Catalyst and preparation method therefor and use thereof, and method for reforming reaction of methane and carbon dioxide

Abstract

A catalyst and a preparation method therefor and a use thereof, and a method for reforming reaction of methane and carbon dioxide. The catalyst comprises an active matrix and CeO22, wherein the active matrix comprises La-Ni-based oxide having a perovskite structure; upon X-ray diffraction measurement, the catalyst has diffraction peaks at 2θ of 32.7±0.3°, 31.3±0.3°, and 28.0±0.3°; and upon H2-TPR measurement, the catalyst has at least one reduction peak at 400°C or below, and based on the total amount of the catalyst, the content of CeO2 is 1-20 wt%. The catalyst has relatively high activity and stability, can effectively enhance the adsorption of Co2 and reduce the adsorption and cracking of CH4 in the reaction process, and has good carbon deposition resistance.

Description

Catalyst, preparation method and application thereof, and method for methane carbon dioxide reforming reaction

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202310636802.0 filed on May 31, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of catalysts, and in particular to a catalyst, a preparation method and application thereof, and a method for methane carbon dioxide reforming reaction. Background Art

[0004] Both methane and carbon dioxide are greenhouse gases. Methane-CO2 reforming to produce synthesis gas (syngas) is an effective way to utilize CO2 on a large scale. It also utilizes relatively inexpensive natural gas to generate synthesis gas (CO + H2), which can be further converted into other high-value-added downstream hydrocarbon products. However, a major challenge with this reaction process is that the catalysts used in methane-CO2 reforming to produce synthesis gas are primarily nickel-based, which is prone to carbon deposition. If this carbon deposition problem cannot be effectively addressed, it will severely limit the stability of the catalyst and its industrialization.

[0005] Perovskites have become a focus of attention in many fields due to their excellent electrical conductivity, magnetism, thermoelectricity, piezoelectricity and other properties, low preparation cost, and thermodynamic and mechanical stability at high temperatures. Perovskite composite oxide materials are excellent oxygen ion and electron conductors under high temperature conditions, can also release oxygen under inert conditions, and can replenish oxygen through the redox (oxidation-reduction) process. Therefore, using perovskite oxides as catalysts for the methane-carbon dioxide reforming reaction can effectively eliminate carbon deposits on the catalyst surface, which is beneficial to improving the catalyst's resistance to carbon deposition. However, the catalyst's activity and resistance to carbon deposition are still not very ideal.

[0006] CN113600200A discloses a method for preparing a Ni-based alkaline earth metal modified catalyst for methane dry gas reforming with carbon deposition resistance, wherein an alkaline earth metal-doped LaAl perovskite carrier is first prepared, and then Ni is loaded on the carrier by an impregnation method. However, the stability of the catalyst is still unsatisfactory. CN114588912A discloses a method for preparing a perovskite catalyst suitable for methane dry reforming, wherein LaAl is doped with alkali metal K ions at the A position of LaNiO3 perovskite to form a LaAl perovskite catalyst. x K 1-xNiO3 is then added to a stable, high-oxygen-capacity CeO2 solid powder. CN114471581A discloses a carbon-deposition-resistant methane-CO2 reforming catalyst, which loads Ce on the surface of a perovskite oxide to obtain a Ce-loaded ABO3 perovskite oxide catalyst. All of these solutions utilize CeO2's oxygen storage properties to quickly eliminate carbon deposits on the catalyst surface during the methane-CO2 reforming reaction. However, the high CeO2 loading is not conducive to improving catalyst activity.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to overcome the problems of insufficient activity, poor stability and poor carbon deposition resistance of methane-carbon dioxide reforming catalysts in the prior art, and to provide a catalyst, a preparation method and application thereof, and a method for methane-carbon dioxide reforming reaction. The catalyst has good carbon deposition resistance, high activity and stability.

[0009] To achieve the above-mentioned object, the present invention provides a catalyst in a first aspect, comprising an active matrix and CeO2, wherein the active matrix comprises a La-Ni-based oxide having a perovskite structure; the catalyst has diffraction peaks at 2θ of 32.7±0.3°, 31.3±0.3°, and 28.0±0.3° as measured by X-ray diffraction;

[0010] The catalyst showed at least one reduction peak below 400 °C as measured by H2-TPR;

[0011] Based on the total amount of the catalyst, the content of CeO2 is 1-20wt%.

[0012] Preferably, based on the total amount of the catalyst, the content of CeO2 is 1-6 wt%, preferably 2-4 wt%.

[0013] A second aspect of the present invention provides a method for preparing a catalyst, comprising the following steps:

[0014] (1) mixing a La source and a Ni source in the presence of a complexing agent to obtain a mixture;

[0015] (2) reacting the mixture to form a gel, and then performing a first calcination to obtain a semi-finished catalyst;

[0016] (3) contacting a solution of a soluble compound containing Ce with the semi-finished catalyst in the presence of a surfactant, and then performing a second calcination;

[0017] Wherein, the surfactant includes polyoxyethylene nonionic surfactant and polyol nonionic surfactant.

[0018] The third aspect of the present invention provides use of the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect in a methane-carbon dioxide reforming reaction.

[0019] A fourth aspect of the present invention provides a method for methane carbon dioxide reforming reaction, comprising: under reforming reaction conditions, contacting methane and carbon dioxide with a catalyst, wherein the catalyst is the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect.

[0020] The catalyst provided by the present invention has high activity and stability, can effectively enhance the adsorption of CO2, reduce the adsorption and cracking of CH4 during the reaction process, and has good anti-carbon deposition performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is an XRD spectrum of the catalysts prepared in Examples 1, 2, 3, 4 of the present invention and Comparative Examples 6 and 7;

[0022] FIG2 is a crystal phase analysis spectrum of the catalyst samples prepared in Example 1 and Comparative Example 2 of the present invention;

[0023] FIG3 is an H2-TPR curve of the catalysts prepared in Examples 1, 2, 3, 4, 6 and Comparative Example 6 of the present invention;

[0024] FIG4 is an H2-TPR curve of the catalysts prepared in Example 1 of the present invention and Comparative Example 8;

[0025] FIG5 is a stability evaluation result of the catalysts prepared in Examples 1 and 6 of the present invention and Comparative Example 1;

[0026] FIG6 is a thermogravimetric diagram of the catalysts prepared in Example 1, Example 6 and Comparative Example 6 of the present invention after 100 hours of reaction. DETAILED DESCRIPTION

[0027] The endpoints of the ranges and any values ​​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 endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0028] A 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; the catalyst has diffraction peaks at 2θ of 32.7±0.3°, 31.3±0.3°, and 28.0±0.3° as measured by X-ray diffraction; and the catalyst has at least one reduction peak below 400°C as measured by H2-TPR;

[0029] Based on the total amount of the catalyst, the content of CeO2 is 1-20wt%.

[0030] In the present invention, the term "perovskite structure" has a broad definition, referring to a crystal structure identical to or similar to the perovskite CaTiO3. "La-Ni-based oxide having a perovskite structure" refers to a compound containing the elements Li, Ni, and O and having a crystal structure identical to or similar to the perovskite CaTiO3, and may include LaNiO3 and / or La2NiO4.

