Methane reforming reaction catalyst as well as preparation method and application thereof

Abstract

The invention provides a methane reforming reaction catalyst and a preparation method and application thereof.The catalyst is composed of a Ni-Ga alloy first functional component, an oxygen-vacancy-rich RuOx nano-particle second functional component and a high-alumina cement forming agent which serve as a methane reforming reaction active component, a carbon removal reaction active component and a structural additive respectively, and the Ni-Ga alloy first functional component, the oxygen-vacancy-rich RuOx nano-particle second functional component and the high-alumina cement forming agent serve as a high-alumina cement forming agent; the preparation method comprises the steps of precursor preparation, mixing and grinding, molding and drying, high-temperature secondary phase inversion heat treatment and the like. According to the invention, a multi-element complex-phase catalytic system is constructed, so that reaction carbon deposit is effectively reduced; the strength of the catalyst is obviously improved, so that the catalyst can keep an ideal form for a long time in a high-temperature and high-pressure environment; a high-temperature secondary phase transfer heat treatment method and process are provided, and the stability of a catalytic system is improved. The scheme is simple and easy to implement, the catalyst does not need to be reduced again before use, the field equipment requirement and the manual operation difficulty are reduced, and application and popularization in the field of methane reforming are facilitated.

Description

Technical Field

[0001] The present invention relates to the field of industrial catalysis, and particularly relates to a catalyst for methane reforming reaction, a preparation method thereof, and an application thereof. Background Art

[0002] The methane reforming reaction is the cornerstone of the methane-to-hydrogen / syngas process and plays an important role in the future clean utilization of fossil energy and the resource utilization of carbon dioxide.

[0003] For a long time, the carbon deposition problem has been the bottleneck of the methane reforming reaction. The reason is that under the methane reforming conditions, side reactions such as methane cracking and carbon monoxide disproportionation are prone to occur, resulting in a large amount of carbon deposition. This not only greatly reduces the catalytic performance but also causes the catalyst to break, ultimately resulting in the blockage of the catalyst bed and the shutdown of the device. To alleviate the carbon deposition problem, the industrial methane steam reforming process mainly adopts the method of increasing the feed water-carbon ratio. However, about 70% of the steam idles in the system and cannot be converted into syngas products in this way, making the operating energy consumption remain high. And once the water-carbon ratio is reduced or carbon dioxide is introduced to replace steam, carbon deposition is still likely to occur, which is also the main reason why the current methane carbon dioxide reforming process and methane combined reforming process are difficult to be industrially applied.

[0004] To solve this problem, researchers generally adopt optimization strategies such as improving the stability of the reforming catalyst, introducing carbon scavengers, and enhancing the strength of the catalyst. The invention patent CN202111085730.2 discloses an anti-carbon deposition nickel-based catalyst, a preparation method thereof, and an application thereof, which is composed of the active component metal Ni, the promoter Ga or B, and the metal oxide component CeO 2 The doping of Ga or B effectively inhibits the sintering of nickel particles and improves the catalytic stability of the catalyst. The invention patent CN202210333577.9 discloses a catalyst for reforming natural gas to produce hydrogen, a preparation method thereof, and an application thereof, which is composed of a platinum-loaded catalyst with an aluminum-manganese composite oxide and a palladium-loaded catalyst with cerium oxide, alleviating the problems of easy carbon deposition and easy agglomeration and sintering of the catalyst. However, none of the above patents involve the optimization of the mechanical strength of the catalyst, and it needs to be formed before it can be used in industrial production, and the forming effect is unknown.

[0005] The invention patent CN201710124445.4 discloses a high-strength multi-porous catalyst for methane tri-reforming reaction and a preparation method thereof. First, a molded carrier is prepared by die pressing and calcination, and then it is impregnated in a metal salt solution to obtain a high-strength catalyst. The invention patent CN201910778125.X discloses a dry gas to hydrogen conversion catalyst and a preparation method thereof. The catalyst finished product is prepared by adding water to form, autoclaving and drying the active components, pure calcium aluminate cement and lubricant, further balancing the loss of alkali metals, the anti-carbon deposition effect and the utilization of active components. The above patents aim to improve the strength of the catalyst. However, the mature catalyst formula and preparation method are directly adopted, and the improvement effect on the catalytic performance is not obvious.

