Methane reforming catalyst with high carbon deposition resistance as well as preparation method and application of methane reforming catalyst

Abstract

The invention discloses a methane reforming catalyst with high carbon deposition resistance and a preparation method and application thereof, the catalyst comprises a multi-metal alloy active phase, a cerium oxide auxiliary phase rich in oxygen vacancies and a composite porous calcium magnesium aluminate carrier phase, and the preparation method comprises carrier forming maintenance, step-by-step compounding and the like. The performance advantages of metal nickel, cobalt, ruthenium and yttrium are fully utilized, and the carbon deposition resistance of the catalyst is remarkably improved; the auxiliary phase and the carrier phase are used for further supplementing active sites required by the reaction, so that metal-carrier interaction with moderate strength is formed, and ideal reaction efficiency is ensured; direct molding is performed in the preparation process, so that adverse effects of molding treatment on the structure and performance of the catalyst are greatly avoided. The catalyst provided by the invention is strong in carbon deposition resistance, good in thermal stability and high in mechanical strength, can be used in a high-temperature and high-pressure environment of reforming reaction for a long time, and has a wide industrial application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of industrial catalysis, and particularly relates to a high-anti-coking methane reforming catalyst as well as a preparation method and application thereof. BACKGROUND

[0002] A methane reforming process converts methane into syngas (CO and H2) through high-temperature catalytic reaction, which can be divided into steam methane reforming (SMR), dry reforming of methane (DRM), partial oxidation reforming of methane (POM), etc. It has strategic significance for improving resource utilization efficiency and energy security, promoting hydrogen energy economy and energy transformation, and driving carbon neutralization and environmental governance. It has been listed as an encouraged project in the petrochemical industry by the National Development and Reform Commission.

[0003] Among the many key technical links of methane reforming, catalysts have attracted much attention. At present, nickel-based catalysts are mainly used in methane reforming, but they have the disadvantages of easy carbon deposition and easy sintering, and have high requirements for feed ratios. When the steam content decreases and the carbon dioxide content increases, the performance stability of the catalysts deteriorates significantly. In contrast, although noble metal and nano-structured catalysts can alleviate the problem of carbon deposition to some extent, they are difficult to control in terms of cost and have complex preparation processes, which greatly restricts their industrialization and application.

[0004] In order to solve the problem of carbon deposition on methane reforming catalyst, researchers have provided many technical solutions. In the prior art, CN 115282970 A discloses a nickel-based catalyst for dry reforming of low-carbon alkanes limited by oxide film and its preparation method and use. The high dispersion and high thermal stability of nickel active sites are realized by the oxide film limited structure, mainly solving the dispersion problem of active nickel. The preparation process includes sublimation and deposition of fluorides, and the scale-up difficulty is high. CN 118996498 A discloses a nickel-cobalt co-doped ruthenium-based metal nanoparticle catalyst and its preparation method and application. The catalyst nanoparticles are prepared by co-precipitation of metal ruthenium salt, nickel salt and cobalt salt in an alkaline solution and hydrothermal treatment. However, the precipitation curves of ruthenium ions, nickel ions and cobalt ions differ, making it difficult to accurately control the doping ratio. CN 119186634 A discloses a preparation method of a methane dry reforming supported nickel-based catalyst. Nickel is loaded on a clinoptilolite carrier, but it is difficult to avoid the migration and agglomeration of nickel in the zeolite structure after a long time of reaction. CN 117983278 A discloses a high-anti-coking methane dry gas reforming reaction composite catalyst and its application. The catalyst is composed of three components: supported nickel-based catalyst, nitrogen-doped carbon-supported molybdenum catalyst and inert carrier. The catalyst preparation is difficult. CN 118594547 A discloses a surfactant-modified hydrotalcite-derived nickel-based catalyst and its preparation and application. Nickel oxide is loaded on a magnesium-aluminum composite oxide of hydrotalcite precursor, showing certain confinement effect, but the long-term performance stability needs further verification. CN 107921427 A discloses a catalyst with nickel and cerium core-shell structure for methane dry reforming reaction, which has high activity and coking resistance. However, the catalyst needs to have a core-shell structure and active metal deposited on the surface of the shell. It is difficult to ensure the integrity of the shell layer during large-scale production, which may lead to uneven product quality.

[0005] In summary, there is an urgent need to develop a new type of high-anti-coking methane reforming catalyst and its preparation method to solve the problems of catalyst easy carbon deposition and lack of fine control of active sites in the prior art. SUMMARY

[0006] The purpose of the present application is to provide a high-anti-coking methane reforming catalyst and its preparation method to solve the problem of catalyst easy carbon deposition during reforming reaction in the prior art and suitable for large-scale production.

[0007] To achieve the above invention purposes, the technical solutions of the present application are as follows:

[0008] A high-anti-coking methane reforming catalyst, comprising the following components: active phase, additive phase and carrier phase; wherein the active phase is a multi-metal alloy, the additive phase is cerium oxide rich in oxygen vacancies, and the carrier phase is a composite porous calcium-magnesium-aluminate.

[0009] A high anti-coking methane reforming catalyst having a volcano active phase and an auxiliary phase (as shown in the attached Figure 1 The present application relates to a high anti-coking methane reforming catalyst having a bimodal pore structure, a porosity not less than 12%, preferably 12%≤porosity≤30%; wherein the macropores with a pore size of 100 nm or more account for not less than 98%, including but not limited to 98.5%, 99%, 99.5%, 99.8% or a range consisting of any two of them; the meso-micropores with a pore size of 0.5-50 nm account for 0.1-2%, including but not limited to 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8% or a range consisting of any two of them.

