Silver-containing catalyst, preparation method and application thereof, and methane dry reforming method

Abstract

The invention discloses a silver-containing catalyst and a preparation method and application thereof and a methane dry reforming method, the catalyst comprises a YSZ carrier and an active component loaded on the YSZ carrier, the elements of the active component comprise a metal element M and Ag, and the metal element M is selected from group VIII elements. The catalyst disclosed by the invention has the characteristics of high stability, long service life and the like, is suitable for being used in the field of methane reforming, can keep the reaction activity in a long period (as long as 100 hours) under a high-pressure condition (10-40bar), and has excellent carbon deposition resistance.

Description

Technical Field

[0001] This invention relates to a silver-containing catalyst, its preparation method and application, and a method for dry reforming methane. Background Technology

[0002] Methane, a major component of natural gas from oil and gas fields, shale gas, coalbed methane, and combustible ice, is an important natural resource characterized by abundant reserves and wide availability. Methane can be used for heating or power generation, and can also be converted into syngas as a chemical feedstock for the production of liquid fuels and chemicals. Some natural gas fields contain high levels of carbon dioxide; if this carbon dioxide can be utilized at a high value through catalytic conversion, it can not only save separation costs but also reduce carbon dioxide emissions, representing a multi-beneficial approach. Methane dry gas reforming can simultaneously convert two greenhouse gases, CH4 and CO2, into syngas with a wide range of applications. It boasts advantages such as high resource utilization, low energy consumption and operating costs, and produces syngas with a low H2 / CO ratio, making it suitable as feedstock for olefin hydroformylation, acetic acid, dimethyl ether, and olefin production.

[0003] Most research on dry methane reforming (DRM) catalysts focuses on atmospheric pressure conditions. Conducting this reaction at atmospheric pressure is energy-intensive and requires significant investment. Considering that methane feedstock is stored under high pressure and the syngas is also used at high pressure (10-40 bar) to produce downstream products, conducting this reaction under high pressure is more economically advantageous. Operating at high pressure saves on expensive compression processes and equipment investment, significantly reduces operating costs, and also improves reactor conversion efficiency.

[0004] Methane steam reforming is a relatively mature industrial process, with an H2 / CO ratio of approximately 3 in the products. However, this ratio of syngas is too high for the Fischer-Tropsch synthesis process, requiring an additional water-gas shift process to reduce the H2 ratio. In industrial production, to prevent catalyst coking, a higher H2O / CH4 ratio (2.5-3.0) is used as feedstock, but excessive H2O leads to higher energy consumption. DRM has a larger coking zone than methane steam reforming, necessitating the development of novel catalysts. Currently, the main problem is the instability of DRM catalysts, which are prone to sintering and coking during the reaction, leading to catalyst deactivation, pulverization, and reaction tube blockage. Under high pressure, the thermodynamic coking zone expands, and surface coking on the catalyst intensifies; kinetically, coking formation is also accelerated, and coking precursors are generated from methane cracking, placing higher demands on the catalyst's anti-coking performance, which is a major challenge in its development. Therefore, developing sinter-free, coking-free, and cost-effective high-pressure catalysts is crucial for the industrial application of DRM.

[0005] Numerous metal catalysts have been reported in DRM catalyst research, primarily including transition metal and noble metal systems. Compared to transition metal catalysts (Co and Ni), noble metals (such as Rh, Pt, Ir, Pd, and Ru) exhibit higher catalytic activity and reaction stability in DRM reactions; however, their limited resources and high cost restrict their large-scale application. Inexpensive and readily available transition metals (Ni and Co) remain the optimal choice for industry as catalysts.

[0006] Among the existing patented technologies, CN117085691A, CN115445628A, and CN117049474A mainly use Ni as the active component and change the support. Their catalysts can achieve stable reactions with high conversion rates under normal pressure, but they are prone to carbon deposition under high pressure. The initial catalytic activity of Ni-based catalysts is comparable to that of noble metal-based catalysts, but due to the formation of coke and catalytic nickel particle aggregation on the surface of active Ni, carbon deposition is easily achieved during the DRM reaction.

[0007] In the existing technology, there is limited research on catalysts for long-term anti-carbon deposition in methane catalytic reforming under high pressure conditions. Therefore, designing a catalyst with controllable structure, stable performance and long-term anti-carbon deposition properties has important application value. Summary of the Invention

[0008] To address the aforementioned shortcomings of the prior art, the present invention aims to provide a silver-containing catalyst, its preparation method and application, and a methane dry reforming method. This catalyst exhibits high stability against carbon deposition reactions and can be applied in methane reforming to achieve long-cycle (up to 100 hours) stable operation of methane reforming reactions such as dry methane reforming (DRM), methane steam reforming, and combined methane reforming.

[0009] To achieve the above objectives, the present invention provides a silver-containing catalyst, the catalyst comprising a YSZ support and an active component supported on the YSZ support, wherein the active component comprises metal elements M and Ag, and the metal element M is selected from group VIII elements.

[0010] A second aspect of the present invention provides a method for preparing a silver-containing catalyst, the method comprising:

[0011] The solution containing compounds M and Ag was impregnated with the YSZ support; the resulting solid was then dried and reduced-calcined.

[0012] A third aspect of the present invention provides a silver-containing catalyst prepared by the method described herein.

[0013] A fourth aspect of the present invention provides the application of the catalyst described herein in methane reforming.

