing Ce(NO3)3·6H2O for 8h. After impregnation, dry it directly in an oven at 100℃. Then, calcine it in a muffle furnace. The heating method of the muffle furnace is as follows: 50℃-120℃, heating rate of 5℃ / min; 120℃-220℃, heating rate of 0.5℃ / min; 220-450℃, heating rate of 5℃ / min. Then, calcine at 450℃ for 4h to obtain catalyst DCAT-8.

[0176] The composition of the catalyst is shown in Table 2.

[0177] X-ray diffraction (XRD) tests were performed on the above catalyst, and no characteristic peaks of La2NiO4 were found.

[0178] The above catalyst was subjected to H2-TPR testing, such as... Figure 4 As shown, a large number of high-temperature reduced nickel species exist above 400℃.

[0179] Table 1

[0180]

[0181]

[0182] Note: In the table above, the CeO2 content is based on the total amount of catalyst, while the content of auxiliary elements and molecular sieves is based on the mass of the semi-finished catalyst.

[0183] Table 2

[0184]

[0185] Note: In the table above, the CeO2 content is based on the total amount of catalyst, while the content of auxiliary elements and molecular sieves is based on the mass of the semi-finished catalyst.

[0186] Test case

[0187] The catalysts used in the above examples and comparative examples were evaluated for methane-carbon dioxide reforming reactions.

[0188] The catalyst was first reduced at 450℃ and a hydrogen pressure of 0.3 MPa for 4 hours, followed by a methane-carbon dioxide reforming reaction. The reaction conditions included: a methane to carbon dioxide molar ratio of 1:1.2, a reaction temperature of 800℃, a pressure of 0.3 MPa, and a total space velocity of 20,000 h⁻¹ for the feed gas. -1 After 96 hours of reaction, the product was collected, and its composition was analyzed by gas chromatography. The CO2 conversion rate and CH4 conversion rate were calculated, and the amount of carbon deposited on the catalyst was tested by thermogravimetric analysis in air. The results are shown in Table 3.

[0189]

[0190]

[0191] The catalysts of Examples 1, 6, and Comparative Example 1 were evaluated for stability under the same conditions described above. The changes in CO2 conversion rate after 500 h of continuous reaction are shown in the figure below. Figure 5 As shown.

[0192] Table 3

[0193]

[0194]

[0195] As can be seen from the results in Table 3, the catalyst prepared using the embodiments provided by this invention exhibits high CO2 and CH4 conversion rates after 96 hours of reaction, and low carbon deposition. The thermogravimetric analysis (TGA) diagrams of the catalysts in Examples 1, 6, and Comparative Example 6 after 100 hours of reaction under an oxygen atmosphere are shown below. Figure 6 As shown, the catalyst provided by this invention has strong resistance to carbon deposition and good stability.

[0196] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of 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 catalyst, characterized in that, The catalyst comprises an active matrix and CeO2, wherein the active matrix comprises a La-Ni-based oxide with a perovskite structure; X-ray diffraction analysis showed that the catalyst exhibited good performance at 2... Diffraction peaks are observed at 32.7±0.3°, 31.3±0.3°, and 28.0±0.3°. The active matrix also includes auxiliary elements, which are selected from at least one alkaline earth metal; The catalyst also includes a molecular sieve, which is an all-silica mesoporous molecular sieve. H2-TPR analysis revealed that the catalyst exhibited at least two reduction peaks at 350-390℃. Based on the total amount of the catalyst, the CeO2 content is 1-6 wt%.

2. The catalyst according to claim 1, wherein, After the catalyst was reduced at 450°C for 2 hours in a hydrogen atmosphere, the average particle size of Ni particles, as measured by X-ray diffraction, was 13-22 nm.

3. The catalyst according to claim 2, wherein, After the catalyst was reduced at 450°C for 2 hours in a hydrogen atmosphere, the average particle size of Ni particles, as measured by X-ray diffraction, was 15-18 nm.

4. The catalyst according to claim 1, wherein, Based on the total amount of the catalyst, the CeO2 content is 2-4 wt%.

5. The catalyst according to claim 1, wherein, XPS characterization showed that the molar ratio of Ni to Ce in the catalyst was (1-20):

1.