[0010] In the scheme of the present application, the catalyst comprises the following mass percentage of each component in the form of elements contained therein: nickel 4-6%, including but not limited to 4.2%, 4.4%, 4.6%, 4.8%, 5.0%, 5.2%, 5.4%, 5.6%, 5.8%, or a range consisting of any two of them; cobalt 4-6%, including but not limited to 4.2%, 4.4%, 4.6%, 4.8%, 5.0%, 5.2%, 5.4%, 5.6%, 5.8%, or a range consisting of any two of them; ruthenium 0.1-3%, including but not limited to 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, or a range consisting of any two of them; yttrium 0-0.1%, including but not limited to 0.001%, 0.003%, 0.005%, 0.007%, 0.009%, 0.01%, 0.03%, 0.05%, 0.07%, 0.09%, or a range consisting of any two of them; cerium 4-10%, including but not limited to 4.5%, 5.0%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, or a range consisting of any two of them; calcium 8-15%, including but not limited to 8.5%, 9.0%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, or a range consisting of any two of them; magnesium 0.1-5%, including but not limited to 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or a range consisting of any two of them; aluminum 25-35%, including but not limited to 26%, 28%, 30%, 32%, 34%, or a range consisting of any two of them; oxygen 30-45%, including but not limited to 32%, 34%, 36%, 38%, 40%, 42%, 44%, or a range consisting of any two of them; based on the total mass of the elements contained in the catalyst in the form of elements, the total mass is 100%.

[0011] In the scheme of the present application, the active phase multi-metallic alloy is a nickel-cobalt-ruthenium-yttrium alloy nanoparticle or a nickel-cobalt-ruthenium alloy nanoparticle, with an average particle size ≤50 nm.

[0012] In the scheme of the present application, in the oxygen vacancy-rich cerium oxide of the auxiliary phase, the average valence of cerium is between +1.5 valence and +3 valence.

[0013] In the scheme of the present application, the specific surface area of the carrier phase composite porous calcium-magnesium-aluminate is not less than 20 m 2 / g, preferably the specific surface area is 20-60 m 2 / g, and the strength of the preform is not less than 300N / particle.

[0014] A preparation method of a high-anti-carbon-deposition methane reforming catalyst, comprising the following steps:

[0015] Step 1: uniformly mix solid powders containing calcium aluminate, magnesium-aluminum spinel and additives with water into a slurry, inject the slurry into a mold to form a blank with a target shape, and spray water on the blank to keep it wet multiple times.

[0016] Step 2: dry and calcine the blank, and after cooling to room temperature, screen out fine powder to obtain a granular catalyst carrier;

[0017] Step 3: uniformly mix cerium salt and ammonia water to prepare a mixed solution;

[0018] Step 4: stir the catalyst carrier in the mixed solution obtained in step 3, dry and calcine to obtain an intermediate catalyst;

[0019] Step 5: uniformly mix nickel salt, cobalt salt, ruthenium salt and optional yttrium salt with water to prepare a multi-component mixed solution;

[0020] Step 6: add the multi-component mixed solution to the intermediate catalyst until the saturation water absorption capacity is reached, and dry and calcine to obtain the catalyst.

[0021] As a preferred solution, the preparation method of the high-anti-carbon-deposition methane reforming catalyst comprises the following steps:

[0022] Step 1: uniformly mix solid powders containing calcium aluminate, calcium dialuminate, magnesium-aluminum spinel and additives with water into a slurry according to a proportion, inject the slurry into a mold to form a blank with a target shape, and after standing at a suitable temperature for a period of time, demold the blank and then regularly spray water on the blank to keep it wet;

[0023] Step 2: after repeating for several days, dry the blank and calcine it in a high-temperature environment; after the blank naturally cools to room temperature, screen out fine powder to obtain a granular catalyst carrier;

[0024] Step 3: take an appropriate amount of cerium salt and ammonia water, uniformly mix them with water to prepare a mixed solution;

[0025] Step 4: put the catalyst carrier obtained in step 2 into the mixed solution obtained in step 3, stir at a set temperature, and after the stirring is completed, collect the catalyst carrier; dry and calcine at a set temperature, and after the calcination is completed, naturally cool the catalyst carrier to room temperature, and collect an intermediate catalyst;

[0026] Step 5: uniformly mix an appropriate amount of nickel salt, cobalt salt, ruthenium salt and optional yttrium salt with water to prepare a multi-component mixed solution;

[0027] Step 6: slowly drop the multi-component mixed solution obtained in step 5 into the intermediate catalyst obtained in step 4 until the saturated water absorption amount is reached; dry and calcine at a set temperature, and after the end, naturally cool to room temperature, and collect the catalyst.

[0028] In the preparation method of the application, the calcium aluminate in step 1 is preferably calcium aluminate or dicalcium aluminate; the mass ratio of solid powder to water is 0.3-1.5, preferably 0.4-0.8, including but not limited to 0.5, 0.7, 0.9, 1.0, 1.2, 1.4 or a range consisting of any two of them; the slurry viscosity is 5-20 Pa·s, preferably 8-12 Pa·s, including but not limited to 6 Pa·s, 9 Pa·s, 10 Pa·s, 11 Pa·s, 13 Pa·s, 15 Pa·s, 17 Pa·s, 19 Pa·s or a range consisting of any two of them.

[0029] In the preparation method of the application, the additive in step 1 includes but is not limited to cellulose, polyvinyl alcohol, sodium dodecyl sulfate, rosin hot polymer, triterpene saponin, etc., and the addition amount is not higher than 10wt%, preferably the addition amount is 0.5wt%-10wt% based on the total mass of calcium aluminate, dicalcium aluminate and magnesium aluminate spinel solid powder.

[0030] Preferably, the shaped blank in step 1 needs to be placed for a period of time, preferably the standing temperature is 5-30℃, preferably 15-25℃, including but not limited to 5℃, 7℃, 9℃, 11℃, 15℃, 17℃, 19℃, 21℃, 25℃, 27℃, 29℃ or a range consisting of any two of them; the standing time is 3-8 hours, preferably 4-6 hours, including but not limited to 3.5, 5, 6.5, 7, 7.5 hours or a range consisting of any two of them.