[0031] In the prior art, research on perovskite catalysts is generally limited to element doping or loading, and there is a lack of research on the special structure of perovskite composite oxide materials. The catalyst provided by the present invention has a special composite perovskite structure, and X-ray diffraction (XRD) shows that the catalyst has diffraction peaks at 32.7±0.3°, 31.3±0.3°, and 28.0±0.3°. According to the JCPDS standard card fitting analysis, the diffraction peak at 2θ of 32.7±0.3° belongs to the LaNiO3 species of the perovskite structure, the diffraction peak at 2θ of 31.3±0.3° belongs to the La2NiO4 species of the perovskite-like structure, and the diffraction peak at 2θ of 28.0±0.3° belongs to the CeO2 species.

[0032] In the present invention, X-ray diffraction (XRD) tests were performed on an X'Pert3 Powder diffractometer using a Cu Kα target line (incident wavelength ), the scanning range was 0-90°, and the scanning speed was 10° / min.

[0033] In the present invention, the phrase “the catalyst has at least one reduction peak below 400°C” means that the reduction temperature corresponding to the top of the reduction peak in the H2-TPR curve is below 400°C. Similarly, the following descriptions of the reduction temperature all refer to the temperature corresponding to the top of the reduction peak in the H2-TPR curve.

[0034] In the prior art, the reduction temperature of Ni-based catalysts is relatively high. The reduction temperatures of currently reported Ni-based perovskite composite oxides are generally above 400°C. In the present invention, the catalyst exhibits at least one reduction peak below 400°C as measured by H2-TPR. Preferably, the catalyst exhibits at least one reduction peak at 350-390°C as measured by H2-TPR. Further preferably, the catalyst exhibits at least two reduction peaks at 350-390°C. For example, one reduction peak may be present at 350-370°C and another at 380-390°C.

[0035] In the present invention, the test conditions of H2-TPR include:

[0036] The reduction behavior of the catalyst was tested 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 raised to 150°C at a rate of 10°C / min in an N2 atmosphere, maintained for 30 minutes, and then cooled to room temperature. The gas was switched to a 5 vol% H2-95 vol% N2 atmosphere and the temperature was raised to 900°C at a rate of 10°C / min to obtain an H2-TPR curve. The exhaust gas was detected using a TCD.

[0037] In the present invention, the catalyst has a lower reduction temperature, higher activity and stability. The reason for this may be that CeO2 is dispersed on the surface of the La-Ni-based oxide to form an interface effect. Under the synergistic effect of CeO2, the special spatial structural characteristics of the coexistence of the LaNiO3 structure with an infinite perovskite layer and the La2NiO4 structure with an interlaced rock salt layer and perovskite layer are more conducive to the reduction of Ni, greatly reducing the reduction temperature of the catalyst, and further helping to reduce the average particle size of the Ni particles after reduction. At the same time, the presence of this interface structure can significantly improve the electron transfer ability and oxygen vacancy transmission ability of the catalyst during the reaction process, improve the catalyst's ability to inhibit the carbon deposition process and its ability to convert the generated carbon deposition, thereby improving the activity and stability of the catalyst.

[0038] 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 may be a Ni species in a La2NiO4 structure, and the trivalent nickel may be a Ni species in a LaNiO3 structure.

[0039] In a further preferred embodiment, the area of ​​the characteristic peak of the catalyst at 2θ of 32.7±0.3° is measured by X-ray diffraction as S1, the peak area of ​​the diffraction peak at 2θ of 31.3±0.3° is S2, and the ratio S2 / S1 is (0.5-1.5):1, preferably (1.1-1.4):1. In the above preferred embodiment, the catalyst contains an appropriate ratio of LaNiO3 and La2NiO4 species, which is beneficial to further improve the activity and stability of the catalyst and improve its anti-carbon deposition performance.

[0040] In the present invention, the peak area of ​​the diffraction peak in the XRD spectrum is measured by the Gaussian fitting integration method.

[0041] In a further preferred embodiment, the molar ratio of Ni element to La element in the catalyst is (1.5-2.5) : 1 as characterized by XPS, for example, it can be 1.5: 1, 1.6: 1, 1.7: 1, 1.8: 1, 1.9: 1, 2: 1, 2.1: 1, 2.2: 1, 2.3: 1, 2.4: 1, 2.5: 1 and other typical but non-limiting molar ratios or ranges therebetween. Preferably, the molar ratio of Ni element to La element in the catalyst is (1.8-2.2) : 1 as characterized by XPS.

[0042] In the present invention, the element valence and surface element content were measured by XPS. XPS characterization was performed on an AXIS-ULTRAD LD-ray photoelectron spectrometer using a monochromatic Al-Kα target source and at a 1×10 -8 The samples were vacuumed under the conditions of 100 Pa. To deduct the charging effect, the C1s peak (binding energy of 284.6 eV) of contaminated carbon was used as the calibration standard.

[0043] According to some preferred embodiments of the present invention, after the catalyst is reduced at 450°C for 2 hours under a hydrogen atmosphere, the average particle size of Ni measured by XRD is 13-22 nm, for example, it can be 13 nm, 15 nm, 16 nm, 17 nm, 18 nm, 20 nm, 22 nm, etc., which are typical but non-limiting particle size values ​​or ranges between any two. Preferably, the average particle size of Ni is 15-18 nm. In the prior art, the average particle size of Ni after reduction of Ni-based perovskite catalysts is generally 30-45 nm. The catalyst provided by the present invention has a smaller grain size after reduction.

[0044] In the present invention, the method for measuring the average particle size of Ni particles specifically includes: measuring the average particle size of Ni at 2θ=44.5° by XRD characterization. 0 The crystal diffraction angle and half-peak width of the phase are measured, and then the grain size of the active center is measured using the Scherrer formula.

[0045] In the prior art, CeO2 is introduced into the catalyst mainly to utilize CeO2's oxygen storage performance, which is conducive to eliminating carbon deposits on the catalyst surface during the reaction. However, in order to achieve the above purpose, a higher CeO2 content is required, usually more than 10wt%. In the present invention, CeO2 is introduced to form an interfacial effect, and the content of CeO2 does not need to be too high. According to the present invention, based on the total amount of the catalyst, the content of the CeO2 is 1-20wt%, for example, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%. Preferably, based on the total amount of the catalyst, the content of the CeO2 is 1-6wt%, preferably 2-4wt%. Under the above preferred conditions, it is conducive to the formation of the largest interface between CeO2 and the perovskite matrix. If the CeO2 content is too low, the contact surface between CeO2 and the perovskite matrix will be smaller. If the CeO2 content is too high, the excess CeO2 will cover most of the perovskite matrix surface, resulting in reduced interface exposure and reduced activity.

[0046] The composition of the catalyst was analyzed by X-ray fluorescence spectrometry (XRF, EAGLE III, EDAX Inc.) by performing a full element scan on the catalyst to analyze the elemental composition and content of each element.

[0047] In a further preferred embodiment, XPS characterization shows that the molar ratio of Ni element to Ce element in the catalyst is (1-20):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 18:1, 20:1, etc., and preferably (2-15):1.