[0006] Therefore, although researchers have made some stage progress in the development field of methane reforming catalysts in recent years, there is still a large room for optimization in reasonably constructing the "reforming catalyst - anti-carbon agent - forming agent" catalytic system and strengthening the interaction between components. Summary of the Invention

[0007] In view of the above problems existing in the prior art, the present invention provides a methane reforming reaction catalyst and a preparation method thereof, which can be used for methane steam reforming and dry reforming reactions, and has the advantages of anti-carbon deposition, high strength, stable performance, etc.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] In the first aspect, the present invention provides a methane reforming reaction catalyst, which is a multi-component composite catalyst composed of a first functional component, a second functional component and a forming agent;

[0010] The first functional component is a Ni-Ga alloy,

[0011] The second functional component is RuOx nanoparticles,

[0012] The forming agent is high-alumina cement.

[0013] In the present invention, for the catalyst, in the form of oxides of the metal elements contained therein, it includes the following components in mass percentage: NiO 15 - 20%, such as 15, 16, 17, 18, 19, 20%,

[0014] Ga 2 O 3 5 - 10%, such as 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10%,

[0015] RuO 20.1 to 1%, such as 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1%,

[0016] Al 2 O 3 30 to 40%, such as 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40%,

[0017] CaO 30 to 40%, such as 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40%,

[0018] Based on the total mass of the metal element oxides contained in the catalyst being 100%.

[0019] In the present invention, for the first functional component, the Ni-Ga alloy, the molar ratio of Ni:Ga is between 1.6:1 and 6:1, such as 1.6:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1.

[0020] In the present invention, for the second functional component, the RuO x nanoparticles are oxygen-rich vacancy RuO x nanoparticles, where x ranges from 0.5 to 2, such as 0.5, 0.8, 1, 1.3, 1.5, 1.8, 2.

[0021] In the present invention, for the shaping agent, the high-alumina cement, where the content of Al 2 O 3 is not less than 45 wt%, such as 45, 50, 55, 60, 65, 70 wt%, etc.; the high-alumina cement also contains not more than 50 wt%, such as 50, 45, 40, 35 wt%, etc. of calcium oxide (CaO).

[0022] The catalyst of the present invention provides active sites for the methane reforming reaction through the first functional component, converting methane, steam and carbon dioxide into carbon monoxide and hydrogen; provides active sites for the carbon elimination reaction through the second functional component, promoting the decomposition reaction of coke deposition, especially reducing the excessive growth of filamentous carbon inside the catalyst; the shaping agent can, on the one hand, improve the overall strength of the catalyst, and on the other hand, provide α-Al 2 O 3 auxiliaries through high-temperature phase transformation, thereby improving the activity and stability of the catalytic system.

[0023] Second, the present invention provides a preparation method of the above methane reforming reaction catalyst, wherein the preparation of the catalyst precursor includes the following steps:

[0024] S1: Add excess urea to the mixed salt solution of Ni, Ga and Ru and mix them evenly, then perform high-temperature hydrothermal reaction in a high-pressure reactor. After the reaction, recover the precipitate and dry it to obtain Ni-Ga precursor and RuO x a mixture of nanoparticle precursors;

[0025] S2: uniformly mixing the precursor mixture obtained in step S1 with high alumina cement, and grinding them sufficiently;

[0026] S3: Add an appropriate amount of pure water to the ground mixture obtained in step S2 and knead it until it is soft, then extrude it into shape, cut it, and dry it to obtain a catalyst precursor.

[0027] In the present invention, the amount of urea in step S1 is excessive relative to the mixed salt of Ni, Ga and Ru, and the molar ratio of urea: (Ni+Ga+Ru) is 1.2:1 to 1.5:1;.

[0028] In the present invention, the Ni, Ga, Ru mixed salt solution in step S1 is an aqueous solution of Ni, Ga, Ru mixed salt; preferably, the total concentration of Ni, Ga, Ru in the aqueous solution is 0.1 to 5 mol / L, for example, 0.1, 0.5, 1, 2, 3, 4, 5 mol / L;

[0029] Preferably, in the Ni, Ga, Ru mixed salt solution, the molar ratio of Ni, Ga, Ru is 1-5:1:0.1-0.5, for example (1, 2, 3, 4, 5):1:(0.1, 0.2, 0.3, 0.4, 0.5), preferably 1.6-3:1:0.15-0.45;

[0030] Preferably, the Ni, Ga, Ru mixed salt comprises at least one salt selected from nitrates, chlorides, and the like.