[0014] A fifth aspect of the present invention provides a method for dry reforming methane, the method comprising: reacting methane and carbon dioxide in the presence of the catalyst described in the present invention.

[0015] The catalyst described in this invention has the characteristics of high stability and long service life, and is suitable for use in the field of methane reforming. The catalyst can maintain its reaction activity for a long period (up to 100h) under high pressure conditions (10-40 bar) and has excellent anti-carbon deposition performance. Attached Figure Description

[0016] Figure 1 These are energy-dispersive X-ray spectroscopy (EDS-mapping) images of the catalyst in Example 1 obtained by scanning electron microscopy (SEM).

[0017] Figure 2 This is an energy-dispersive X-ray spectroscopy (EDS-mapping) image of the catalyst in Comparative Example 2 using a scanning electron microscope (SEM).

[0018] Figure 3 The X-ray diffraction (XRD) patterns of the catalysts in Examples 1-5 and Comparative Examples 1-2 after 150 h of high-pressure reaction in methane dry reforming are shown.

[0019] Figure 4 Thermogravimetric analysis (TGA) curves of the catalysts in Examples 1-5 and Comparative Examples 1-2 after 150 h of high-pressure reaction in methane dry reforming.

[0020] Table 1 shows the catalytic reaction performance of Examples 1-8 and the comparative examples, including data such as methane conversion rate, carbon dioxide conversion rate and deactivation rate, and the amount of carbon deposited on the catalyst after 150 hours of reaction. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. With regard to numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] The specific embodiments of the present invention will be described in detail below. However, it should be noted that the scope of protection of the present invention is not limited to these specific embodiments, but is determined by the claims in the appendix.

[0023] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0024] When this specification uses the prefixes "known to those skilled in the art," "prior art," or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those conventionally used in the art at the time the invention was proposed, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0025] It should be noted that the two or more aspects (or embodiments) disclosed in the context of this specification can be arbitrarily combined with each other, and the resulting technical solutions (such as methods or systems) are part of the original disclosure of this specification and also fall within the protection scope of this invention.

[0026] This invention provides a silver-containing catalyst, the catalyst comprising a YSZ support and an active component supported on the YSZ support, the active component comprising metal elements M and Ag, wherein metal element M is selected from group VIII elements.

[0027] The catalyst of this invention has the characteristics of high stability and long service life, and is particularly suitable for use in the field of methane reforming. The catalyst can maintain its reaction activity for a long period of time under high pressure and has strong anti-carbon deposition performance.

[0028] In this invention, it is understood that the YSZ support refers to yttrium-doped zirconium oxide, also known as yttrium-stabilized zirconium oxide.

[0029] In this invention, the range of M that can be selected is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, M can be selected from one or more of Co, Ni, Rh, Ir, Pd, Pt, and Ru; preferably, M is selected from Co and / or Ni.

[0030] In this invention, the metal elements M, Ag and the metal species in the YSZ carrier do not form an alloy after reduction treatment. The reduced M and Ag exist in the form of elemental metals. It can be understood that the metal elements M, Ag and YSZ do not form an alloy after reduction treatment, meaning that the metal elements M, Ag and YSZ do not form an alloy or solid solution at the atomic scale, and there is a clear interface between the three.

[0031] In this invention, the content of M, Ag, and YSZ can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of this invention.

[0032] According to a preferred embodiment of the present invention, the content of M, based on the total weight of the catalyst, is 0.1-8 wt.%, for example, 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, or 7 wt.%.

[0033] According to a preferred embodiment of the present invention, the content of Ag, based on the total weight of the catalyst, is 0.5-20 wt.%, for example, 1 wt.%, 3 wt.%, 5 wt.%, 7 wt.%, 9 wt.%, 11 wt.%, 13 wt.%, 15 wt.%, 17 wt.%, or 19 wt.%.

[0034] According to a preferred embodiment of the present invention, the content of YSZ support is 70-99 wt.% based on the total weight of the catalyst, for example, 72 wt.%, 75 wt.%, 78 wt.%, 80 wt.%, 82 wt.%, 85 wt.%, 88 wt.%, 90 wt.%, 92 wt.%, or 95 wt.%.

[0035] In this invention, the catalyst composition is calculated based on the amount of feed.

[0036] The catalysts using the content ranges of M, Ag, and YSZ supports described in the aforementioned embodiments have the characteristics of high stability and long service life, and are particularly suitable for use in the field of methane reforming. The catalysts can maintain their reaction activity for a long period of time under high pressure and have strong anti-carbon deposition properties.

[0037] In this invention, the mass ratio of Ag to M is not particularly limited. Any suitable mass ratio can be selected as long as it can achieve the purpose of this invention. According to a preferred embodiment of this invention, the mass ratio of Ag to M is (0.2-20):1, for example, 0.5:1, 0.8:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 10:1, 12:1, 14:1, 16:1 or 18:1.

[0038] In this invention, the specific surface area of ​​the support in the catalyst can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the specific surface area of ​​the support in the catalyst is 10-150 m². 2 / g, preferably 30-100m 2 / g.

[0039] In this invention, the pore volume of the support in the catalyst can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the pore volume of the support in the catalyst is 0.05-0.40 cm³. 3 / g.

[0040] In this invention, there are no special requirements for the particle size of the metal species reduced from the active components including Ag and M on the catalyst support. This is an illustrative example and does not limit the scope of the invention. According to a preferred embodiment of the invention, the particle size of the metal species reduced from the active components including Ag and M on the catalyst support is in the nanometer range, preferably 1-100 nm.