[0031] In the preparation method of the application, the blank is sprayed with water multiple times in step 1, and the purpose is:

[0032] (1) continuously provide raw materials for hydration reaction and improve the strength of the blank;

[0033] (2) prevent the surface moisture of the blank from evaporating too fast, causing shrinkage cracking or cracking.

[0034] Preferably, the number of repeatable wetting days is 3-7 days, more preferably 4-5 days, and the water can be sprayed once every 4-7 hours, and the operation is repeated for 3-7 days.

[0035] In the preparation method of the application, the calcination temperature of the dried blank in step 2 is 300-600℃, preferably 450-500℃; the calcination time is 4-10 hours, preferably 6-8 hours; and the calcination atmosphere is air or inert atmosphere. The drying temperature is 5-40℃, preferably 15-25℃; and the drying time is 1-5 days, preferably 2-3 days.

[0036] In the preparation method of the application, the fine powder in step 2 is an unshaped carrier with a diameter less than 1mm.

[0037] In the preparation method of the application, the cerium salt in step 3 is a soluble salt of metallic cerium, including but not limited to cerium nitrate, cerium chloride, cerium sulfate, etc.; in the mixed solution, the concentration of cerium ions is 0.2-1mol / L, preferably 0.4-0.6mol / L, including but not limited to 0.3, 0.5, 0.7, 0.9mol / L or a range between any two of them; and the concentration of ammonium ions is 1.5-3mol / L, preferably 2-2.5mol / L, including but not limited to 1.6, 1.8, 1.9, 2, 2.5, 2.7mol / L or a range between any two of them.

[0038] In the preparation method of the application, the solid-liquid ratio of the catalyst carrier to the mixed solution in step 4 is 1:10-1:50, preferably 1:20-1:25, including but not limited to 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45 or a range between any two of them.

[0039] In the preparation method of the application, the stirring in step 4 is carried out at a temperature of 15-80℃, preferably 25-60℃, including but not limited to 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or a range between any two of them; and the stirring time is 4-24 hours, preferably 8-12 hours; including but not limited to 5, 7, 9, 11, 15, 18, 20, 22 hours or a range between any two of them.

[0040] In the preparation method of the application, the drying temperature in step 4 is 95-130℃, preferably 110-120℃, and the drying time is 6-18 hours, preferably 8-12 hours. The calcination temperature is 500-700℃, preferably 550-600℃, the calcination time is 4-10 hours, preferably 6-8 hours, and the calcination atmosphere is air or inert atmosphere.

[0041] In the preparation method of the application, the nickel salt, cobalt salt, ruthenium salt and yttrium salt in step 5 are soluble salts of each of them, including but not limited to nitrate, chloride, sulfate, etc.

[0042] In the preparation method of the present application, the total concentration of metal ions in the multi-component mixed solution in step 5 is 0.5-3 mol / L, preferably 0.8-1.5 mol / L, including but not limited to 1, 1.2, 1.5, 2, 2.2, 2.5, 2.7, 2.9 mol / L or a range formed by any two of them.

[0043] In the preparation method of the present application, the drying temperature in step 6 is 95-130°C, preferably 110-120°C, and the drying time is 6-18 hours, preferably 8-12 hours. The calcination temperature is 300-600°C, preferably 450-550°C, the calcination time is 2-10 hours, preferably 4-6 hours, and the calcination atmosphere is air or inert atmosphere.

[0044] The present application also provides the use of the high-anti-coking methane reforming catalyst, which needs to be activated before use, and is suitable for steam reforming of methane, carbon dioxide reforming of methane, autothermal reforming of methane, partial oxidation reforming of methane, and any combination thereof.

[0045] The use of a high-anti-coking methane reforming catalyst, the activation process comprising the following steps:

[0046] Step 1: Use inert gas to purge the catalyst bed until the outlet oxygen content meets the standard;

[0047] Step 2: Slowly heat to the activation starting temperature, gradually increase the reducing gas content and temperature to the target value in several times, and then maintain;

[0048] Step 3: After step 2 is completed, reduce the reducing gas content to zero with a fixed concentration gradient, maintain inert gas purging, and adjust the catalyst bed temperature to the reaction temperature;

[0049] As a preferred scheme, the activation process comprises the following steps:

[0050] S101: Control the catalyst bed temperature, use inert gas to purge the catalyst bed, until the outlet oxygen content meets the standard;

[0051] S102: Slowly increase the catalyst bed temperature to the activation starting temperature, and then increase the reducing gas content in the purge gas after the temperature is stable, and then stabilize for a period of time;

[0052] S103: Increase the temperature at a set heating rate, and then repeat S102 until the activation temperature and the reducing gas content reach the target value, and stabilize for a period of time;

[0053] S104: Gradually reduce the reducing gas content in the purge gas to zero with a fixed concentration gradient;

[0054] S105: Keep inert gas purging, adjust the temperature of the catalyst bed to the reaction temperature at a set temperature rate, and complete the catalyst activation process.

[0055] In the activation method of the present application, the oxygen content requirement in step 1 or S101 is not higher than 0.2%.

[0056] In the activation method of the present application, the activation starting temperature in step 2 or S102 is 200-350℃, preferably 250-300℃; including but not limited to 220℃, 240℃, 260℃, 280℃, 300℃, 320℃, 340℃, or a range consisting of any two of them; the reducing gas is hydrogen, the increase value of the reducing gas content each time is not more than 5% / time, preferably not more than 2% / time, more preferably the increase value of the reducing gas content each time is 0.5% / time-2% / time; the stabilization time is 0.2-2 hours after the bed temperature remains unchanged, preferably 0.5-1 hour, including but not limited to 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, or a range consisting of any two of them.