[0031] In the present invention, the high temperature hydrothermal reaction in step S1 has a reaction temperature of 160 to 190° C., for example, 160, 170, 180, 190° C., and a reaction time of 18 to 48 hours, for example, 18, 20, 25, 30, 35, 40, 45, 48 hours;

[0032] The high temperature hydrothermal reaction has a reaction pressure of 0.8 to 5 MPa, such as 0.8, 1, 2, 3, 4, or 5 MPa.

[0033] In the present invention, the mass ratio of the precursor mixture and the high alumina cement in step S2 is 1:1.5 to 1:4, for example, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4.

[0034] In the present invention, the grinding in step S2 is a conventional processing method in the art, and the methods include but are not limited to any one of ball milling, column milling, rod milling, tube milling, autogenous milling, vertical milling, etc.

[0035] The powder obtained after grinding has an average particle size not greater than 200 μm, such as 190, 170, 150, 120, 100, 80, 60, 40, 20, 5 μm.

[0036] In the present invention, the shapes of the catalyst precursor extrusion molding in step S3 include but are not limited to any one of bar shape, cylindrical shape, single-hole cylindrical shape, multi-hole cylindrical shape, circular ring shape, wheel shape, etc.

[0037] In some preferred embodiments, the method for preparing the methane reforming reaction catalyst of the present invention further includes performing high-temperature secondary phase transition heat treatment on the catalyst precursor to obtain a catalyst product.

[0038] In some specific implementation manners, the high-temperature secondary phase transition heat treatment is composed of four consecutive heat treatment stages, namely a dehydration stage, an alloy phase transition stage, an Al 2 O 3 phase transition stage, and a cooling stage.

[0039] In the present invention, for the dehydration stage of the high-temperature secondary phase transition heat treatment, the temperature is 120 - 150 °C, such as 120, 130, 140, 150 °C, the pressure is slightly positive pressure, the atmosphere is an inert atmosphere, and the treatment time is 6 - 8 h, such as 6, 6.5, 7, 7.5, 8 h.

[0040] In the present invention, for the alloy phase transition stage of the high-temperature secondary phase transition heat treatment, the temperature is 700 - 800 °C, such as 700, 720, 740, 760, 780, 800 °C, the pressure is slightly positive pressure, the atmosphere is a reducing atmosphere, and the treatment time is 4 - 6 h, such as 4, 4.5, 5, 5.5, 6 h.

[0041] In the present invention, for the Al 2 O 3 phase transition stage of the high-temperature secondary phase transition heat treatment, the temperature is 850 - 1000 °C, such as 850, 880, 900, 930, 950, 980, 1000 °C, the pressure is slightly positive pressure, the atmosphere is an inert atmosphere, and the treatment time is 4 - 6 h, such as 4, 4.5, 5, 5.5, 6 h.

[0042] In the present invention, the four stages of the high-temperature secondary phase transition heat treatment are carried out continuously in sequence, and the heating rate must be strictly controlled not to be higher than 8 °C / min, such as 8, 7, 6, 5, 4, 3, 2, 1 °C / min.

[0043] In the present invention, in the cooling stage of the high-temperature secondary phase transition heat treatment, the cooling rate is not higher than 10 °C / min, such as 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 °C / min, the pressure is slightly positive pressure, the atmosphere is an inert atmosphere, and the furnace can be taken out only when the temperature drops below 150 °C.

[0044] In the present invention, the inert atmosphere used in the dehydration stage, the Al 2 O 3 phase transition stage, and the cooling stage is selected from at least one of helium, nitrogen, and argon;

[0045] The reducing atmosphere used in the alloy phase transition stage is selected from any one of hydrogen and carbon monoxide, or any one of the mixed gases of the two with an inert gas, such as hydrogen, hydrogen / helium mixture, hydrogen / nitrogen mixture, hydrogen / argon mixture, carbon monoxide, carbon monoxide / helium mixture, carbon monoxide / nitrogen mixture, carbon monoxide / argon mixture, etc.; the above-mentioned inert atmosphere or reducing atmosphere is a conventional selection in the field, and in actual operation, those skilled in the art can select it by themselves.