[0041] In this invention, the catalyst structure can be selected from a wide range of types. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the catalyst has a spherical microstructure.

[0042] In this invention, the yttrium oxide content in the YSZ support can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the molar percentage of yttrium oxide in the YSZ support is 2-10 mol.%, preferably 4-8 mol.%.

[0043] In this invention, the crystal system of the YSZ support can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the crystal system of the YSZ support is a tetragonal phase structure.

[0044] In this invention, there are no special requirements for the preparation method of the silver-containing catalyst; any method capable of preparing a catalyst with the aforementioned characteristics of this invention can be selected. According to a preferred embodiment of this invention, this invention provides a method for preparing a silver-containing catalyst, the method comprising:

[0045] The solution containing compounds M and Ag was impregnated with the YSZ support; the resulting solid was then dried and reduced-calcined.

[0046] According to the present invention, it is understood that the solvent in the solution containing compound M and compound Ag is generally water, but other organic solvents may be added as needed.

[0047] In this invention, the specific surface area of ​​the YSZ carrier can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the specific surface area of ​​the YSZ carrier is 10-150 m². 2 / g, preferably 30-100m 2 / g, compared to the 1-10m of existing technologies 2 The YSZ carrier of this invention has a significant advantage in specific surface area, with a surface area of ​​ / g.

[0048] In this invention, the pore volume of the YSZ carrier can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the pore volume of the YSZ carrier is 0.05-0.40 cm³. 3 / g.

[0049] In this invention, the molar percentage of yttrium oxide in the YSZ carrier can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the molar percentage of yttrium oxide in the YSZ carrier is 2-10 mol.%, preferably 4-8 mol.%. In this invention, the content of each component in the YSZ carrier is obtained by ICP elemental analysis, which is consistent with the feed ratio.

[0050] In this invention, the crystal system of the YSZ support can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the crystal system of the YSZ support is a tetragonal phase structure.

[0051] In this invention, the preparation method of the YSZ carrier can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the preparation method of the YSZ carrier includes:

[0052] In the presence of an alkaline substance, a Zr source, a Y source, and a strong cationic polyelectrolyte are mixed to form an alkaline solution, followed by a hydrothermal precipitation reaction. The resulting solid is then dried and calcined to obtain a YSZ support.

[0053] In this invention, the strong cationic polyelectrolyte is not specifically limited; any suitable strong cationic polyelectrolyte can be selected as long as it can achieve the purpose of this invention.

[0054] According to a preferred embodiment of the present invention, the number-average molecular weight of the strong cationic polyelectrolyte is 10,000 to 12 million.

[0055] According to a preferred embodiment of the present invention, the strong cationic polyelectrolyte is a cationic polymer with repeating units containing electrolyte groups such as amine, imine, tertiary amine, and quaternary ammonium salt (amino). These groups are completely dissociated in aqueous solution (water) and are positively charged. It is easily adsorbed onto the surface of particles and can play a role in flocculation and pore formation.

[0056] In this invention, the range of strong cationic polyelectrolytes is relatively wide. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the strong cationic polyelectrolyte is selected from one or more of polydiallyldimethylammonium chloride (PDDA), polymethacryloyloxyethyltrimethylammonium chloride (PDMC), polyhexammonium bromide, cationic polyacrylamide, polyhydroxyethyl cellulose ether quaternary ammonium salt, polyethyleneimine and its hydrochloride, and polyvinylpyridine.

[0057] In this invention, the total amount of Zr and Y elements in the solution and the weight ratio of the strong cationic polyelectrolyte can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the weight ratio of the total amount of Zr and Y elements in the solution and the strong cationic polyelectrolyte is 1:(0.1-6), for example, 1:0.5, 1:1.5, 1:2.5, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, etc.

[0058] In this invention, the Zr source is not specifically limited. Any suitable Zr source can be selected as long as it can achieve the purpose of this invention. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the Zr source is selected from one or more of ZrO(NO3)2, ZrOCl2·8H2O, etc.

[0059] In this invention, the Y source is not specifically limited. Any suitable Y source can be selected as long as it can achieve the purpose of this invention. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the Y source is selected from one or more of Y(CH3COO)3·4H2O, Y(NO3)3·6H2O, YCl3·6H2O, etc.

[0060] In this invention, the molar ratio of the Zr source to the Y source can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the molar ratio of the Zr source to the Y source is 1:(0.04-0.5).

[0061] In this invention, the total amount of Zr and Y elements in the solution and the molar ratio of the alkaline substance can be selected within a wide range, with the aim of making the solution alkaline. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the molar ratio of the total amount of Zr and Y elements in the solution to the alkaline substance is 1:(0.5-10), for example, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5 or 1:8.

[0062] In this invention, there are no special requirements for the pH of the alkaline solution. This is an illustrative example and does not limit the scope of the invention. According to a preferred embodiment of the invention, the pH value of the alkaline solution is greater than 7.

[0063] In this invention, any alkaline substance capable of producing an alkaline solution can be used, such as one or more of urea, ammonia, sodium carbonate, sodium bicarbonate, sodium hydroxide, and potassium hydroxide.