[0048] According to a preferred embodiment of the present invention, the active matrix further includes a promoter element, which is selected from at least one alkaline earth metal, preferably at least one selected from Mg, Ca, and Sr, and more preferably Mg. This preferred embodiment further improves the catalyst's carbon deposition resistance and stability.

[0049] According to the present invention, preferably, based on the total mass of the active matrix, the content of the auxiliary element calculated as oxide is 1-5wt%, for example, it can be 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 4wt%, 5wt%, etc., preferably 1.5-3wt%.

[0050] According to a preferred embodiment of the present invention, the active matrix further includes a molecular sieve. The molecular sieve's regular pore structure and well-developed surface organic groups (such as hydroxyl groups) within the pores interact with the perovskite, thereby further improving the catalyst's carbon deposition resistance and further limiting the average particle size of the Ni particles.

[0051] Preferably, based on the total mass of the active matrix, the content of the molecular sieve calculated as silicon dioxide is 5-15wt%, for example, it can be 5wt%, 8wt%, 9wt%, 9.5wt%, 10wt%, 10.5wt%, 11wt%, etc., preferably 9-11wt%.

[0052] In the present invention, the presence of the molecular sieve can be proved by crystal phase analysis, and its content is characterized by XRF method.

[0053] The crystal phase analysis of the samples was carried out on a Philips PW1710 X-ray diffractometer with a Cu target, a Kα radiation source, a tube voltage of 40 kV, a tube current of 30 mA, a scanning step of 0.02°, a scanning speed of 1.2° / min, and a scanning range of 2θ = 1-10°.

[0054] In a further preferred embodiment, the molecular sieve is an all-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, more preferably MCM-41 molecular sieve.

[0055] 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; and the catalyst has diffraction peaks at 2θ of 32.7±0.3°, 31.3±0.3°, and 28.0±0.3° as measured by X-ray diffraction;

[0056] The catalyst showed at least one reduction peak below 400 °C as measured by H2-TPR;

[0057] Based on the total amount of the catalyst, the content of CeO2 is 1-20wt%.

[0058] The selection range and content of the auxiliary element and molecular sieve are the same as those provided above and will not be repeated here.

[0059] A second aspect of the present invention provides a method for preparing a catalyst, comprising the following steps:

[0060] (1) mixing a La source, a Ni source, and a solvent in the presence of a complexing agent to obtain a mixture;

[0061] (2) reacting the mixture to form a gel, and then performing a first calcination to obtain a semi-finished catalyst;

[0062] (3) contacting a solution of a soluble compound containing Ce with the semi-finished catalyst in the presence of a surfactant, and then performing a second calcination;

[0063] Wherein, the surfactant includes polyoxyethylene nonionic surfactant and polyol nonionic surfactant.

[0064] According to some preferred embodiments of the present invention, in step (1), the molar ratio of the Ni source to the La source, calculated as metal elements, is (0.5-2):1, preferably (0.5-1.5):1, for example, it can be 0.5:1, 1:1, 1.5:1, etc.

[0065] Preferably, the molar ratio of the total molar amount of the La source and the Ni source calculated as metal elements to the complexing agent is 0.5-3:1, preferably 1-2:1.

[0066] In the present invention, the selection range for the specific types of the La source and Ni source is relatively wide, and soluble organic salts or inorganic salts of metals can be applied to the present invention, for example, at least one of metal nitrates, acetates and oxalates can be selected.

[0067] The La source and Ni source may further contain crystal water, which is well known to those skilled in the art.

[0068] In the present invention, the selection range of the complexing agent is relatively wide, and any complexing agent that can achieve complexation of La source and Ni source in the art can be used in the present invention. Preferably, the complexing agent is selected from citric acid and / or ethylenediaminetetraacetic acid.

[0069] According to some preferred embodiments of the present invention, the mixing method can be to first dissolve the complexing agent in a solvent and then mix it with the La source and the Ni source. The mixing in step (1) can be carried out under stirring conditions. The present invention does not particularly limit the specific conditions of the stirring, as long as the components can be fully mixed. Preferably, the mixing temperature is 50-100°C.

[0070] The present invention has a wide range of choices for the solvent in step (1), preferably, the solvent is water. The present invention also has no particular limitation on the amount of the solvent, as long as the components are fully dispersed and mixed.

[0071] According to a preferred embodiment of the present invention, in step (1), the mixture further includes an auxiliary element precursor, and the auxiliary element is at least one of alkaline earth metals, preferably at least one selected from Mg, Ca and Sr, and more preferably Mg.

[0072] Preferably, the amount of the auxiliary element precursor is such that the content of the auxiliary element in the semi-finished catalyst calculated as oxide is 1-5wt%, for example, it can be 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 4wt%, 5wt%, etc., preferably 1.5-3wt%.

[0073] According to some preferred embodiments of the present invention, the auxiliary element precursor may be an oxide of the auxiliary element or any substance that can form an oxide thereof by calcination, such as at least one of nitrate, acetate and oxalate containing the auxiliary element.

[0074] According to some preferred embodiments of the present invention, in step (1), the mixture further comprises a molecular sieve. The mixing method may be to first dissolve the complexing agent in a solvent and then mix it with the La source, the Ni source, the optional auxiliary element precursor, and the optional molecular sieve.

[0075] Preferably, the amount of the molecular sieve is such that the content of the molecular sieve in the semi-finished catalyst calculated as silicon dioxide is 5-15wt%, for example, 5wt%, 8wt%, 9wt%, 9.5wt%, 10wt%, 10.5wt%, 11wt%, etc., preferably 9-11wt%.

[0076] The selection range of the molecular sieve is the same as that described in the first aspect of the present invention, and will not be repeated here.

[0077] Preferably, the average pore size of the molecular sieve is 1-15 nm, preferably 5-10 nm. The molecular sieve with the preferred pore structure is advantageous in better controlling the crystal size of the catalyst and preventing aggregation.

[0078] According to some preferred embodiments of the present invention, in step (2), the reaction conditions include: temperature of 50-100° C., preferably 60-90° C., and time of 1-12 h, preferably 6-8 h.

[0079] Preferably, the first calcination is performed at a temperature of 300-1200°C, preferably 400-600°C, for 2-20 hours, preferably 4-8 hours. Drying may be performed 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°C.

[0080] In the present invention, under the synergistic effect of polyoxyethylene nonionic surfactants and polyol nonionic surfactants, it is beneficial to form an interface effect between CeO2 / La-Ni based oxides, thereby helping to lower the reduction temperature of the catalyst and improve the activity and stability of the catalyst.

[0081] 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 further preferably PEG400.

[0082] 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).

[0083] In a further preferred embodiment, the mass ratio of the polyoxyethylene nonionic surfactant to the polyol nonionic surfactant is 1:(0.1-1), for example, it can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1 or the like, or a range therebetween. Preferably, the mass ratio of the polyoxyethylene nonionic surfactant to the polyol nonionic surfactant is 1:(0.1-0.5), more preferably 1:(0.1-0.2). In the above preferred case, it is beneficial to achieve good dispersion of CeO2 on the catalyst surface and optimize the interfacial effect.