[0046] The slightly positive pressure in the four stages of the high-temperature secondary phase transition heat treatment is usually 0.2-2.0 MPa, such as 0.2, 0.5, 1, 1.5, 2 MPa.

[0047] In the preparation method of the catalyst of the present invention, in the dehydration stage of the high-temperature secondary phase transition heat treatment of the precursor, it is used to remove the free water in the catalyst precursor, make the precursor fully dry, and avoid the fragmentation of the catalyst during the heating process; the alloy phase transition stage is used to convert the Ni-Ga precursor into a Ni-Ga alloy, and at the same time form RuO with rich oxygen vacancies x nanoparticles; Al 2 O 3 The phase transition stage is used to convert γ-Al 2 O 3 into θ-Al 2 O 3 / δ-Al 2 O 3 and further convert it into α-Al 2 O 3 ; the cooling stage is used to control the cooling process and protect the first functional component and the second functional component from being oxidized by oxygen in the air.

[0048] In the third aspect, the present invention also provides the application of the methane reforming reaction catalyst described above in the steam reforming and dry reforming reactions of methane.

[0049] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0050] The present invention provides a methane reforming reaction catalyst and a preparation method thereof, constructs a multi-phase catalytic system comprising reforming active sites, carbon elimination active sites and additives, and effectively reduces reaction carbon deposition; uses high-alumina cement as a forming agent, significantly improves the strength of the catalyst, and enables it to maintain an ideal shape under high temperature and high pressure environments.

[0051] The present invention further proposes a high-temperature secondary phase transformation heat treatment method and process, and simultaneously in-situ forms α-Al x while obtaining Ni-Ga alloy and RuO nanoparticle-rich oxygen vacancies 2 O 3 , which improves the stability of the catalytic system as an additive.

[0052] The preparation method proposed by the present invention is simple and easy to implement, and there is no need to re-reduce the catalyst before use, which reduces the requirements for on-site equipment and the difficulty of manual operation, and is conducive to the popularization and application in the fields of methane steam reforming, methane dry reforming, etc.

[0053] It should be understood that the content described in the summary of the invention is not intended to limit the key or important features of the following embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description.

[0054] Unless otherwise specified, the pressures described in the present invention are absolute pressures. Detailed Description of the Invention

[0055] In order to enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the following will clearly and completely describe the technical solutions in one or more embodiments of this specification in conjunction with one or more embodiments of this specification. Obviously, the described embodiments are only a part of the embodiments of this specification, rather than all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this document.

[0056] It should be noted that the description of the embodiments of the present invention is only for more clearly explaining the technical solutions of the embodiments of the present invention, and does not constitute a limitation on the technical solutions provided by the embodiments of the present invention.

[0057] The sources of the main raw materials in the embodiments and comparative examples of the present invention are as follows. Others are obtained from ordinary commercial channels if not otherwise specified:

[0058] Nickel nitrate: Sinopharm Chemical Reagent Co., Ltd., purity 99%;

[0059] Gallium nitrate salt: Sinopharm Chemical Reagent Co., Ltd., purity 99%;

[0060] Ruthenium nitrate: Sinopharm Chemical Reagent Co., Ltd., purity 99%;

[0061] Urea: Sinopharm Chemical Reagent Co., Ltd., purity 99%;

[0062] High alumina cement: Zhengzhou Jianai, Al 2 O 3 content 48 wt%, CaO content 50 wt%.

[0063] Example 1:

[0064] Prepare the catalyst precursor, the steps are as follows:

[0065] Prepare a mixed salt solution with a total concentration of 2 mol / L and a volume of 100 mL by mixing nickel nitrate, gallium nitrate and ruthenium nitrate according to the molar ratio of Ni:Ga:Ru = 5:1:0.1. Then add 0.25 mol of urea to the solution, stir well until the solution is clear, and transfer it to a high-pressure reactor. Carry out hydrothermal reaction at 160 °C for 48 h (pressure 2.2 MPa); After the reaction, take out the product, filter and recover the filter cake, and dry it at 120 °C for 12 h;

[0066] Take 10 g of the dried powder above, add 15 g of high alumina cement and mix evenly. Place it in a ball mill and ball mill for 30 min until the average particle size is 20 μm;

[0067] Take out the ball-milled powder, add an appropriate amount of water, and use an extrusion machine to form it into a strip shape, and dry it naturally for 24 h to obtain catalyst precursor 1.