[0057] In the activation method of the present application, the set temperature rate in step 2 or S103 is 5-50℃ / hour, preferably 10-20℃ / hour; including but not limited to 8℃ / hour, 12℃ / hour, 16℃ / hour, 20℃ / hour, 25℃ / hour, 30℃ / hour, 35℃ / hour, 40℃ / hour, 45℃ / hour, or a range consisting of any two of them; the increase value of the catalyst bed temperature each time is not more than 80℃ / time, preferably not more than 50℃ / time, more preferably the increase value of the catalyst bed temperature each time is 10℃ / time-50℃ / time; the temperature target value is 550-850℃, preferably 650-800℃; including but not limited to 560℃, 600℃, 650℃, 700℃, 750℃, 800℃, 820℃, or a range consisting of any two of them; the target value of the reducing gas content is 20-100%, preferably 30-100%, including but not limited to 25%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, 90%, or a range consisting of any two of them.

[0058] In the activation method of the present application, the reduction gradient of the reducing gas content in step 3 or S104 or S105 is 5-20%, including but not limited to 7%, 9%, 12%, 15%, 17%, 19%, or a range consisting of any two of them; the temperature adjustment rate is not higher than 50℃ / hour, preferably not higher than 20℃ / hour, more preferably the temperature adjustment rate is 5℃ / hour-20℃ / hour.

[0059] The beneficial effects of the present application are:

[0060] (1) In the methane reforming reaction, metal nickel, cobalt, ruthenium and optional yttrium can all be active sites, however, there are some deficiencies: among them, metal nickel is low in price and has the strongest activity among non-noble metals, can catalyze methane molecule adsorption and dissociation and break C-H bond to generate intermediates such as *CH3, *CH2, *CH, *C, etc., but is easy to make methane dissociate too fast, if the intermediates (such as *C) are not reacted with water or carbon dioxide in time, carbon deposition is easy to form, leading to catalyst deactivation; metal cobalt is slightly higher in price, its methane activation energy is higher than that of nickel, and the activity is poor, which is manifested as lower raw material conversion rate under the same reaction conditions, but due to its slower catalytic C-H bond breaking rate, it can provide sufficient time for decarburization reaction, realize the dynamic balance of carbon deposition-decarburization, and thus improve the stability of the catalyst; metal ruthenium and yttrium are the most expensive, and the current industrial application is limited by cost factors, but they have very strong activity in catalyzing methane dissociation and carbon deposition decomposition, and can maintain good catalytic activity for a long time. In view of this, the present application constructs a composite catalyst system, fully utilizes the advantages of high reactivity of metal nickel, high stability of metal cobalt, and strong carbon elimination performance of metal ruthenium and yttrium, and by controlling the ratio and loading amount of nickel, cobalt, ruthenium and yttrium, the deficiencies of easy carbon deposition of metal nickel, low activity of metal cobalt, and high cost of metal ruthenium and yttrium are made up, and the anti-carbon deposition performance of the catalyst is significantly improved within an acceptable cost range.

[0061] (2) In the preparation method of the catalyst of the present application, the porous carrier phase is used as the basis for step-by-step compounding, the rich oxygen vacancies in the oxygen vacancy-rich cerium oxide of the auxiliary phase are used to promote the migration of oxygen species to the metal sites, accelerate the oxidation and elimination of *C, and inhibit carbon deposition; the calcium and magnesium components in the carrier phase are used as auxiliary basic sites to enhance the CO2 adsorption capacity and promote the dynamic elimination of carbon deposition by Boudouard reaction. Through the step-by-step compounding of the active phase, the auxiliary phase and the carrier phase, a moderate strength metal-carrier interaction is formed, which not only improves the catalytic performance of the active phase, but also avoids excessive electron transfer caused by too strong interaction, and thus ensures the ideal reaction efficiency.

[0062] (3) Anchoring the needs of industrial application, the catalyst is directly formed in the preparation process without the need for further tabletting, calcination and other forming treatments, which greatly avoids the influence of forming treatment on the structure and performance of the catalyst; in addition, the catalyst provided by the present application has high strength and good thermal stability, and can be used in high-temperature and high-pressure environment of reforming reaction for a long time, and significant progress has been made in the service life. BRIEF DESCRIPTION OF DRAWINGS

[0063] Figure 1 Schematic diagram of the microstructure of the catalyst prepared in Example 1

[0064] Figure 2 Scanning electron microscope photo of the catalyst prepared in Example 1

[0065] Figure 3Pore size distribution of catalyst 1 prepared for example 1 DETAILED DESCRIPTION

[0066] In order to facilitate the understanding of the present application, the present application will be further described below in conjunction with examples. It should be understood that the following examples are only for better understanding of the present application, and do not mean that the present application is limited to the following examples only.

[0067] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The term "and / or", where used herein, includes any and all combinations of one or more of the associated listed items.

[0068] Main raw material sources

[0069] Nickel nitrate, National Pharmaceutical Group Chemical Reagent Co., Ltd., purity 99%;

[0070] Cobalt nitrate, National Pharmaceutical Group Chemical Reagent Co., Ltd., purity 99%;

[0071] Ruthenium chloride, National Pharmaceutical Group Chemical Reagent Co., Ltd., purity 99%;

[0072] Cerium nitrate, National Pharmaceutical Group Chemical Reagent Co., Ltd., purity 99%;

[0073] Concentrated ammonia, National Pharmaceutical Group Chemical Reagent Co., Ltd., purity ≥ 25%;

[0074] Sodium dodecyl sulfate, National Pharmaceutical Group Chemical Reagent Co., Ltd., purity 99%;

[0075] CA-70 cement, Zhengzhou Dengfeng Melt Co., Ltd.;

[0076] Alpha phase alumina particles: Aluminum Corporation of China, Ltd. Shandong New Material Co., Ltd., purity ≥ 97%.

[0077] Main test methods

[0078] The chemical composition of the catalyst was tested by X-ray fluorescence spectrometer (PANalytical, EPSilon4); the micro-morphology was tested by scanning electron microscope (Zeiss, Sigma500); the BET specific surface area was calculated from the low-temperature nitrogen adsorption-desorption isotherm, which was tested by physical adsorption instrument (Belsorp, BSD-660M); the porosity and pore size distribution were tested by mercury porosimeter (Micromeritics, AutoPore IV); the mechanical strength of the catalyst was tested by digital particle strength tester (Jiangyan, KC-4B).