[0084] In the present invention, the purpose of the present invention can be achieved as long as the contact in step (3) is carried out in the presence of the surfactant. According to some preferred embodiments of the present invention, the mass ratio of the soluble Ce compound calculated as CeO2 to the surfactant is 1:(1-10), for example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc., preferably 1:(1-8). In the above preferred case, it is beneficial to further improve the activity and stability of the catalyst.

[0085] The present invention has no particular limitation on the method of introducing the surfactant. The surfactant can be prepared into a solution together with a soluble compound of Ce and then contacted with the semi-finished catalyst; or the surfactant can be introduced by contacting a solution containing a soluble compound of Ce with the semi-finished catalyst.

[0086] In the present invention, the selection range of the Ce-soluble compound is relatively wide, as long as it can provide the Ce element. Preferably, the Ce-soluble compound is selected from at least one of cerium nitrate, cerium acetate and cerium oxalate.

[0087] According to the present invention, the solvent in the solution of the soluble compound containing Ce can be selected from conventional organic solvents in the art, preferably at least one of alcohols, ketones or hydrocarbons, preferably at least one of methanol, ethanol, acetone and petroleum ether, more preferably ethanol and / or methanol.

[0088] The present invention has no particular limitation on the amount of the solvent, as long as it can dissolve the soluble Ce compound. Preferably, the mass ratio of the soluble Ce compound calculated as oxide to the solvent is 1:(1-50), preferably 1:(10-30).

[0089] According to the present invention, preferably, the amount of the solution containing a soluble compound of Ce is such that the content of CeO2 in the catalyst obtained is 1-20wt%, for example, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%. Preferably, the amount of the solution containing a soluble compound of Ce is such that the content of CeO2 in the catalyst obtained is 1-6wt%, more preferably 2-4wt%.

[0090] 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.

[0091] Preferably, the second calcination method includes: first heating the temperature to 100-150°C at a heating rate of 3-6°C / min, for example, it can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, etc., and then heating the temperature to 200-250°C at a heating rate of 0.2-0.6°C / min, for example, it can be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, etc., and then heating the temperature to the calcination temperature at a heating rate of 3-6°C / min for constant temperature.

[0092] In the present invention, a second drying process may be further included before the second calcination. The conditions of the second drying process include: a temperature of 80-120° C. and a time of 8-48 hours.

[0093] In the present invention, preferably, the product obtained by contacting in step (3) is directly subjected to a second calcination (if a second drying is also included, the second drying and the second calcination are directly performed).

[0094] The third aspect of the present invention provides use of the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect in a methane-carbon dioxide reforming reaction.

[0095] A fourth aspect of the present invention provides a method for methane carbon dioxide reforming reaction, comprising: under reforming reaction conditions, contacting methane and carbon dioxide with a catalyst, wherein the catalyst is the catalyst described in the first aspect or the catalyst prepared by the preparation method described in the second aspect.

[0096] 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°C, preferably 750-850°C, more preferably 780-800°C; 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 10,000-30,000 h -1 , preferably 15000-25000h -1 , more preferably 18000-22000h -1 .

[0097] According to some preferred embodiments of the present invention, the method further comprises: reducing the catalyst under a hydrogen atmosphere before the contacting.

[0098] Preferably, the reduction conditions include: temperature of 400-600° C., preferably 400-550° C.; time of 1-20 h, preferably 2-6 h; and pressure of 0.1-0.5 MPa, preferably 0.2-0.3 MPa.

[0099] The present invention will be described in detail below through examples.

[0100] In the following examples, unless otherwise specified, the raw materials used were commercially available.

[0101] The MCM-41 molecular sieve used in the following examples is an all-silicon molecular sieve with an average pore size of 6 nm.

[0102] X-ray diffraction (XRD) tests were performed on an X'Pert3 Powder diffractometer using a Cu Kα target (incident wavelength ), the scanning range was 0-90°, and the scanning speed was 10° / min.

[0103] The crystal phase analysis of the samples was carried out on a Philips PW1710 X-ray diffractometer with a Cu target, a Kα radiation source, a tube voltage of 40 kV, a tube current of 30 mA, a scanning step of 0.02°, a scanning speed of 1.2° / min, and a scanning range of 2θ = 1-10°.

[0104] 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 raised to 150°C at a rate of 10°C / min in an N2 atmosphere, maintained for 30 minutes, and then cooled to room temperature. The gas was switched to a 5% H2-95% N2 atmosphere, and the temperature was raised to 900°C at a heating rate of 10°C / min. The tail gas was detected by TCD. The reduction degree of the sample was calibrated by the hydrogen consumption required for the in-situ reduction of CuO.

[0105] The composition of the catalyst was analyzed by X-ray fluorescence spectrometry (XRF, EAGLE III, EDAX Inc.) by performing a full element scan on the catalyst to analyze the elemental composition and content of each element.

[0106] The average particle size of Ni is tested by reducing the catalyst at 450°C for 2 hours under hydrogen atmosphere and then testing it by XRD 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, and then it is calculated by Scherrer formula.

[0107] The carbon deposit content of the catalyst after the reaction was characterized by TGA. Thermal analysis was performed on a thermogravimetric (SETSYS Evolution, SETARAM) connected to a mass spectrometer (Hider, England) from Perkin Elmer, USA, with a heating rate of 10 °C min -1 The test was carried out in air atmosphere with a gas flow rate of 30 mL min -1 , the measurement temperature range is from room temperature to 900℃.

[0108] Example 1

[0109] 68.8 g of citric acid was dissolved in 258 mL of water and stirred at 80°C for 30 minutes to completely dissolve the citric acid. 155 g of La(NO₃)₃·6H₂O and 104 g of Ni(NO₃)₂·6H₂O were added to the citric acid solution and stirred at 80°C for 1 hour. 2 g of MgO and 10 g of commercially available MCM-41 molecular sieve were added to the solution and stirred at 80°C for 8 hours to form a gel. The gel was then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min to obtain a semi-finished catalyst. The composition of the semi-finished catalyst was determined by XRF analysis and is shown in Table 1.

[0110] Then, 40g of ethanol, 4g of PEG400 and 0.4g of span80 were mixed respectively, 8.4g of Ce(NO3)3·6H2O was dissolved in the above mixed solution, and then 80g of the catalyst semi-finished solid was impregnated with the solution containing Ce(NO3)3·6H2O for 8h. After the impregnation was completed, it was directly placed in an oven at 100°C for drying, and then placed in a muffle furnace for calcination. The muffle furnace heating method was: between 50°C-120°C, the heating rate was 5°C / min, the heating rate between 120°C-220°C was 0.5°C / min, and the heating rate between 220-450°C was 5°C / min. Then, the catalyst CAT-1 was calcined at 450°C for 4h.

[0111] The composition of the catalyst is shown in Table 1.

[0112] The above catalyst was subjected to X-ray diffraction (XRD) testing. The XRD spectrum is shown in Figure 1, which shows that the catalyst has diffraction peaks at 2θ of 28.0°, 31.2°, and 32.7°, proving that a perovskite LaNiO3 structure and a perovskite-like La2NiO4 structure are formed in the catalyst, and CeO2 is present.