6. The catalyst according to claim 5, wherein, XPS characterization revealed that the molar ratio of Ni to Ce in the catalyst was (2-15):

1.

7. The catalyst according to claim 1, wherein, The Ni element in the La-Ni-based oxide with a perovskite structure includes both divalent and trivalent nickel.

8. The catalyst according to claim 1, wherein, XPS characterization showed that the molar ratio of Ni to La in the catalyst was (1.5-2.5):

1.

9. The catalyst according to claim 8, wherein, XPS characterization showed that the molar ratio of Ni to La in the catalyst was (1.8-2.2):

1.

10. The catalyst according to claim 1, wherein, The auxiliary element is selected from at least one of Mg, Ca and Sr.

11. The catalyst according to claim 10, wherein, The auxiliary element is Mg.

12. The catalyst according to any one of claims 1-11, wherein, Based on the total mass of the active matrix, the content of the auxiliary element, calculated as oxide, is 1-5 wt%.

13. The catalyst according to claim 12, wherein, Based on the total mass of the active matrix, the content of the auxiliary element, calculated as oxide, is 1.5-3 wt%.

14. The catalyst according to claim 13, wherein, Based on the total mass of the active matrix, the content of the molecular sieve, calculated as silica, is 5-15 wt%.

15. The catalyst according to claim 14, wherein, Based on the total mass of the active matrix, the content of the molecular sieve, calculated as silica, is 9-11 wt%.

16. The catalyst according to claim 15, wherein, The molecular sieve is at least one of MCM-41, SBA-15, MCM-48 and SBA-16 molecular sieves.

17. The catalyst according to claim 16, wherein, The molecular sieve is an MCM-41 type molecular sieve.

18. A method for preparing the catalyst according to any one of claims 1-17, characterized in that, Includes the following steps: (1) In the presence of a complexing agent, a La source, a Ni source, and a solvent are mixed to obtain a mixture; The mixture also includes a precursor of an auxiliary element, wherein the auxiliary element is at least one of alkaline earth metals; In step (1), the mixture also includes a molecular sieve, which is an all-silica mesoporous molecular sieve; (2) The mixture is reacted to form a gel, and then subjected to a first calcination to obtain a semi-finished catalyst; (3) In the presence of a surfactant, a solution of a Ce-containing soluble compound is contacted with the semi-finished catalyst, and then a second calcination is performed; The surfactants include polyoxyethylene nonionic surfactants and polyol nonionic surfactants; The amount of the solution containing the Ce-soluble compound used is such that the CeO2 content in the prepared catalyst is 1-6 wt%.

19. The preparation method according to claim 18, wherein, In step (1), the molar ratio of the Ni source to the La source is (0.5-2):1, calculated by metal elements.

20. The preparation method according to claim 19, wherein, In step (1), the molar ratio of the Ni source to the La source is (0.5-1.5):1, calculated by metal elements.

21. The preparation method according to claim 18, wherein, The total molar amount of the La source and Ni source, calculated as metal elements, is in a molar ratio of 0.5-3:1 to the complexing agent.

22. The preparation method according to claim 18, wherein, The auxiliary element is selected from at least one of Mg, Ca and Sr.

23. The preparation method according to claim 22, wherein, The auxiliary element is Mg.

24. The preparation method according to claim 18, wherein, The amount of the auxiliary element precursor used is such that the content of the auxiliary element, calculated as oxide, in the obtained semi-finished catalyst is 1-5 wt%.

25. The preparation method according to claim 24, wherein, The amount of the auxiliary element precursor used is such that the content of the auxiliary element, calculated as oxide, in the obtained semi-finished catalyst is 1.5-3 wt%.

26. The preparation method according to claim 18, wherein, In step (2), the reaction conditions include: a temperature of 50-100℃ and a time of 1-12h.

27. The preparation method according to claim 26, wherein, In step (2), the reaction conditions include a temperature of 60-90℃ and a time of 6-8h.

28. The preparation method according to claim 18, wherein, The conditions for the first roasting include: a temperature of 300-1200℃ and a time of 2-20h.