[0079] The catalyst reaction performance was tested by a fixed bed complete set pilot plant equipment, which was equipped with independent methane, steam, carbon dioxide and nitrogen gas paths. The shaped catalyst was crushed and sieved to 16-40 mesh. The reaction temperature was 800°C, the reaction pressure was 0.1 MPa, and the space velocity was 20000 h-1. -1 The tail gas was cooled and then detected in real time by an online gas chromatograph (Agilent, GC-7890B, equipped with a thermal conductivity detector and a hydrogen flame ionization detector) to calculate various performance parameters.

[0080] The calculation formula of the methane conversion rate (X CH4 ) is as follows:

[0081]

[0082] Wherein: X CH4 is the methane conversion rate, unit %; F total,out is the total flow rate of the outlet gas, unit Nm 3 / h; p CH4,out is the volume content of methane in the outlet gas, unit %; F CH4,in is the inlet methane gas flow rate, unit Nm 3 / h.

[0083] The carbon deposition amount of the catalyst after the reaction was detected by a thermal gravimetric analyzer (Metler, TGA / DSC1). The sample to be tested was first purged at 120°C under nitrogen atmosphere for 0.5 hours, and then heated to 800°C at a heating rate of 5°C / min with 5% oxygen-poor (nitrogen balanced) as the carrier gas. The sample mass change was recorded during the heating process, and finally the carbon deposition amount was calculated.

[0084] Example 1

[0085] 500g of CA-70 cement (main components are calcium aluminate, calcium dialuminate and magnesium aluminate spinel) was taken, 30g of cellulose was added, and then 1000g of water was added and stirred uniformly (the mass ratio of solid powder to water was 0.53, and the slurry viscosity was 6.2 Pa·s). The mixture was poured into a mold to form a honeycomb coal-shaped mold (Φ10×10mm). After standing at 15°C for 8 hours, the mold was demolded, and water was sprayed every 4 hours. After repeating for 7 days, the dried blank was naturally air-dried at room temperature. The dried blank was placed in a muffle furnace and calcined at 600°C in air atmosphere for 4 hours. After cooling to room temperature, the calcined blank was sieved using a 16 mesh standard sieve, and the honeycomb coal-shaped catalyst carrier was collected.

[0086] A certain amount of cerium nitrate was taken, water and ammonia were added to prepare a mixed solution with cerium ion and ammonium ion concentrations of 0.2 mol / L and 1.5 mol / L, respectively; 100 g of the mixed solution was weighed and heated to 25°C under stirring, 5 g of the catalyst carrier obtained in Example 1 was added thereto, and stirring was continued for 24 hours, after which the catalyst carrier was taken out and dried at 95°C for 18 hours; the dried catalyst carrier was placed in a muffle furnace and calcined at 500°C in an air atmosphere for 10 hours, and after cooling to room temperature, an intermediate catalyst was obtained.

[0087] A certain amount of nickel nitrate, cobalt nitrate, ruthenium chloride and yttrium nitrate was weighed, and water was added to prepare a multi-component mixed solution with a total metal ion concentration of 0.5 mol / L, wherein the molar ratio of nickel, cobalt, ruthenium and yttrium was 1:1:0.02:0.005; the multi-component mixed solution was added dropwise to the intermediate catalyst until obvious liquid accumulation appeared at the bottom, and then it was dried at 110°C for 12 hours; the dried catalyst was placed in a muffle furnace and calcined at 500°C in an air atmosphere for 6 hours, and after cooling to room temperature, Catalyst 1 was obtained.

[0088] Example 2

[0089] 500 g of CA-70 cement (main components are calcium aluminate, calcium dialuminate and magnesium aluminum spinel) was taken, 40 g of sodium dodecyl sulfate was added, and then 500 g of water was added and stirred uniformly (solid powder to water mass ratio was 1.08, and the slurry viscosity was 8.8 Pa·s), and then it was injected into a mold to form a honeycomb coal-shaped mold (Φ10×10 mm); after standing at 23°C for 5 hours, the mold was demolded, and water was sprayed every 6 hours, and after repeating for 5 days, it was naturally air-dried at room temperature; the dried blank was placed in a muffle furnace and calcined at 500°C in an air atmosphere for 6 hours, and after cooling to room temperature; the calcined blank was sieved using a 16-mesh standard sieve, and a honeycomb coal-shaped catalyst carrier was collected.

[0090] A certain amount of cerium nitrate was taken, water and ammonia were added to prepare a mixed solution with cerium ion and ammonium ion concentrations of 0.6 mol / L and 2.4 mol / L, respectively; 100 g of the mixed solution was weighed and heated to 45°C under stirring, 5 g of the catalyst carrier obtained in Example 1 was added thereto, and stirring was continued for 12 hours, after which the catalyst carrier was taken out and dried at 110°C for 12 hours; the dried catalyst carrier was placed in a muffle furnace and calcined at 600°C in an air atmosphere for 6 hours, and after cooling to room temperature, an intermediate catalyst was obtained.

[0091] Take an appropriate amount of nickel nitrate, cobalt nitrate, ruthenium chloride and yttrium nitrate, add water to prepare a multi-component mixed solution with a total metal ion concentration of 0.5 mol / L, wherein the molar ratio of nickel, cobalt, ruthenium, yttrium is 1:1:0.05:0.01; drop the multi-component mixed solution on the intermediate catalyst drop by drop until obvious liquid accumulation appears at the bottom, then dry it at 95℃ for 18 hours; place the dried catalyst in a muffle furnace, calcine it at 450℃ in air atmosphere for 10 hours, and cool it to room temperature after the end, which is catalyst 2.