[0113] The crystal phase analysis results of the sample are shown in FIG2 , which show obvious characteristic peaks of MCM-41, proving that the catalyst contains MCM-41 molecular sieve.

[0114] The above catalyst was subjected to H2-TPR test. The results are shown in Figures 3 and 4. The catalyst has two reduction peaks at 354 and 385°C.

[0115] Example 2

[0116] Dissolve 68.8g of citric acid in 258mL of water and stir at 80°C for 30 minutes to completely dissolve the citric acid. Add 158g of La(NO3)3·6H2O and 106g of Ni(NO3)2·6H2O to the citric acid solution and stir at 80°C for 1 hour. Add 1g of MgO and 9g of commercially available MCM-41 molecular sieve to the solution and stir at 80°C for 8 hours to form a gel. The gel is then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min to obtain a solid catalyst semi-finished product. Take 10g of ethanol, 1.9g of PEG200 and 0.3g of span60 respectively and mix them, dissolve 2g of Ce(NO3)3·6H2O in the above mixed solution, and then use the solution containing Ce(NO3)3·6H2O to impregnate 80g of the catalyst semi-finished solid for 8h. After the impregnation is completed, put it directly into an oven at 120℃ for drying, and then put it into a muffle furnace for calcination. The muffle furnace heating method is: between 50℃-120℃, the heating rate is 5℃ / min, the heating rate between 120℃-220℃ is 0.5℃ / min, and the heating rate between 220-450℃ is 5℃ / min. Then, calcine at 450℃ for 4h to obtain catalyst CAT-2.

[0117] The composition of the catalyst is shown in Table 1.

[0118] The above catalyst was subjected to X-ray diffraction (XRD) testing. The XRD spectrum is shown in Figure 1, which shows that the catalyst has diffraction peaks at 2θ of 28.1°, 31.4°, and 32.9°, proving that a perovskite LaNiO3 structure and a perovskite-like La2NiO4 structure are formed in the catalyst, and CeO2 is present.

[0119] The above catalyst was subjected to H2-TPR test. The results are shown in FIG3 . The catalyst had two reduction peaks at 354° C. and 389° C.

[0120] Example 3

[0121] Dissolve 68.8g of citric acid in 258mL of water and stir at 80°C for 30 minutes to completely dissolve the citric acid. Add 151.4g of La(NO3)3·6H2O and 101.7g of Ni(NO3)2·6H2O to the citric acid solution and stir at 80°C for 1 hour. Add 3g of MgO and 11g of commercially available MCM-41 molecular sieves to the solution and stir at 80°C for 8 hours to form a gel. The gel is then dried at 100°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min to obtain a solid catalyst semi-finished product.

[0122] Take 129g of ethanol, 29.4g of AEO-8 and 5.8g of span40 respectively and mix them, dissolve 12.9g of Ce(NO3)3·6H2O in the above mixed solution, and then impregnate 80g of the catalyst semi-finished solid with the solution containing Ce(NO3)3·6H2O for 8h. After the impregnation is completed, put it directly into an oven at 100℃ for drying, and then put it into a muffle furnace for calcination. The muffle furnace heating method is: between 50℃-120℃, the heating rate is 5℃ / min, the heating rate between 120℃-220℃ is 0.5℃ / min, and the heating rate between 220-450℃ is 5℃ / min. Then, calcine at 450℃ for 4h to obtain catalyst CAT-3.

[0123] The composition of the catalyst is shown in Table 1.

[0124] The above catalyst was subjected to X-ray diffraction (XRD) testing. The XRD spectrum is shown in Figure 1, which shows that the catalyst has diffraction peaks at 2θ of 28.0°, 31.3°, and 32.7°, proving that a perovskite LaNiO3 structure and a perovskite-like La2NiO4 structure are formed in the catalyst, and CeO2 is present.

[0125] The above catalyst was subjected to H2-TPR test. The results are shown in FIG3 . The catalyst has two reduction peaks at 366° C. and 386° C.

[0126] Example 4

[0127] Dissolve 68.8g of citric acid in 258mL of water and stir at 80°C for 30 minutes to completely dissolve the citric acid. Add 155g of La(NO3)3·6H2O and 104g of Ni(NO3)2·6H2O to the citric acid solution and stir at 80°C for 1 hour. Add 2g of MgO and 10g of commercially available MCM-41 molecular sieve to the solution and stir at 80°C for 8 hours to form a gel. The gel is then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min. This yields a solid catalyst semi-finished product.

[0128] Take 260g of ethanol, 65g of PEG400 and 6.5g of span80 respectively and mix them, dissolve 50.5g of Ce(NO3)3·6H2O in the above mixed solution, and then impregnate 80g of the catalyst semi-finished solid with the solution containing Ce(NO3)3·6H2O for 8h. After the impregnation is completed, put it directly into an oven at 100℃ for drying, and then put it into a muffle furnace for calcination. The muffle furnace heating method is: between 50℃-120℃, the heating rate is 5℃ / min, the heating rate between 120℃-220℃ is 0.5℃ / min, and the heating rate between 220-450℃ is 5℃ / min. Then, calcine at 450℃ for 4h to obtain catalyst CAT-4.

[0129] The composition of the catalyst is shown in Table 1.

[0130] The above catalyst was subjected to X-ray diffraction (XRD) testing. The XRD spectrum is shown in Figure 1, which shows that the catalyst has diffraction peaks at 2θ of 28.0°, 31.2°, and 32.7°, proving that a perovskite LaNiO3 structure and a perovskite-like La2NiO4 structure are formed in the catalyst, and CeO2 is present.

[0131] The above catalyst was subjected to H2-TPR test. The results are shown in FIG3 . The catalyst has a reduction peak at 390° C.

[0132] Example 5

[0133] Dissolve 70.3 g of citric acid in 264 mL of water and stir at 80°C for 30 minutes to completely dissolve the citric acid. Add 158.5 g of La(NO₃)₃·6H₂O and 106.5 g of Ni(NO₃)₂·6H₂O to the citric acid solution and stir at 80°C for 1 hour. Add 10 g of commercially available MCM-41 molecular sieve to the solution and stir at 80°C for 8 hours to form a gel. The gel is then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min. This yields a solid catalyst semi-finished product.

[0134] Take 40g of ethanol, 4g of PEG400 and 0.4g of span80 respectively and mix them, dissolve 8.4g of Ce(NO3)3·6H2O in the above mixed solution, and then impregnate 80g of the catalyst semi-finished solid with the solution containing Ce(NO3)3·6H2O for 8h. After the impregnation is completed, put it directly into an oven at 100℃ for drying, and then put it into a muffle furnace for calcination. The muffle furnace heating method is: between 50℃-120℃, the heating rate is 5℃ / min, the heating rate between 120℃-220℃ is 0.5℃ / min, and the heating rate between 220-450℃ is 5℃ / min. Then, calcine at 450℃ for 4h to obtain catalyst CAT-5.

[0135] The composition of the catalyst is shown in Table 1.

[0136] The catalyst was subjected to X-ray diffraction (XRD) testing, and the XRD spectrum was similar to that of Example 1 in Figure 1. The catalyst was subjected to H2-TPR testing, which showed that the catalyst had a reduction peak at 355°C and a reduction peak at 386°C.