[0064] In this invention, the concentration of the Zr source in the solution can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the concentration of the Zr source in the solution is 0.02-6.5 mol / L, for example, 0.5 mol / L, 0.8 mol / L, 1.2 mol / L, 1.8 mol / L, 2.2 mol / L, 2.8 mol / L, 3.2 mol / L, 3.8 mol / L, 4.2 mol / L, 4.8 mol / L, 5.2 mol / L, 5.8 mol / L, 6.2 mol / L, etc.

[0065] In this invention, the temperature of the hydrothermal reaction is not particularly limited. As long as the purpose of this invention can be achieved, any suitable temperature of the hydrothermal reaction can be selected. According to a preferred embodiment of this invention, the temperature of the hydrothermal reaction is 130-160°C, for example, 130°C, 140°C, 150°C, or 160°C. In the example, 150°C is used as an example to illustrate the advantages of this invention, but this does not limit the scope of this invention.

[0066] In this invention, the hydrothermal reaction time is not particularly limited. As long as the purpose of this invention can be achieved, any suitable hydrothermal reaction time can be selected. Specifically, it can be selected and determined according to the temperature. According to a preferred embodiment of this invention, the hydrothermal reaction time is 10-15 hours. In the example, 12 hours is used as an example to illustrate the advantages of this invention, but this does not limit the scope of this invention.

[0067] In this invention, the drying temperature is not specifically limited. Any suitable drying temperature can be selected as long as it can achieve the purpose of this invention. According to a preferred embodiment of this invention, the drying temperature is 60-100℃. In the example, 90℃ is used as an example to illustrate the advantages of this invention, but this does not limit the scope of this invention.

[0068] In this invention, the drying time is not specifically limited. Any suitable drying time can be selected as long as the purpose of this invention can be achieved. Specifically, it can be selected and determined according to the temperature. According to a preferred embodiment of this invention, the drying time is 3-24 hours. In the example, 12 hours is used as an example to illustrate the advantages of this invention, but this does not limit the scope of this invention.

[0069] In this invention, the roasting temperature is not particularly limited. Any suitable roasting temperature can be selected as long as the purpose of this invention can be achieved. According to a preferred embodiment of this invention, the roasting temperature is 600-1200℃, for example, 630℃, 700℃, 750℃, 800℃, 850℃, 900℃, 1000℃, or 1200℃. In the embodiment, 850℃ is used as an example to illustrate the advantages of this invention, but this does not limit the scope of this invention.

[0070] In this invention, the roasting time is not specifically limited. Any suitable roasting time can be selected as long as the purpose of this invention can be achieved. Specifically, it can be selected and determined according to the temperature. According to a preferred embodiment of this invention, the roasting time is 3-8 hours. In the example, 5 hours is used as an example to illustrate the advantages of this invention, but this does not limit the scope of this invention.

[0071] The YSZ support obtained by the method of the present invention has advantages in physicochemical characteristics such as specific surface area, thereby giving it good thermal stability, chemical stability, and high-temperature oxygen ion conduction. In the methane reforming system, the excellent thermal and chemical stability of YSZ obtained by the method of the present invention plays an important role in the preparation of catalysts with good stability, resistance to sintering and carbon deposition.

[0072] In this invention, after the hydrothermal reaction, in order to obtain a solid, solid-liquid filtration, centrifugation, washing, or other operations can be performed to obtain a clean solid.

[0073] In this invention, there are no special requirements for the contact impregnation conditions between the solution containing compound M and compound Ag and the YSZ support. This is an illustrative example and does not limit the scope of the invention. According to a preferred embodiment of the invention, the amounts of compound M, compound Ag and YSZ support are such that the content of M is 0.1-8 wt.%, for example 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.% or 7 wt.%, based on the total weight of the catalyst.

[0074] According to a preferred embodiment of the present invention, the amounts of compound M, compound Ag, and YSZ support are such that the content of Ag, based on the total weight of the catalyst, is 0.5-20 wt.%, for example, 1 wt.%, 3 wt.%, 5 wt.%, 7 wt.%, 9 wt.%, 11 wt.%, 13 wt.%, 15 wt.%, 17 wt.%, or 19 wt.%.

[0075] According to a preferred embodiment of the present invention, the amounts of compound M, compound Ag, and YSZ support, based on the total weight of the catalyst, are such that the content of YSZ support, based on the total weight of the catalyst, is 70-99 wt.%, for example, 72 wt.%, 75 wt.%, 78 wt.%, 80 wt.%, 82 wt.%, 85 wt.%, 88 wt.%, 90 wt.%, 92 wt.%, or 95 wt.%.

[0076] In this invention, the mass ratio of Ag to M is not particularly limited. Any suitable mass ratio can be selected as long as it can achieve the purpose of this invention. According to a preferred embodiment of this invention, the amount of compound M and compound Ag is such that the mass ratio of Ag to M is (0.2-20):1, for example, 0.5:1, 0.8:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 10:1, 12:1, 14:1, 16:1 or 18:1.

[0077] In this invention, the temperature of the contact immersion is not particularly limited; any suitable conditions can be selected as long as the purpose of this invention can be achieved.

[0078] In this invention, there are no special requirements for the contact immersion time; the specific time is selected and determined based on factors such as temperature.

[0079] In this invention, the contact impregnation method is not particularly limited. Any suitable contact impregnation method can be selected as long as it can achieve the purpose of this invention. According to a preferred embodiment of this invention, the contact impregnation method is a co-impregnation method.