[0068] Example 2:

[0069] Prepare the catalyst precursor, the steps are as follows:

[0070] Prepare a mixed salt solution with a total concentration of 1 mol / L and a volume of 1 L by mixing nickel nitrate, gallium nitrate and ruthenium nitrate according to the molar ratio of Ni:Ga:Ru = 1.6:1:0.2. Then add 1.2 mol of urea to the solution, stir well until the solution is clear, and transfer it to a high-pressure reactor. Carry out hydrothermal reaction at 180 °C for 24 h (pressure 0.8 MPa); After the reaction, take out the product, filter and recover the filter cake, and dry it at 120 °C for 12 h;

[0071] Take 20 g of the dried powder above, add 45 g of high alumina cement and mix evenly. Place it in a ball mill and ball mill for 1.5 h until the average particle size is 15 μm;

[0072] Take out the ball-milled powder, add an appropriate amount of water, and use an extrusion machine to form it into a single-hole cylindrical shape, and dry it naturally for 30 h to obtain catalyst precursor 2.

[0073] Example 3:

[0074] Prepare the catalyst precursor, the steps are as follows:

[0075] Prepare a mixed salt solution with a total concentration of 1 mol / L and a volume of 1 L by mixing nickel nitrate, gallium nitrate and ruthenium nitrate in a molar ratio of Ni:Ga:Ru = 3:1:0.5. Then add 1.5 mol of urea to the solution, stir well until the solution becomes clear, and transfer it to a high-pressure reactor. Carry out hydrothermal reaction at 190 °C for 18 h (pressure 1.6 MPa); after the reaction, take out the product, filter and recover the filter cake, and dry it at 120 °C for 12 h;

[0076] Take 20 g of the dried powder above, add 60 g of high-alumina cement and mix evenly. Place it in a ball mill and ball mill for 2 h until the average particle size is 12 μm;

[0077] Take out the ball-milled powder, add an appropriate amount of water, and use an extruder to form it into a porous cylinder. Dry it naturally for 30 h to obtain catalyst precursor 3.

[0078] Example 4:

[0079] Prepare a methane reforming reaction catalyst by subjecting the catalyst precursor to high-temperature secondary phase transition heat treatment. The steps are as follows:

[0080] Take 20 g of catalyst precursor 1, place it in a high-temperature muffle furnace with a controllable atmosphere, heat it to 120 °C at a heating rate of 8 °C / min under a nitrogen atmosphere of 0.2 MPa, and keep it warm for 6 h; then, heat it to 700 °C at a heating rate of 5 °C / min under a nitrogen atmosphere of 0.2 MPa and 5% hydrogen (balanced with nitrogen), and keep it warm for 4 h; then, heat it to 900 °C at a heating rate of 5 °C / min under a nitrogen atmosphere of 0.2 MPa, and keep it warm for 4 h; finally, cool it to 120 °C at a cooling rate of 10 °C / min under a nitrogen atmosphere of 0.2 MPa to complete the high-temperature secondary phase transition heat treatment and obtain catalyst 1.

[0081] In terms of the oxides of the metal elements contained therein, the mass percentage contents of each component of catalyst 1 are 19.4% of NiO, Ga 2 O 3 8.8%, RuO 2 0.4%, Al 2 O 3 35.2%, CaO 36.2%; among them, the molar ratio of Ni:Ga is 2.8:1.

[0082] Example 5:

[0083] Prepare a methane reforming reaction catalyst by subjecting the catalyst precursor to high-temperature secondary phase transition heat treatment. The steps are as follows:

[0084] Take 50 g of catalyst precursor 2 and place it in a high-temperature muffle furnace with a controllable atmosphere. Heat it to 120 °C at a heating rate of 5 °C / min under a nitrogen atmosphere of 0.25 MPa and hold for 8 h. Subsequently, heat it to 750 °C at a heating rate of 5 °C / min under a nitrogen atmosphere of 0.25 MPa with 10% hydrogen (balanced with nitrogen) and hold for 4 h. Then, heat it to 900 °C at a heating rate of 5 °C / min under a nitrogen atmosphere of 0.25 MPa and hold for 6 h. Finally, cool it to 120 °C at a cooling rate of 5 °C / min under a nitrogen atmosphere of 0.25 MPa to complete the high-temperature secondary phase transformation heat treatment and obtain catalyst 2.