[0092] Example 3

[0093] Take 500g CA-70 cement (main components are calcium aluminate, calcium dialuminate and magnesium aluminum spinel), mix in 30g triterpene saponin, then add 360g water and stir until uniform (solid powder to water mass ratio is 1.47, slurry viscosity is 18.5 Pa·s), pour into a honeycomb coal-shaped mold (Φ10×10mm); demold after standing at 30℃ for 3 hours, spray water every 8 hours, repeat for 3 days, then air dry at room temperature; place the dried blank in a muffle furnace, calcine it at 300℃ in air atmosphere for 10 hours, and cool it to room temperature after the end; screen the calcined blank using a 16 mesh standard sieve, and collect the honeycomb coal-shaped catalyst carrier.

[0094] Take an appropriate amount of cerium nitrate, add water and ammonia to prepare a mixed solution with a cerium ion and ammonium ion concentration of 1 mol / L and 3 mol / L respectively; take 100g of the above mixed solution and heat it to 60℃ under stirring, then add 5g of the catalyst carrier obtained in Example 1, continue stirring for 4 hours, then take out the catalyst carrier and dry it at 130℃ for 6 hours; place the dried catalyst carrier in a muffle furnace, calcine it at 650℃ in air atmosphere for 5 hours, and cool it to room temperature after the end, which is the intermediate catalyst.

[0095] Take an appropriate amount of nickel nitrate, cobalt nitrate, ruthenium chloride and yttrium nitrate, add water to prepare a multi-component mixed solution with a total metal ion concentration of 3 mol / L, wherein the molar ratio of nickel, cobalt, ruthenium, yttrium is 1:1:0.4:0.1; drop the multi-component mixed solution on the intermediate catalyst drop by drop until obvious liquid accumulation appears at the bottom, then dry it at 130℃ for 6 hours; place the dried catalyst in a muffle furnace, calcine it at 600℃ in air atmosphere for 2 hours, and cool it to room temperature after the end, which is catalyst 3.

[0096] Example 4

[0097] Take 500 g of CA-70 cement (main components are calcium aluminate, calcium dialuminate and magnesium aluminate spinel), mix in 30 g of cellulose, then add 1000 g of water and stir until uniform (solid powder to water mass ratio is 0.53, slurry viscosity is 6.2 Pa·s), pour into a mold to make a honeycomb coal-shaped mold (Φ10×10 mm); after standing at 15℃ for 8 hours, demold, spray water every 4 hours, repeat for 7 days, then air dry at room temperature; place the dried blank in a muffle furnace, calcine at 600℃ in air atmosphere for 4 hours, then cool to room temperature; screen the calcined blank using a 16 mesh standard sieve, collect the honeycomb coal-shaped catalyst carrier.

[0098] Take an appropriate amount of cerium nitrate, add water and ammonia to prepare a mixed solution with a cerium ion concentration of 0.2 mol / L and an ammonium ion concentration of 1.5 mol / L; weigh 100 g of the above mixed solution and heat to 25℃ under stirring, then add 5 g of the catalyst carrier obtained in Example 1, continue stirring for 24 hours, then take out the catalyst carrier and dry at 95℃ for 18 hours; place the dried catalyst carrier in a muffle furnace, calcine at 500℃ in air atmosphere for 10 hours, then cool to room temperature to obtain an intermediate catalyst.

[0099] Take appropriate amounts of nickel nitrate, cobalt nitrate and ruthenium chloride, add water to prepare a multi-component mixed solution with a total metal ion concentration of 0.5 mol / L, wherein the molar ratio of nickel, cobalt and ruthenium is 1:1:0.02; drop the multi-component mixed solution onto the intermediate catalyst drop by drop until a significant liquid accumulation appears at the bottom, then dry it at 110℃ for 12 hours; place the dried catalyst in a muffle furnace, calcine at 500℃ in air atmosphere for 6 hours, then cool to room temperature to obtain Catalyst 4.

[0100] Comparative Example 1

[0101] Take a certain commercial methane steam reforming catalyst (Southwest Institute Z111 series SMR catalyst) as Comparative Catalyst 1.

[0102] Comparative Example 2

[0103] Take appropriate amounts of nickel nitrate, cobalt nitrate, ruthenium chloride and yttrium nitrate, add water to prepare a multi-component mixed solution with a total metal ion concentration of 0.7 mol / L, wherein the molar ratio of nickel, cobalt, ruthenium and yttrium is 1:1:0.05:0.01; drop the multi-component mixed solution onto the catalyst carrier obtained in Example 1 drop by drop until a significant liquid accumulation appears at the bottom, then dry it at 110℃ for 12 hours; place the dried catalyst in a muffle furnace, calcine at 500℃ in air atmosphere for 6 hours, then cool to room temperature to obtain Comparative Catalyst 2.

[0104] Comparative Example 3

[0105] A certain amount of cerium nitrate is prepared into a mixed solution with the concentration of cerium ion and ammonium ion being 0.5 mol / L and 2.4 mol / L respectively; 100 g of the mixed solution is weighed and heated to 45℃ under stirring, 5 g of alpha phase alumina particles is added into the mixed solution, and the stirring is continued for 12 hours, then the catalyst carrier is taken out and dried at 110℃ for 12 hours; the dried catalyst carrier is placed in a muffle furnace and calcined at 600℃ in air atmosphere for 6 hours, and then cooled to room temperature to obtain an intermediate catalyst; a certain amount of nickel nitrate, cobalt nitrate, ruthenium chloride and yttrium nitrate is prepared into a multi-component mixed solution with the total concentration of metal ions being 0.7 mol / L, wherein the molar ratio of nickel, cobalt, ruthenium and yttrium is 1:1:0.05:0.01; the multi-component mixed solution is added dropwise on the intermediate catalyst until obvious liquid accumulation appears at the bottom, then the catalyst is dried at 110℃ for 12 hours; the dried catalyst is placed in a muffle furnace and calcined at 500℃ in air atmosphere for 6 hours, and then cooled to room temperature, which is the comparative catalyst 3.