[0080] In this invention, the drying conditions are not particularly limited. Any suitable drying conditions can be selected as long as they can achieve the purpose of this invention. According to a preferred embodiment of this invention, the drying conditions include: vacuuming and removing water in a rotary evaporator, followed by drying in an air atmosphere at 60-100°C.

[0081] In this invention, there are no special requirements for the drying time, which is selected and determined based on factors such as the drying temperature. Generally, the drying time can be 3-24 hours.

[0082] In this invention, the atmosphere for the reduction roasting can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the reduction atmosphere is a hydrogen-containing atmosphere.

[0083] In this invention, the hydrogen-containing atmosphere can be selected from a wide range. The following is an illustrative example, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the hydrogen-containing atmosphere is a hydrogen-containing atmosphere diluted with an inert gas, wherein the hydrogen content is 1-99 vol.%. In the examples, 10 vol.% is used as an example to illustrate the advantages of the invention, but it does not limit the scope of the invention.

[0084] In this invention, the conditions for reduction calcination can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the conditions for reduction calcination include: a heating rate of 1-5℃ / min, a final heating temperature of 600-900℃, and a holding time at the final temperature of 3-8h.

[0085] This invention provides a silver-containing catalyst prepared by the method described herein.

[0086] This invention provides an application of the catalyst described herein in methane reforming.

[0087] The catalyst of this invention is particularly suitable for use in the field of methane reforming, such as dry methane reforming, steam methane reforming, and combined methane reforming (simultaneous addition of water and carbon dioxide).

[0088] The present invention provides a method for dry reforming methane, the method comprising: reacting methane and carbon dioxide in the presence of the catalyst described in the present invention.

[0089] In this invention, the contact reaction conditions can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the contact conditions include pressures of 2-40 bar, such as 2 bar, 3 bar, 4 bar, 5 bar, 6 bar, 7 bar, 8 bar, 9 bar, 10 bar, 11 bar, 12 bar, 13 bar, 14 bar, 15 bar, 16 bar, 17 bar, 18 bar, 19 bar, 21 bar, 22 bar, 23 bar, 24 bar, 25 bar, 26 bar, 27 bar, 28 bar, 29 bar, 31 bar, 32 bar, 33 bar, 34 bar, 35 bar, 36 bar, 37 bar, 38 bar, 39 bar, etc. In the examples, 20 bar is used as an example to illustrate the advantages of the invention, but it does not limit the scope of the invention.

[0090] In this invention, the contact conditions can be selected from a wide range. The following is an illustrative example, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the contact conditions include a temperature of 700-900°C, such as 730°C, 800°C, 850°C, 880°C, etc. In the embodiment, 750°C is used as an example to illustrate the advantages of the invention, but it does not limit the scope of the invention.

[0091] In this invention, the molar ratio of methane to carbon dioxide can be selected from a wide range, and commonly used molar ratios can be used in this invention. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the molar ratio of methane to carbon dioxide is 1:(0.5-2).

[0092] In this invention, the gas space velocity can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the gas space velocity is 2000-90000 mL·h. -1 ·g cat -1 Preferably 3000-10000 mL·h -1 ·g cat -1 .

[0093] In this invention, the contact reaction conditions can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the contact reaction conditions include the contact reaction being carried out in the presence of a diluent.

[0094] In this invention, the diluent can be selected from a wide range of options. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the diluent is selected from one or more of SiC and SiO2.

[0095] In this invention, there are no special requirements for the mass ratio of diluent to catalyst. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the mass ratio of diluent to catalyst is 0.5-4.

[0096] In this invention, Figure 1 The image shown is an energy-dispersive X-ray spectroscopy (EDS-mapping) image of the catalyst in Example 1 obtained by scanning electron microscopy (SEM). Figure 2The image shown is an energy-dispersive X-ray spectroscopy (EDS) image of the catalyst in Comparative Example 2. Compared to Comparative Example 2, the distribution of Zr in Example 1 remained unchanged, while the introduction of the Ag promoter made the distribution of the active metal more dispersed. In Comparative Example 2, the catalyst was only loaded with active metal, and its main loading form was large spherical agglomerates. After loading the Ag promoter in Example 1, it was clearly observed that the size of the active metal particles was reduced, and they were uniformly loaded on the support surface.

[0097] In this invention, Figure 3 The XRD patterns of the catalysts in Examples 1-5 and Comparative Examples 1-2 of this invention after 150 h of high-pressure dry reforming of methane are shown in the figure. As can be seen from the figure, after 150 h of high-pressure dry reforming of methane, the catalysts in the examples of this invention do not have graphite-type carbon deposit (C) peaks after the reaction, while the catalysts in the comparative examples of this invention show graphite C peaks. It can be seen that the catalysts of this invention have excellent anti-carbon deposit performance.

[0098] In this invention, Figure 4 The thermogravimetric analysis (TGA) curves of the catalysts in Examples 1-5 and Comparative Examples 1-2 after 150 h of high-pressure reaction in methane dry reforming are shown in the figure. As can be seen from the figure, the catalysts in the examples have very little carbon deposition, while the catalysts in the comparative examples have more carbon deposition.

[0099] In this invention, Table 1 shows the rate of decrease in methane and carbon dioxide conversion rates over time in the presence of the catalyst described in this invention, as well as the amount of carbon deposited on the catalyst after 150 hours of reaction (measured by TGA analysis). Compared with catalysts of Comparative Examples 1 and 2 that were not modified with Ag promoter, the catalyst of this invention has the characteristics of strong stability and long service life. Under high pressure conditions, the catalyst of this invention can maintain its reaction activity for a long period of time and has good anti-carbon deposition performance.