[0085] In terms of the oxides of the metal elements contained in catalyst 2, the content of each component is 16.2% NiO, Ga 2 O 3 9.6%, RuO 2 0.9%, Al 2 O 3 36.3%, CaO 37.0%; the molar ratio of Ni:Ga is 2.1:1.

[0086] Example 6:

[0087] Preparation of a methane reforming reaction catalyst by high-temperature secondary phase transformation heat treatment of a catalyst precursor, the steps are as follows:

[0088] Take 50 g of catalyst precursor 3 and place it in a high-temperature muffle furnace with a controllable atmosphere. Heat it to 120 °C at a heating rate of 5 °C / min under a nitrogen atmosphere of 0.25 MPa and hold for 8 h. Subsequently, heat it to 800 °C at a heating rate of 5 °C / min under a nitrogen atmosphere of 0.25 MPa with 10% hydrogen (balanced with nitrogen) and hold for 6 h. Then, heat it to 1000 °C at a heating rate of 5 °C / min under a nitrogen atmosphere of 0.25 MPa and hold for 4 h. Finally, cool it to 120 °C at a cooling rate of 5 °C / min under a nitrogen atmosphere of 0.25 MPa to complete the high-temperature secondary phase transformation heat treatment and obtain catalyst 3.

[0089] In terms of the oxides of the metal elements contained in catalyst 3, the content of each component is 17.9% NiO, Ga 2 O 3 9.9%, RuO 2 0.7%, Al 2 O 3 35.9%, CaO 35.6%; the molar ratio of Ni:Ga is 2.3:1.

[0090] Comparative Example 1:

[0091] Prepare the most representative Ni / Al in the field of methane reforming by the impregnation method2 O 3 Catalyst: Prepare a nickel nitrate solution with a total concentration of 1 mol / L in 500 mL. Weigh an appropriate amount of commercial spherical α-Al 2 O 3 and put it into the solution, then stir for 12 h; take out the impregnated spherical α-Al 2 O 3 , dry it at 120 °C for 12 h to obtain Comparative Catalyst 1.

[0092] Comparative Example 2:

[0093] Take a certain commercial methane steam reforming catalyst (Southwest Research Institute Z111 series SMR catalyst) as Comparative Catalyst 2.

[0094] Comparative Example 3:

[0095] Referring to the preparation method of Catalyst 1, the difference is only that: in the preparation process of the precursor, no Ni salt is added, and other operations and conditions remain unchanged, to obtain Comparative Catalyst 3. Calculated in the form of oxides of the metal elements contained therein, the mass percentage of each component is Ga 2 O 3 11.2%, RuO 2 0.6%, Al 2 O 3 43.8%, CaO 44.4%.

[0096] Comparative Example 4:

[0097] Referring to the preparation method of Catalyst 1, the difference is only that: in the preparation process of the precursor, no Ga salt is added, and other operations and conditions remain unchanged, to obtain Comparative Catalyst 4. Calculated in the form of oxides of the metal elements contained therein, the mass percentage of each component is NiO 21.9%, RuO 2 2.1%, Al 2 O 3 37.6%, CaO 38.4%.

[0098] Comparative Example 5:

[0099] Referring to the preparation method of Catalyst 1, the difference is only that: in the preparation process of the precursor, no Ru salt is added, and other operations and conditions remain unchanged, to obtain Comparative Catalyst 5. Calculated in the form of oxides of the metal elements contained therein, the mass percentage of each component is NiO 20.1%, Ga 2 O 3 8.6%, Al 2 O 3 35.4%, CaO 35.9%.

[0100] Comparative Example 6:

[0101] Referring to the preparation method of Catalyst 1, the only difference is that in the process of preparing the precursor, the forming agent high-alumina cement is replaced by pseudo-boehmite, and other operations and conditions remain unchanged, and Comparative Catalyst 6 is prepared. Calculated in the form of the oxides of the metal elements contained therein, the mass percentage content of each component is 18.8% of NiO, Ga 2 O 3 8.1%, RuO 2 0.2%, Al 2 O 3 72.9%.