[0106] Catalyst characterization analysis:

[0107] The catalysts 1-4 and the comparative catalysts 1-3 prepared in Examples 1-4 and Comparative Examples 1-3 are subjected to characterization analysis, and the results are shown in Table 1.

[0108] As shown in the data in Table 1, the element composition of the catalyst prepared in the application is very close to the feeding amount, the active components such as nickel, cobalt, ruthenium, yttrium and cerium are effectively controlled, and the preparation effect is consistent with the expectation.

[0109] The average BET specific surface area of the catalyst prepared in the application is 2.3 times of that of the comparative catalyst 1, which provides an ideal contact surface for the raw materials and the active sites of the catalyst, and is beneficial to the mass transfer process of the raw materials and the products, thereby improving the reaction performance.

[0110] The lateral pressure strength of the catalyst prepared in the application is about 663 N / cm, which is higher than that of the comparative catalysts 1 and 3, which reflects the high strength characteristics of the catalyst, and the catalyst is more likely to maintain stable morphology under high temperature and high pressure reaction conditions.

[0111] The porosity of the catalyst prepared in the application is higher than 12%, which is beneficial to the diffusion of the reactants and the products.

[0112] As shown in the data in Table 1, the element composition of the catalyst prepared in the application is very close to the feeding amount, the active components such as nickel, cobalt, ruthenium, yttrium and cerium are effectively controlled, and the preparation effect is consistent with the expectation. Figure 2 As shown in the data in Table 1, the element composition of the catalyst prepared in the application is very close to the feeding amount, the active components such as nickel, cobalt, ruthenium, yttrium and cerium are effectively controlled, and the preparation effect is consistent with the expectation. Figure 1 The microstructure of the catalyst 3 is consistent with that of the catalyst 1, and the average particle size is less than 50 nm.

[0113] As shown in the data in Table 1, the element composition of the catalyst prepared in the application is very close to the feeding amount, the active components such as nickel, cobalt, ruthenium, yttrium and cerium are effectively controlled, and the preparation effect is consistent with the expectation. Figure 3It can be known that the high anti-carbon-deposition methane reforming catalyst 3 prepared by the method of the application forms a target double-stage pore structure; the macropore with a pore diameter of 100 nm or more accounts for 98.05%, and the mesopore and micropore with a pore diameter of 0.5-50 nm accounts for 1.95%.

[0114] In conclusion, the high anti-carbon-deposition methane reforming catalyst can be successfully prepared by the method provided by the application.

[0115] Table 1 Characterization results of catalysts prepared in examples and comparative examples

[0116]

[0117] Catalyst reaction performance test:

[0118] The catalysts 1-3 and the comparative catalysts 1-3 prepared in Examples 1-3 and Comparative Examples 1-3 are tested for catalytic performance by using a fixed bed complete small test equipment. Before the test, the catalysts are activated and treated. The catalyst bed is first purged with nitrogen until the oxygen content at the outlet is less than 0.2%, and then the nitrogen purging is maintained, and the temperature is increased to 300℃ at a temperature increasing rate of 20℃ / hour. After the temperature is stable for 0.5 hours, hydrogen is introduced (the hydrogen content is increased by 2% each time), and then it is stable for 0.5 hours. The above steps are repeated, and the temperature is gradually increased to 700℃ and the hydrogen concentration is increased to 30% at a temperature increasing rate of 20℃ / hour, a temperature increasing step of 50℃ / time and a hydrogen content increasing step of 2% per time, and the temperature is maintained for 4 hours. After reduction, the hydrogen content is reduced to zero at a decreasing gradient of 10% per time, and the temperature is adjusted to the reaction temperature. The catalytic performance test results are shown in Table 2.

[0119] Table 2 Reaction performance test results of catalysts prepared in examples and comparative examples

[0120]

[0121]

[0122] It can be known from the data in Table 2 that under the conditions of methane steam reforming (H2O:CO2:CH4=2:0:1) and methane dry reforming (H2O:CO2:CH4=0:1:1), the catalysts prepared by the application all have the highest methane conversion rate, the optimal performance stability and the lowest reaction carbon deposition amount, and thus have the best performance.

[0123] In addition to the above activation condition (activation condition 1), the catalyst 2 is activated by using different activation conditions, wherein:

[0124] Activation condition 2: first purging the catalyst bed with nitrogen until the oxygen content at the outlet is less than 0.2%, then keeping the nitrogen purging and increasing the temperature to 200°C at a rate of 20°C / hour, after the temperature is stable for 0.2 hours, hydrogen is introduced (the hydrogen content is increased by 5% each time), and then stable for 1 hour; repeating the above steps, gradually increasing the temperature to 600°C and the hydrogen concentration to 100% at a rate of 50°C / hour, a temperature increasing step of 80°C each time, and a hydrogen content increasing step of 5% each time, and keeping for 2 hours; after the reduction is completed, the hydrogen content is reduced to zero at a decreasing gradient of 20% each time, and the temperature is adjusted to the reaction temperature.

[0125] Activation condition 3: first purging the catalyst bed with nitrogen until the oxygen content at the outlet is less than 0.2%, then keeping the nitrogen purging and increasing the temperature to 350°C at a rate of 50°C / hour, after the temperature is stable for 2 hours, hydrogen is introduced (the hydrogen content is increased by 2% each time), and then stable for 0.2 hours; repeating the above steps, gradually increasing the temperature to 800°C and the hydrogen concentration to 30% at a rate of 5°C / hour, a temperature increasing step of 20°C each time, and a hydrogen content increasing step of 2% each time, and keeping for 4 hours; after the reduction is completed, the hydrogen content is reduced to zero at a decreasing gradient of 5% each time, and the temperature is adjusted to the reaction temperature.

[0126] The results of the catalytic performance test are shown in Table 3.

[0127] Table 3: results of the catalyst 2 reaction performance test under different activation conditions

[0128]

[0129] From the data in Table 3 above, it can be seen that the different activation conditions proposed in the present application can all achieve ideal catalyst activation effects, and the performance is better than that of the comparative catalyst.