[0137] Example 6

[0138] Dissolve 76.5g of citric acid in 286.6mL of water and stir at 80°C for 30 minutes to completely dissolve the citric acid. Add 172.3g of La(NO3)3·6H2O and 115.8g of Ni(NO3)2·6H2O to the citric acid solution and stir at 80°C for 1 hour. Add 2g of commercially available MgO to the solution and stir at 80°C for 8 hours to form a gel. The gel is then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min. This yields a solid catalyst semi-finished product.

[0139] Take 40g of ethanol, 4g of PEG400 and 0.4g of span80 respectively and mix them, dissolve 8.4g of Ce(NO3)3·6H2O in the above mixed solution, and then impregnate 80g of the catalyst semi-finished solid with the solution containing Ce(NO3)3·6H2O for 8h. After the impregnation is completed, put it directly into an oven at 100℃ for drying, and then put it into a muffle furnace for calcination. The muffle furnace heating method is: between 50℃-120℃, the heating rate is 5℃ / min, the heating rate between 120℃-220℃ is 0.5℃ / min, and the heating rate between 220-450℃ is 5℃ / min. Then, calcine at 450℃ for 4h to obtain catalyst CAT-6.

[0140] The composition of the catalyst is shown in Table 1.

[0141] The catalyst was subjected to X-ray diffraction (XRD) testing, and the XRD pattern was similar to that of Example 1 in Figure 1. The catalyst was subjected to H2-TPR testing, as shown in Figure 3, which showed that the catalyst had two reduction peaks at 352°C and 382°C.

[0142] Example 7

[0143] Dissolve 78.1 g of citric acid in 293 mL of water and stir at 80°C for 30 minutes to completely dissolve the citric acid. Add 176 g of La(NO₃)₃·6H₂O and 118.3 g of Ni(NO₃)₂·6H₂O to the citric acid solution and stir at 80°C for 9 hours to form a gel. The gel is then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min. This yields a solid catalyst semi-finished product.

[0144] Take 40g of ethanol, 4g of PEG400 and 0.4g of span80 respectively and mix them, dissolve 8.4g of Ce(NO3)3·6H2O in the above mixed solution, and then impregnate 80g of the catalyst semi-finished solid with the solution containing Ce(NO3)3·6H2O for 8h. After the impregnation is completed, put it directly into an oven at 100℃ for drying, and then put it into a muffle furnace for calcination. The muffle furnace heating method is: between 50℃-120℃, the heating rate is 5℃ / min, the heating rate between 120℃-220℃ is 0.5℃ / min, and the heating rate between 220-450℃ is 5℃ / min. Then, calcine at 450℃ for 4h to obtain catalyst CAT-7.

[0145] The composition of the catalyst is shown in Table 1.

[0146] The catalyst was subjected to X-ray diffraction (XRD) testing, and the XRD spectrum was similar to that of Example 1 in Figure 1. The catalyst was subjected to H2-TPR testing, which showed that the catalyst had two reduction peaks at 356°C and 392°C.

[0147] Example 8

[0148] Dissolve 68.8g of citric acid in 258mL of water and stir at 80°C for 30 minutes to completely dissolve the citric acid. Add 155g of La(NO3)3·6H2O and 104g of Ni(NO3)2·6H2O to the citric acid solution and stir at 80°C for 1 hour. Add 2g of MgO and 10g of commercially available MCM-41 molecular sieve to the solution and stir at 80°C for 8 hours to form a gel. The gel is then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min. This yields a solid catalyst semi-finished product.

[0149] Take 40g of ethanol, 4g of PEG400 and 0.4g of span80 respectively and mix them, dissolve 8.4g of Ce(NO3)3·6H2O in the above mixed solution, and then impregnate 80g of the catalyst semi-finished solid with the solution containing Ce(NO3)3·6H2O for 8h. After the impregnation is completed, put it directly into an oven at 100℃ for drying, and then put it into a muffle furnace for calcination. The muffle furnace heating method is between 50℃-450℃, the heating rate is 5℃ / min, and the catalyst CAT-8 is obtained by calcining at 450℃ for 4h.

[0150] The composition of the catalyst is shown in Table 1.

[0151] The above catalyst was subjected to X-ray diffraction (XRD) testing, and the XRD spectrum showed that the catalyst had diffraction peaks at 2θ of 28.1°, 31.3°, and 32.8°, proving that perovskite LaNiO3 structure and perovskite-like La2NiO4 structure were formed in the catalyst, and CeO2 was present.

[0152] The above catalyst was subjected to H2-TPR test, which showed that the catalyst had a reduction peak at 390°C.

[0153] Comparative Example 1

[0154] 68.8 g of citric acid was dissolved in 258 mL of water and stirred at 80°C for 30 minutes to completely dissolve the citric acid. 155 g of La(NO₃)₃·6H₂O and 104 g of Ni(NO₃)₂·6H₂O were added to the citric acid solution and stirred at 80°C for 1 hour. 2 g of MgO and 10 g of commercially available MCM-41 molecular sieve were added to the solution and stirred at 80°C for 8 hours to form a gel. The gel was then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min. This yielded catalyst DCAT-1.

[0155] The composition of the catalyst is shown in Table 2. The H2-TPR test of the above catalyst showed that the catalyst had a reduction peak at 432°C and a reduction peak at 571°C.

[0156] Comparative Example 2

[0157] Dissolve 77.6 g of Ni(NO₃)₂·6H₂O in 192 g of water and impregnate 80 g of a commercially available SiO₂ support for 8 hours. The mixture is then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min. This yields a solid catalyst semi-finished product.

[0158] Take 40g of ethanol, 4g of PEG400 and 0.4g of span80 respectively and mix them, dissolve 8.4g of Ce(NO3)3·6H2O in the above mixed solution, and then impregnate 80g of the catalyst semi-finished solid with the solution containing Ce(NO3)3·6H2O for 8h. After the impregnation is completed, put it directly into an oven at 100℃ for drying, and then put it into a muffle furnace for calcination. The muffle furnace heating method is: between 50℃-120℃, the heating rate is 5℃ / min, the heating rate between 120℃-220℃ is 0.5℃ / min, and the heating rate between 220-450℃ is 5℃ / min. Then, calcine at 450℃ for 4h to obtain the catalyst DCAT-2.

[0159] The catalyst was subjected to H2-TPR testing, which showed that the catalyst had a reduction peak at 421°C. The composition of the catalyst is shown in Table 2. The crystal phase analysis spectrum of the catalyst sample is shown in Figure 2.

[0160] Comparative Example 3

[0161] Dissolve 77.6g of Ni(NO₃)₂·6H₂O in 192g of water and impregnate 80g of a commercially available Al₂O₃ support for 8 hours. The mixture is then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min. This yields a solid catalyst semi-finished product.