[0100] In summary, the catalyst of the present invention is suitable for use in the field of methane reforming. The beneficial effects of the present invention are mainly reflected in the following: the catalyst of the present invention has advantages such as resistance to carbon deposition and sintering and good catalytic stability under high pressure reaction conditions in the field of methane reforming, and has good application prospects.

[0101] The present invention will be described in detail below through embodiments. In the following embodiments,

[0102] 1. Medicines

[0103] Zirconium oxynitrate (ZrO(NO3)2, 99.5%), yttrium acetate (Y(CH3COO)2·4H2O, 99.9%), urea (CO(NH2)2, 99%), ammonia, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, polydiallyldimethylammonium chloride (PDDA), polymethacryloyloxyethyltrimethylammonium chloride (PDMC), polyhexammonium bromide, cationic polyacrylamide, polyhydroxyethyl cellulose ether quaternary ammonium salt, polyethyleneimine or other compounds. Hydrochloride, polyvinylpyridine, cobalt acetate hexahydrate (Co(CH3COO)2·6H2O, 98%), cobalt nitrate hexahydrate (Co(NO3)2·6H2O, 99.99%), nickel acetate hexahydrate (Ni(CH3COO)2·6H2O, 99.99%), nickel nitrate hexahydrate (Ni(NO3)2·6H2O, 99.99%), silver nitrate (AgNO3, 99.8%), silver acetate (AgCH3COO, 99%).

[0104] 2. Characterization Testing Methods

[0105] (1) X-ray diffraction (XRD)

[0106] X-ray diffraction (XRD) was used to determine the crystal structure of the catalyst. XRD (Rigaku D / Max-RC) analysis was performed on the catalyst before and after the reaction. Cu-excited K α X-ray, 40kW, 100mA The test speed is 1° / min, and the angle range is 2θ = 10-80°.

[0107] (2) Field emission scanning electron microscopy (SEM) and area scanning component analysis (EDS-mapping)

[0108] The microscopic surface morphology of the catalyst was observed using field emission scanning electron microscopy (FE-SEM), and the distribution of metal elements on the catalyst surface was analyzed using energy-dispersive X-ray spectroscopy (EDS-mapping). A GeminiSEM500 instrument was used. Before measurement, the catalyst underwent pretreatment. The catalyst was completely dispersed in ethanol, dropped onto a silicon wafer, and placed in an oven until the ethanol was completely dried. The silicon wafer was then transferred to the sample stage, fixed with conductive adhesive, and the distribution of metal elements and microstructure were observed using the instrument.

[0109] (3) Thermal analyzer (TGA-DSC)

[0110] Thermal stability of catalysts can be assessed by determining the relationship between catalyst mass and temperature changes, surface carbon content, and coke type using thermal analysis (TGA-DSC). A TGA Pyris 1 (Perkin Elmer) instrument was employed. The catalyst was placed in air and heated to 120°C at a rate of 10°C / min, then held at that temperature for 30 min to remove moisture and other impurities. Subsequently, the temperature was increased to 870°C at a rate of 10°C / min and held at that temperature for 30 min to ensure complete removal of coke. The change in catalyst mass was recorded.

[0111] (4) The specific surface area and pore volume of the carrier are tested by the low temperature N2 adsorption-desorption isotherm method.

[0112] 3. Calculation method

[0113] The composition of the outlet gas was analyzed using the normalization method.

[0114] The CH4 conversion rate is calculated as follows:

[0115]

[0116] The CO2 conversion rate is calculated as follows:

[0117]

[0118] The H2 / CO ratio is calculated as follows:

[0119]

[0120] Preparation Example 1

[0121] Preparation of YSZ support:

[0122] Weigh 6.41 g ZrO(NO3)2, 0.82 g Y(CH3COO)3·4H2O, 9.01 g of a 20% aqueous solution of polydiallyldimethylammonium chloride (number average molecular weight 200,000-350,000), and 8.00 g urea into a beaker. Add 150 mL of deionized water and stir for 5 h to fully dissolve and obtain an alkaline solution (pH 7.3). Transfer the solution to a high-pressure hydrothermal reactor lined with polytetrafluoroethylene and heat in an oven at 90 °C for 12 h. Filter the reaction product to obtain a precipitate. Wash the precipitate several times with deionized water and dry it in an oven at 150 °C for 12 h. Place the dried precipitate in a muffle furnace and heat to 850 °C, then calcine for 5 h. Obtain a YSZ support with a Y2O3 molar content of 4 mol.%, which has a tetragonal phase structure and a specific surface area of ​​93 m². 2 / g, pore volume 0.35cm 3 / g.

[0123] Preparation Example 2

[0124] Preparation of YSZ support:

[0125] Weigh 6.40 g ZrO(NO3)2, 1.06 g Y(CH3COO)3·4H2O, 1.55 g cationic polyacrylamide (number average molecular weight 8-12 million), and 10.51 g sodium bicarbonate into a beaker. Add 150 mL of deionized water and stir for 5 h to fully dissolve and obtain an alkaline solution (pH 7.8). Transfer the solution to a polytetrafluoroethylene-lined high-pressure hydrothermal reactor and heat in an oven at 150 °C for 12 h. Filter the reaction product to obtain a precipitate. Wash the precipitate several times with deionized water and dry it in an oven at 90 °C for 12 h. Place the dried precipitate in a muffle furnace and heat to 900 °C, then calcine for 5 h. Obtain a YSZ support with a Y2O3 content of 5 mol.%, which has a tetragonal phase structure and a specific surface area of ​​55 m². 2 / g, pore volume 0.22cm 3 / g.