[0130] It is easily understood that the above examples are only examples for clearly illustrating the present application, and do not mean that the present application is limited to this. Other different forms of changes or variations can be made on the basis of the above description by those of ordinary skill in the art. Here, it is not necessary and impossible to exhaust all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A highly coking resistant methane reforming catalyst, said catalyst comprising an active phase, an auxiliary phase and a support phase; wherein, The active phase is a nickel-cobalt-ruthenium alloy or a nickel-cobalt-ruthenium-yttrium alloy, the auxiliary phase is cerium oxide rich in oxygen vacancies, and the support phase is a composite calcium magnesium aluminate.

2. The catalyst according to claim 1, characterized in that, The catalyst comprises, by weight percentage, the following components in the form of elements contained herein: nickel 4-6%, cobalt 4-6%, ruthenium 0.1-3%, yttrium 0-0.1%, cerium 4-10%, calcium 8-15%, magnesium 0.1-5%, aluminum 25-35%, oxygen 30-45%, with a total mass based on the elemental form contained in the catalyst being 100%.

3. The catalyst according to claim 1 or 2, characterized in that, The active phase nickel-cobalt-ruthenium alloy or nickel-cobalt-ruthenium-yttrium alloy is an alloy nanoparticle with an average particle size of ≤ 50 nm; and / or, in the auxiliary phase cerium oxide rich in oxygen vacancies, the average valence of cerium is between +1.5 and +3; and / or, the carrier phase composite calcium-magnesium-aluminate has a porous structure with a specific surface area of not less than 20 m 2 / g, and a strength of not less than 300 N / particle.

4. The catalyst according to any one of claims 1-3, characterized in that, The inner and outer surfaces of the support phase are loaded with a volcano-shaped active phase and an auxiliary phase; it has a bilevel pore structure with a porosity of not less than 12%, of which macropores with a pore size of 100 nm or more account for not less than 98%, and micropores with a pore size of 0.5–50 nm account for 0.1–2%.

5. A method for preparing a high-resistance methane reforming catalyst according to any one of claims 1-4, comprising the following steps: Step 1: Mix solid powder containing calcium aluminate (preferably calcium aluminate, dicalcium aluminate), magnesium aluminum spinel and additives with water to form a slurry, pour it into a mold to form a blank of the target shape, and spray water to moisten it multiple times. Step 2: Dry and calcine the billet, cool it to room temperature, sieve to remove fine powder, and collect the granular catalyst carrier; Step 3: Mix cerium salt and ammonia water thoroughly to prepare a mixed solution; Step 4: Place the catalyst support into the mixed solution from Step 3, stir, dry, and calcine to obtain the intermediate catalyst; Step 5: Mix the nickel salt, cobalt salt, ruthenium salt and optional yttrium salt with water to prepare a multi-component mixed solution; Step 6: Add the multi-component mixed solution to the intermediate catalyst until the saturation water absorption is reached, then dry and calcine to obtain the catalyst.

6. The preparation method according to claim 5, characterized in that, In step 1, the mass ratio of solid powder to water is 0.3 to 1.5, and the slurry viscosity is 5 to 20 Pa·s; and / or, the additives include, but are not limited to, one or more of cellulose, polyvinyl alcohol, sodium dodecyl sulfate, rosin thermal polymer, and triterpenoid saponins, with an addition amount not exceeding 10 wt%, based on the total mass of calcium aluminate and magnesium aluminum spinel solid powders.

7. The preparation method according to claim 5 or 6, characterized in that, The formed blank in step 1 needs to be left to stand for a period of time. The preferred standing temperature is 5-30℃, and more preferably 15-25℃. The standing time is 3-8 hours, and more preferably 4-6 hours.

8. The preparation method according to any one of claims 5-7, characterized in that, In step 4, the solid-liquid ratio of the catalyst support to the mixed solution is 1:10 to 1:50, and / or the stirring temperature is 15 to 80°C and the stirring time is 4 to 24 hours; and / or, in step 4, the drying temperature is 95 to 130°C and the drying time is 6 to 18 hours, the calcination temperature is 500 to 700°C and the calcination time is 4 to 10 hours, and the calcination atmosphere is air or an inert atmosphere.

9. The preparation method according to any one of claims 5-8, characterized in that, The total concentration of metal ions in the multi-component mixed solution described in step 5 is 0.5–3 mol / L; and / or, the calcination temperature in step 6 is 300–600°C, the calcination time is 2–10 hours, and the calcination atmosphere is air or an inert atmosphere.

10. The use of the high-coking-resistant methane reforming catalyst according to any one of claims 1-4 or the catalyst prepared by any one of claims 5-9 as a catalyst for methane steam reforming, methane carbon dioxide reforming, methane autothermal reforming, methane partial oxidative reforming, and any combination thereof.

11. The use according to claim 10, characterized in that, The catalyst must undergo activation treatment before use. The activation treatment includes the following steps: Step 1: Purge the catalyst bed with inert gas until the outlet oxygen content meets the standard, preferably the outlet oxygen volume content is not higher than 0.2%; Step 2: Slowly increase the temperature to the activation initiation temperature, gradually increasing the reducing gas content and temperature to the target value in several stages, and then maintain the temperature. Step 3: After step 2, reduce the reducing gas content to zero with a fixed concentration gradient, maintain inert gas purging, and adjust the catalyst bed temperature to the reaction temperature.

12. The use according to claim 11, characterized in that, In step 2, the activation start temperature is 200–350°C; the reducing gas is hydrogen, and the increase in reducing gas content is no more than 5% per cycle; and / or, the temperature rise rate is set to 5–50°C / hour, the increase in catalyst bed temperature is no more than 80°C per cycle, the activation endpoint is 550–850°C, and the target reducing gas content is 20–100%.

13. The use according to claim 11 or 12, characterized in that, In step 3, the reduction gradient of the reducing gas content is 5-20%; the temperature change rate is set not to exceed 50℃ / hour.

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