[0102] Catalyst characterization and analysis:

[0103] The catalysts 1-3 prepared in Examples 4-6 and Comparative Catalysts 1-6 prepared in Comparative Examples 1-6 were characterized and analyzed, and the results are shown in Table 1.

[0104] The performance test parameters adopted in each example of the present invention were all tested by conventional standard methods:

[0105] Ni content: Tested by inductively coupled plasma spectroscopy (ICP);

[0106] Specific surface area: Low-temperature nitrogen adsorption and desorption isotherm (calculated using the BET model);

[0107] Crystal phase: X-ray diffraction (XRD);

[0108] Crushing strength: Digital display particle strength tester.

[0109] Table 1 Characterization results of catalysts prepared in examples and comparative examples

[0110]

[0111] It can be seen from the data in Table 1 above that: the average Ni content of the catalysts prepared in the present invention is about 14%, the loss of metallic Ni during the preparation process is extremely low, and the preparation effect is consistent with the expectation.

[0112] The BET specific surface area of the catalysts prepared in the present invention is 1.9 times and 3.1 times that of Comparative Catalysts 1 and 2 on average, providing an ideal contact area for the raw materials and the catalysts; the average pore diameter is significantly higher than that of Comparative Catalyst 1 and Comparative Catalyst 2, so it is beneficial to the mass transfer process; the pore volume is higher than that of Comparative Catalysts 1 and 2, and has a higher tolerance to carbon deposition.

[0113] The catalysts prepared in the present invention contain Ni-Ga alloy, RuO 2 、α-Al 2 O 3The crystal structures of [substance] and CaO exhibit a multi-component composite crystal phase, while the crystal structures of Comparative Catalysts 1 and 2 are relatively simple. The technical solution of the present invention has obvious advantages.

[0114] The average strength of the catalyst prepared in the present invention is about 410 N / cm, which is higher than that of Comparative Catalysts 1, 2, and 6, reflecting its high-strength characteristics and being more likely to maintain morphological stability under high-temperature and high-pressure reaction conditions.

[0115] From Comparative Examples 3, 4, and 5, it can be seen that removing any one of the components Ni, Ga, and Ru cannot form the catalyst product described in the present invention.

[0116] Catalyst reaction performance test:

[0117] The catalytic reaction performances of the catalysts 1-3 prepared in Examples 4-6 and Comparative Catalysts 1-6 prepared in Comparative Examples 1-6 were respectively tested using a high-pressure fixed-bed reactor. The test reaction was the reforming of methane to syngas, and the reactants were methane, steam, and / or carbon dioxide. The reaction temperature was 800 °C, the pressure was 0.1 MPa, and the space velocity was 12000 h -1 , and the results are shown in Table 2. In Table 2, X CH4 (10 h) / % represents the methane conversion rate.

[0118] Table 2 Test results of the reaction performances of the catalysts prepared in the examples and comparative examples

[0119]

[0120]

[0121] From the data in Table 2 above, it can be seen that: whether it is in methane steam reforming (H 2 O:CO 2 :CH 4 = 3:0:1), methane dry reforming (H 2 O:CO 2 :CH 4 = 0:1:1) or methane combined reforming (H 2 O:CO 2 :CH 4 = 1:1:1) conditions, the catalysts prepared in the present invention all exhibit the highest methane conversion rate, the best performance stability, and the lowest reaction carbon deposition amount, so the reaction performance is the best.

Claims

1. A methane reforming reaction catalyst, characterized in that, it is a multi-phase composite catalyst composed of a first functional component, a second functional component and a forming agent; the first functional component is a Ni-Ga alloy, the second functional component is RuOx nanoparticles, and the forming agent is high alumina cement.

2. The methane reforming reaction catalyst according to claim 1, characterized in that, The catalyst, calculated in the form of oxides of the metal elements contained therein, comprises the following components in mass percentages: NiO 15-20%, Ga 2 O 3 5-10%, RuO 2 0.1-1%, Al 2 O 3 30-40%, CaO 30-40%, based on the total mass of the metal element oxides contained in the catalyst being 100%.