[0162] Take 40g of ethanol, 4g of PEG400 and 0.4g of span80 respectively and mix them, dissolve 8.4g of Ce(NO3)3·6H2O in the above mixed solution, and then impregnate 80g of the catalyst semi-finished solid with the solution containing Ce(NO3)3·6H2O for 8h. After the impregnation is completed, put it directly into an oven at 100℃ for drying, and then put it into a muffle furnace for calcination. The muffle furnace heating method is: between 50℃-120℃, the heating rate is 5℃ / min, the heating rate between 120℃-220℃ is 0.5℃ / min, and the heating rate between 220-450℃ is 5℃ / min. Then, calcine at 450℃ for 4h to obtain the catalyst DCAT-3.

[0163] The catalyst was subjected to H2-TPR testing, which showed that the catalyst had a reduction peak at 431° C. The composition of the catalyst is shown in Table 2.

[0164] Comparative Example 4

[0165] Dissolve 68.8g of citric acid in 258mL of water and stir at 80°C for 30 minutes to completely dissolve the citric acid. Add 155g of La(NO3)3·6H2O and 104g of Co(NO3)2·6H2O to the citric acid solution and stir at 80°C for 1 hour. Add 2g of MgO and 10g of commercially available MCM-41 molecular sieve to the solution and stir at 80°C for 8 hours to form a gel. The gel is then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min. This yields a solid catalyst semi-finished product.

[0166] Take 40g of ethanol, 4g of PEG400 and 0.4g of span80 respectively and mix them, dissolve 8.4g of Ce(NO3)3·6H2O in the above mixed solution, and then impregnate 80g of the catalyst semi-finished solid with the solution containing Ce(NO3)3·6H2O for 8h. After the impregnation is completed, put it directly into an oven at 100℃ for drying, and then put it into a muffle furnace for calcination. The muffle furnace heating method is: between 50℃-120℃, the heating rate is 5℃ / min, the heating rate between 120℃-220℃ is 0.5℃ / min, and the heating rate between 220-450℃ is 5℃ / min. Then, calcine at 450℃ for 4h to obtain the catalyst DCAT-4.

[0167] The catalyst was subjected to H2-TPR testing, which showed that the catalyst had a reduction peak in the range of 410-430° C. The composition of the catalyst is shown in Table 2.

[0168] Comparative Example 5

[0169] Dissolve 77.6 g of Ni(NO₃)₂·6H₂O in 192 g of water and impregnate 80 g of a commercially available MCM-41 support for 8 hours. The mixture is then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min. This yields a solid catalyst semi-finished product.

[0170] Take 40g of ethanol, 4g of PEG400 and 0.4g of span80 respectively and mix them, dissolve 8.4g of Ce(NO3)3·6H2O in the above mixed solution, and then impregnate 80g of the catalyst semi-finished solid with the solution containing Ce(NO3)3·6H2O for 8h. After the impregnation is completed, put it directly into an oven at 100℃ for drying, and then put it into a muffle furnace for calcination. The muffle furnace heating method is: between 50℃-120℃, the heating rate is 5℃ / min, the heating rate between 120℃-220℃ is 0.5℃ / min, and the heating rate between 220-450℃ is 5℃ / min. Then, calcine at 450℃ for 4h to obtain the catalyst DCAT-5.

[0171] The catalyst was subjected to H2-TPR testing, which showed that the catalyst had a reduction peak at 425°C. The composition of the catalyst is shown in Table 2.

[0172] Comparative Example 6

[0173] Dissolve 78.1 g of citric acid in 293 mL of water and stir at 80°C for 30 minutes to completely dissolve the citric acid. Add 176 g of La(NO₃)₃·6H₂O and 118.3 g of Ni(NO₃)₂·6H₂O to the citric acid solution and stir at 80°C for 9 hours to form a gel. The gel is then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min. This yields catalyst DCAT-6.

[0174] The composition of the catalyst is shown in Table 2.

[0175] The catalyst was subjected to an X-ray diffraction (XRD) test, as shown in FIG1 , which showed that the phase of the catalyst was mainly a perovskite LaNiO 3 phase.

[0176] The above catalyst was subjected to H2-TPR test, which showed that the catalyst had three reduction peaks in the range of 400-650°C.

[0177] Comparative Example 7

[0178] 77.6 g of Ni(NO₃)₂·6H₂O was dissolved in 192 g of water and impregnated onto 80 g of a commercially available CeO₂ support for 8 hours. The mixture was then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min. This yielded catalyst DCAT-7.

[0179] The composition of the catalyst is shown in Table 2.

[0180] The above catalyst was subjected to X-ray diffraction (XRD) testing. As shown in FIG1 , the phase of the catalyst was mainly CeO 2 phase.

[0181] The above catalyst was subjected to H2-TPR test, which showed that the catalyst had two reduction peaks in the range of 410-480°C.

[0182] Comparative Example 8

[0183] Dissolve 68.8g of citric acid in 258mL of water and stir at 80°C for 30 minutes to completely dissolve the citric acid. Add 155g of La(NO3)3·6H2O and 104g of Ni(NO3)2·6H2O to the citric acid solution and stir at 80°C for 1 hour. Add 2g of MgO and 10g of commercially available MCM-41 molecular sieve to the solution and stir at 80°C for 8 hours to form a gel. The gel is then dried at 110°C and calcined at 650°C for 6 hours at a heating rate of 5°C / min. This yields a solid catalyst semi-finished product.

[0184] Take 40g of water and dissolve 8.4g of Ce(NO3)3·6H2O in the above mixed solution. Then, use the solution containing Ce(NO3)3·6H2O to impregnate 80g of the catalyst semi-finished solid for 8h. After the impregnation is completed, directly put it into an oven at 100℃ for drying, and then put it into a muffle furnace for calcination. The muffle furnace heating method is: between 50℃-120℃, the heating rate is 5℃ / min, the heating rate between 120℃-220℃ is 0.5℃ / min, and the heating rate between 220-450℃ is 5℃ / min. Then, calcine at 450℃ for 4h to obtain the catalyst DCAT-8.

[0185] The composition of the catalyst is shown in Table 2.

[0186] The above catalyst was subjected to X-ray diffraction (XRD) testing, and no characteristic peak of La2NiO4 was found.

[0187] The above catalyst was subjected to H2-TPR test, as shown in Figure 4, which showed that a large amount of high-temperature reduced nickel species existed above 400°C.

[0188] Table 1 Note: In the above table, the CeO2 content is based on the total amount of the catalyst, and the content of the auxiliary element and molecular sieve is based on the mass of the semi-finished catalyst.

[0189] Table 2 Note: In the above table, the CeO2 content is based on the total amount of the catalyst, and the content of the auxiliary element and molecular sieve is based on the mass of the semi-finished catalyst.

[0190] Test Case

[0191] The catalysts in the above examples and comparative examples were evaluated in a methane-carbon dioxide reforming reaction.

[0192] The catalyst was first reduced at 450°C and a hydrogen pressure of 0.3 MPa for 4 h, and then subjected to a methane-carbon dioxide reforming reaction. The reaction conditions included: a molar ratio of methane to carbon dioxide of 1:1.2, a reaction temperature of 800°C, a pressure of 0.3 MPa, and a total space velocity of the feed gas of 20,000 h -1 After 96 h of reaction, the product was collected and its composition was analyzed by gas chromatography. The CO2 conversion rate and CH4 conversion rate were calculated. The carbon deposition amount of the catalyst was tested by thermogravimetric method under air atmosphere. The results are shown in Table 3.