[0126] Preparation Example 3

[0127] Preparation of YSZ support:

[0128] Weigh 6.39 g of ZrO(NO3)2, 0.92 g of Y(CH3COO)3·4H2O, 6.66 g of a 50% aqueous solution of polyethyleneimine (number average molecular weight 10,000-70,000), and 2.40 g of sodium hydroxide into a beaker. Add 150 mL of deionized water and stir for 5 h to fully dissolve and obtain an alkaline solution (pH 10.1). Transfer the solution to a high-pressure hydrothermal reactor lined with polytetrafluoroethylene and heat in an oven at 150 °C for 12 h. Filter the reaction product to obtain a precipitate. Wash the precipitate several times with deionized water and dry it in an oven at 90 °C for 12 h. Place the dried precipitate in a muffle furnace and heat to 900 °C, then calcine for 5 h. Obtain a YSZ support with a Y2O3 content of 4.5 mol.%, which has a tetragonal phase structure and a specific surface area of ​​66 m². 2 / g, pore volume 0.26cm 3 / g.

[0129] Preparation Example 4

[0130] Preparation of YSZ support:

[0131] Weigh 6.38 g ZrO(NO3)2, 1.76 g Y(CH3COO)3·4H2O, 35.36 g 20% ​​aqueous solution of polyhydroxyethyl cellulose ether quaternary ammonium salt (number average molecular weight 250,000-600,000), and 9.82 g sodium carbonate into a beaker. Add 150 mL deionized water and stir for 5 h to fully dissolve and obtain an alkaline solution (pH approximately 7.6). Transfer the solution to a high-pressure hydrothermal reactor lined with polytetrafluoroethylene and heat in an oven at 150 °C for 12 h. Filter the reaction product to obtain a precipitate. Wash the precipitate several times with deionized water and dry it in an oven at 90 °C for 12 h. Place the dried precipitate in a muffle furnace and heat to 850 °C, then calcine for 5 h. Obtain a YSZ support with a Y2O3 content of 8 mol.%, which has a tetragonal phase structure and a specific surface area of ​​39 m². 2 / g, pore volume 0.14cm 3 / g.

[0132] Preparation Example 5

[0133] Preparation of YSZ support:

[0134] Weigh 2.14 g ZrO(NO3)2, 0.44 g Y(CH3COO)3·4H2O, 2.68 g polymethacryloyloxyethyltrimethylammonium chloride (PDMC) (number average molecular weight 1,000,000-1,400,000), and 1.28 g ammonia water (28% mass concentration) into a beaker. Add 150 mL deionized water and stir for 5 h to fully dissolve and obtain an alkaline solution (pH 8.5). Transfer the solution to a high-pressure hydrothermal reactor lined with polytetrafluoroethylene and heat in an oven at 150 °C for 12 h. Filter the reaction product to obtain a precipitate. Wash the precipitate several times with deionized water and dry it in an oven at 90 °C for 12 h. Place the dried precipitate in a muffle furnace and heat to 850 °C, then calcine for 5 h. Obtain a YSZ support with a Y2O3 content of 6 mol.%, which has a tetragonal phase structure and a specific surface area of ​​43 m². 2 / g, pore volume 0.16cm 3 / g.

[0135] Preparation Example 6

[0136] Similar to Preparation Example 1, except that the cationic electrolyte used is polyquaternary ammonium salt-7 (molecular formula C). 11 H 21 ClN2O). The amount of cationic electrolyte used was the same as in Preparation Example 1.

[0137] A YSZ support with a Y2O3 content of 8 mol.% was obtained. This support has a tetragonal phase structure and a specific surface area of ​​16 m². 2 / g, pore volume 0.12cm 3 / g.

[0138] The structural formula of polyquaternium-7 is:

[0139] Example 1

[0140] Metal was loaded onto the YSZ support used in Preparation Example 3:

[0141] 0.3114 g of Co(CH3COO)2·4H2O, 0.2123 g of AgNO3, and 150 ml of deionized water were placed in a beaker and stirred thoroughly at 25 °C for 5 h to dissolve and obtain a mixed solution. 1.00 g of YSZ support was added to this solution and stirred for 5 h to mix evenly. The suspension was poured into a flask and placed in a rotary evaporator at 70 °C under vacuum for rotary evaporation. The solid obtained after rotary evaporation was scraped off the inner wall of a flask and placed in a crucible, then placed in a constant temperature drying oven at 90 °C for 12 h to dry thoroughly. N2 was introduced into a tube furnace and the temperature was increased to 700 °C at a rate of 5 °C / min. The gas was then switched to a 10 vol.% H2 / Ar mixture, and the catalyst was reduced for 5 h.

[0142] The supported active metal catalyst Co-Ag / YSZ was obtained, wherein,

[0143] The content of Ag was 11.16 wt.%, the content of Co was 6.10 wt.%, and the content of YSZ was 82.74 wt.%. FE-SEM observation showed that the Co-Ag metal species particles on the YSZ support surface mainly exhibited a spherical morphology with a particle size of 20-80 nm.