3. The methane reforming reaction catalyst according to claim 1, characterized in that, for the Ni-Ga alloy, the molar ratio of Ni:Ga is 1.6:1 to 6:1; and / or The RuO x nanoparticles are oxygen-rich vacancy RuO x nanoparticles, where x ranges from 0.5 to 2; and / or The high-alumina cement, wherein the content of Al 2 O 3 is not less than 45 wt%; preferably, it further contains not more than 50 wt% of calcium oxide.

4. A preparation method of the methane reforming reaction catalyst according to any one of claims 1-3, characterized in that, the preparation of the catalyst precursor includes the following steps: S1: Add an excessive amount of urea to the mixed salt solution of Ni, Ga, and Ru and mix evenly. Then, conduct a high-temperature hydrothermal reaction in a high-pressure reaction kettle. After the reaction ends, recover the precipitate and dry it to obtain a mixture of Ni-Ga precursor and RuO x nanoparticle precursor mixture; S2: Mix the precursor mixture obtained in step S1 with high alumina cement evenly and grind thoroughly; S3: Add an appropriate amount of pure water to the ground mixture obtained in step S2 and knead until it becomes soft, then extrude into shape, cut and dry to obtain the catalyst precursor.

5. The preparation method according to claim 4, characterized in that, in step S1, the molar ratio of urea:(Ni+Ga+Ru) is 1.2:1 to 1.5:1; and / or the Ni, Ga, Ru mixed salt solution in step S1 is an aqueous solution of Ni, Ga, Ru mixed salts; preferably, the total concentration of Ni, Ga, Ru in the aqueous solution is 0.1-5 mol / L; preferably, in the Ni, Ga, Ru mixed salt solution, the molar ratio of Ni, Ga, Ru is 1-5:1:0.1-0.5, preferably 1.6-3:1:0.15-0.45; preferably, for the Ni, Ga, Ru mixed salts, the salts therein are selected from at least one of nitrates, chlorides, etc.

6. The preparation method according to claim 4, characterized in that, in the high-temperature hydrothermal reaction in step S1, the reaction temperature is 160-190 °C and the reaction time is 18-48 h; for the high-temperature hydrothermal reaction, the reaction pressure is 0.8-5 MPa.

7. The preparation method according to claim 4, characterized in that, in step S2, the mass ratio of the precursor mixture to high alumina cement is 1:1.5 to 1:4; and / or the average particle size of the powder obtained after grinding in step S2 is not more than 200 μm; and / or the shape of the catalyst precursor extruded in step S3 is selected from any one of bar-shaped, cylindrical, single-hole cylindrical, multi-hole cylindrical, circular ring-shaped, wheel-shaped.

8. A preparation method of the methane reforming reaction catalyst according to any one of claims 1-3, characterized in that, it includes subjecting the catalyst precursor to high-temperature secondary phase transition heat treatment to obtain the catalyst product; the catalyst precursor is prepared by the method according to any one of claims 4-7; Preferably, the high-temperature secondary phase transformation heat treatment consists of four consecutive heat treatment stages, namely, a dehydration stage, an alloy phase transformation stage, an Al 2 O 3 phase transformation stage, and a cooling stage.

9. The preparation method according to claim 8, characterized in that, in the dehydration section, the temperature is 120-150 °C, the pressure is slightly positive pressure, the atmosphere is an inert atmosphere, and the treatment time is 6-8 h; and / or The alloy phase transition section has a temperature of 700 - 800 °C, a slightly positive pressure, a reducing atmosphere, and a treatment time of 4 - 6 h; and / or The Al 2 O 3 phase transition section, with a temperature of 850 to 1000 °C, a slightly positive pressure, an inert atmosphere, and a treatment time of 4 to 6 h; and / or The heating rate used in the high-temperature secondary phase transition heat treatment is not higher than 8 °C / min; and / or In the cooling section, the cooling rate is not higher than 10 °C / min, the pressure is slightly positive, the atmosphere is an inert atmosphere, and the furnace can be taken out only when the temperature drops below 150 °C.

10. Use of the methane reforming reaction catalyst according to any one of claims 1 - 3, or the methane reforming reaction catalyst prepared by the method according to any one of claims 4 - 7, or the methane reforming reaction catalyst prepared by the method according to claim 8 or 9 in steam reforming of methane and dry reforming reaction.

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