[0193] The stability of the catalysts of Examples 1, 6 and Comparative Example 1 was evaluated under the same conditions as above. The results of the CO2 conversion rate change after 500 hours of continuous reaction are shown in FIG5 .

[0194] Table 3

[0195] The results in Table 3 demonstrate that the catalysts prepared using the examples provided herein exhibit high CO2 and CH4 conversion rates after 96 hours of reaction, with low carbon deposits. Thermogravimetric loss plots of the catalysts from Examples 1 and 6 and Comparative Example 6 in an oxygen atmosphere after 100 hours of reaction are shown in Figure 6, demonstrating the catalysts provided herein exhibit strong resistance to carbon deposition and excellent stability.

[0196] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection 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 having a perovskite structure; the catalyst has diffraction peaks at 2θ of 32.7±0.3°, 31.3±0.3°, and 28.0±0.3° as measured by X-ray diffraction; The catalyst has at least one reduction peak below 400 °C as measured by H2-TPR; Based on the total amount of the catalyst, the content of CeO2 is 1-20wt%.

2. The catalyst according to claim 1, wherein After the catalyst is reduced at 450° C. for 2 hours in a hydrogen atmosphere, the average particle size of Ni measured by X-ray diffraction is 13-22 nm, preferably 15-18 nm; Preferably, as measured by H2-TPR, the catalyst has at least one reduction peak at 350-390°C, and preferably, the catalyst has at least two reduction peaks at 350-390°C.

3. The catalyst according to claim 1 or 2, wherein Based on the total amount of the catalyst, the content of CeO2 is 1-6wt%, preferably 2-4wt%; Preferably, according to XPS characterization, the molar ratio of Ni element to Ce element in the catalyst is (1-20):1, preferably (2-15):

1.

4. The catalyst according to any one of claims 1 to 3, wherein The Ni element in the La-Ni based oxide having a perovskite structure includes divalent nickel and trivalent nickel; Preferably, the area of ​​the characteristic peak of the catalyst at 2θ of 32.7±0.3° is S1, the peak area of ​​the diffraction peak at 2θ of 31.3±0.3° is S2, and S2 / S1 is (0.5-1.5):1, preferably (1.1-1.4):

1.

5. The catalyst according to any one of claims 1 to 4, wherein XPS characterization shows that the molar ratio of Ni element to La element in the catalyst is (1.5-2.5):1, preferably (1.8-2.2):

1.

6. The catalyst according to claim 5, wherein The active matrix further includes an auxiliary element, which is selected from at least one of alkaline earth metals, preferably at least one of Mg, Ca and Sr, and more preferably Mg; Preferably, based on the total mass of the active matrix, the content of the auxiliary element in terms of oxide is 1-5 wt %, preferably 1.5-3 wt %.

7. The catalyst according to any one of claims 1 to 6, wherein The catalyst also includes molecular sieves.

8. The catalyst according to claim 7, wherein Based on the total mass of the active matrix, the content of the molecular sieve calculated as silicon dioxide is 5-15 wt %, preferably 9-11 wt %.

9. The catalyst according to claim 7 or 8, wherein The molecular sieve is an all-silica mesoporous molecular sieve, preferably at least one of MCM-41, SBA-15, MCM-48 and SBA-16 molecular sieves, more preferably MCM-41 molecular sieve.

10. A method for preparing a catalyst, characterized in that: The following steps are involved: (1) mixing a La source, a Ni source and a solvent in the presence of a complexing agent to obtain a mixture; (2) reacting the mixture to form a gel, and then performing a first calcination to obtain a semi-finished catalyst; (3) contacting a solution containing a soluble compound of Ce with the semi-finished catalyst in the presence of a surfactant, and then performing a second calcination; Wherein, the surfactant includes polyoxyethylene nonionic surfactant and polyol nonionic surfactant.

11. The preparation method according to claim 10, wherein: In step (1), the molar ratio of the Ni source to the La source, calculated as metal elements, is (0.5-2):1, preferably (0.5-1.5):1; Preferably, the molar ratio of the total molar amount of the La source and the Ni source calculated as metal elements to the complexing agent is 0.5-3:

1.

12. The preparation method according to claim 11, wherein The mixture also includes an auxiliary element precursor, wherein the auxiliary element is at least one of alkaline earth metals, preferably at least one selected from Mg, Ca and Sr, more preferably Mg; Preferably, the amount of the auxiliary element precursor is such that the content of the auxiliary element in the semi-finished catalyst calculated as oxide is 1-5wt%, preferably 1.5-3wt%.

13. The preparation method according to any one of claims 10 to 12, wherein: In step (2), the reaction conditions include: temperature of 50-100°C, preferably 60-90°C, time of 1-12h, preferably 6-8h; Preferably, the first calcination conditions include: temperature of 300-1200° C. and time of 2-20 h.

14. The preparation method according to any one of claims 10 to 13, wherein: 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; Preferably, the polyol nonionic surfactant is a sorbitan fatty acid ester, preferably at least one of sorbitan monopalmitate, sorbitan monooleate and sorbitan monostearate; Preferably, the mass ratio of the polyoxyethylene nonionic surfactant to the polyol nonionic surfactant is 1:(0.1-1), preferably 1:(0.1-0.5).

15. The preparation method according to any one of claims 10 to 14, wherein: The mass ratio of the Ce soluble compound calculated as CeO2 to the surfactant is 1:(1-10), preferably 1:(1-8); Preferably, the amount of the solution containing the soluble compound of Ce is such that the content of CeO2 in the prepared catalyst is 1-20wt%, preferably 1-6wt%, more preferably 2-4wt%.

16. The preparation method according to any one of claims 10 to 15, wherein: The second calcination conditions include: calcination temperature of 400-600°C, constant temperature time of 2-6h; 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.

17. The preparation method according to any one of claims 10 to 16, wherein: In step (1), the mixture also includes molecular sieves; Preferably, the molecular sieve is used in an amount such that the content of the molecular sieve in the semi-finished catalyst calculated as silicon dioxide is 5-15 wt%, preferably 9-11 wt%.

18. The preparation method according to claim 17, wherein: The molecular sieve is an all-silicon mesoporous molecular sieve, preferably at least one selected from MCM-41, SBA-15, MCM-48 and SBA-16 molecular sieves, more preferably MCM-41 molecular sieve; Preferably, the average pore size of the molecular sieve is 1-15 nm.

19. Use of the catalyst according to any one of claims 1 to 9 or the catalyst prepared by the preparation method according to any one of claims 10 to 18 in methane carbon dioxide reforming reaction.

20. 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 described in any one of claims 1 to 9 or the catalyst prepared by the preparation method described in any one of claims 10 to 18.

21. The method according to claim 20, wherein: 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°C, preferably 750-850°C, more preferably 780-800°C; a pressure of 0.1-1MPa, preferably 0.1-0.5MPa, more preferably 0.2-0.4MPa, and a total space velocity of the feed gas of 10000-30000h -1 , preferably 15000-25000h -1 , more preferably 18000-22000h -1 .

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