29. The preparation method according to claim 18, wherein, The polyoxyethylene nonionic surfactant is selected from polyethylene glycol and / or fatty alcohol polyoxyethylene ether.

30. The preparation method according to claim 29, wherein, The polyoxyethylene nonionic surfactant is at least one of PEG200, PEG400, PEG600, AEO-7, AEO-8 and AEO-9.

31. The preparation method according to claim 18, wherein, The polyol nonionic surfactant is a dehydrated sorbitan fatty acid ester.

32. The preparation method according to claim 31, wherein, The polyol nonionic surfactant is at least one of sorbitan monopalmitate, sorbitan monooleate, and sorbitan monostearate.

33. The preparation method according to claim 18, wherein, The mass ratio of the polyoxyethylene nonionic surfactant to the polyol nonionic surfactant is 1:(0.1-1).

34. The preparation method according to claim 33, wherein, The mass ratio of the polyoxyethylene nonionic surfactant to the polyol nonionic surfactant is 1:(0.1-0.5).

35. The preparation method according to claim 18, wherein, The mass ratio of the soluble compound of Ce, calculated as CeO2, to the mass of the surfactant is 1:(1-10).

36. The preparation method according to claim 35, wherein, The mass ratio of the soluble Ce compound, calculated as CeO2, to the mass of the surfactant is 1:(1-8).

37. The preparation method according to claim 18, wherein, The amount of the solution containing the Ce-soluble compound used is such that the CeO2 content in the prepared catalyst is 2-4 wt%.

38. The preparation method according to claim 18, wherein, The conditions for the second calcination include: a calcination temperature of 400-600℃ and a constant temperature time of 2-6 hours.

39. The preparation method according to claim 38, wherein, The second calcination method includes: first heating to 100-150℃ at a heating rate of 3-6℃ / min, then heating to 200-250℃ at a heating rate of 0.2-0.6℃ / min, and then heating to the calcination temperature at a heating rate of 3-6℃ / min for constant temperature.

40. The preparation method according to claim 18, wherein, The amount of molecular sieve used is such that the content of the molecular sieve, calculated as silica, in the obtained semi-finished catalyst is 5-15 wt%.

41. The preparation method according to claim 40, wherein, The amount of molecular sieve used is such that the content of the molecular sieve, calculated as silica, in the obtained semi-finished catalyst is 9-11 wt%.

42. The preparation method according to claim 18, wherein, The molecular sieve is selected from at least one of the molecular sieves MCM-41, SBA-15, MCM-48, and SBA-16.

43. The preparation method according to claim 42, wherein, The molecular sieve is MCM-41.

44. The preparation method according to any one of claims 18-43, wherein, The molecular sieve has an average pore size of 1-15 nm.

45. The use of the catalyst according to any one of claims 1-17 or the catalyst prepared by the preparation method according to any one of claims 18-44 in the methane-carbon dioxide reforming reaction.

46. ​​A method for methane-carbon dioxide reforming reaction, characterized in that, include: Under reforming reaction conditions, methane and carbon dioxide are contacted with a catalyst, wherein the catalyst is the catalyst according to any one of claims 1-17 or the catalyst prepared by the preparation method according to any one of claims 18-44.

47. The method according to claim 46, wherein, The reforming reaction conditions include: a molar ratio of methane to carbon dioxide of 1:1-2; a reaction temperature of 700-950℃; a pressure of 0.1-1 MPa; and a total space velocity of 10000-30000 h⁻¹ for the feed gas. -1 .

48. The method according to claim 47, wherein, The reforming reaction conditions include: a molar ratio of methane to carbon dioxide of 1:1.2-1.5; a reaction temperature of 750-850℃; a pressure of 0.1-0.5 MPa; and a total space velocity of 15000-25000 h⁻¹ for the feed gas. -1 .

49. The method according to claim 48, wherein, The reforming reaction conditions include: a reaction temperature of 780-800℃; a pressure of 0.2-0.4 MPa; and a total space velocity of 18000-22000 h⁻¹ for the feed gas. -1 .

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