[0144] Reforming reaction:

[0145] Mix 1.00 g of SiC diluent with 1.00 g of catalyst until homogeneous, then pack the mixture into the reactor. Control the flow rates of methane and carbon dioxide at 30 mL / min each, and the reaction space velocity at 3600 mL·h. -1 ·g cat -1 The pressure was 20 bar and the temperature was 750℃. The results are shown in Table 1.

[0146] Example 2

[0147] Metal was loaded onto the YSZ support used in Preparation Example 4:

[0148] 0.1503 g Ni(NO3)2·6H2O, 0.0098 g AgNO3, and 150 ml deionized water were placed in a beaker and stirred thoroughly at 30 °C for 7 h to dissolve and obtain a mixed solution. 1.00 g YSZ support was added to this solution and stirred for 5 h to mix evenly. The suspension was poured into a flask and placed in a rotary evaporator at 75 °C under vacuum for rotary evaporation. The solid obtained after rotary evaporation was scraped off the inner wall of a flask and placed in a crucible, then placed in a constant temperature drying oven at 85 °C for 12 h to dry thoroughly. N2 was introduced into a tube furnace and the temperature was increased to 700 °C at a rate of 5 °C / min. The gas was then switched to a 10 vol.% H2 / Ar mixture, and the catalyst was reduced for 5 h.

[0149] Ni-Ag / YSZ, a catalyst supported on an active metal, was obtained.

[0150] The content of Ni is 2.93 wt.%, the content of Ag is 0.60 wt.%, and the content of YSZ is 96.47 wt.%. The particle size of Ni-Ag metal species on the YSZ support surface is 30-60 nm.

[0151] Evaluation conditions for methane dry reforming reaction:

[0152] Mix 1.00 g of SiC diluent with 1.00 g of catalyst until homogeneous, then pack the mixture into the reactor. Control the flow rates of methane and carbon dioxide at 50 mL / min each, and the reaction space velocity at 6000 mL·h. -1 ·g cat -1 The pressure was 20 bar and the temperature was 750℃. The results are shown in Table 1.

[0153] Example 3

[0154] Metal was loaded onto the YSZ support used in Preparation Example 5:

[0155] 0.0067 g Co(NO3)2·6H2O, 0.0076 g Ni(NO3)2·6H2O, 0.0098 g AgNO3, and 150 ml deionized water were placed in a beaker and stirred thoroughly at 25 °C for 10 h to dissolve and obtain a mixed solution. 1.00 g YSZ support was added to this solution and stirred for 5 h to mix evenly. The suspension was poured into a flask and placed in a rotary evaporator at 70 °C under vacuum for rotary evaporation. The solid obtained after rotary evaporation was scraped off the inner wall of a flask and placed in a crucible, then placed in a constant temperature drying oven at 80 °C for 12 h to dry thoroughly. N2 was introduced into a tube furnace and the temperature was increased to 700 °C at a rate of 5 °C / min. The gas was then switched to a 10 vol.% H2 / Ar mixture, and the catalyst was reduced for 5 h.

[0156] The supported active metal catalyst Co-Ni-Ag / YSZ was obtained, wherein,

[0157] The content of Ag is 0.62 wt.%, the content of Ni is 0.15 wt.%, the content of Co is 0.13 wt.%, and the content of YSZ is 99.10 wt.%. The particle size of the Co-Ni-Ag metal species on the YSZ carrier surface is 30-60 nm.

[0158] Evaluation conditions for methane dry reforming reaction:

[0159] Mix 2.00 g of SiC diluent with 0.60 g of catalyst until homogeneous, then pack the mixture into the reactor. Control the flow rates of methane and carbon dioxide at 30 mL / min each, and the reaction space velocity at 6000 mL·h⁻¹. -1 ·g cat -1 The pressure was 20 bar and the temperature was 750℃. The results are shown in Table 1.

[0160] Example 4

[0161] Metal was loaded onto the YSZ support used in Preparation Example 1:

[0162] 0.1819 g of Co(NO3)2·6H2O, 0.3185 g of AgNO3, and 150 ml of deionized water were placed in a beaker and stirred thoroughly at 25 °C for 10 h to dissolve and obtain a mixed solution. 1.00 g of YSZ support was added to this solution and stirred for 5 h to mix evenly. The suspension was poured into a flask and placed in a rotary evaporator at 65 °C under vacuum for rotary evaporation. The solid obtained after rotary evaporation was scraped off the inner wall of a flask and placed in a crucible. It was then placed in a constant temperature drying oven at 80 °C for 12 h to dry thoroughly. N2 was introduced into a tube furnace and the temperature was increased to 700 °C at a rate of 5 °C / min. The gas was then switched to a 10 vol.% H2 / Ar mixture, and the catalyst was reduced for 5 h.

[0163] The supported active metal catalyst Co-Ag / YSZ was obtained, wherein,

[0164] The content of Ag is 16.33 wt.%, the content of Co is 2.97 wt.%, and the content of YSZ is 80.7 wt.%. The particle size of the Co-Ag metal species on the YSZ carrier surface is 20-90 nm.

[0165] Evaluation conditions for methane dry reforming reaction:

[0166] Mix 1.00 g of SiC diluent with 0.50 g of catalyst until homogeneous, then pack the mixture into the reactor. Control the flow rates of methane and carbon dioxide at 40 mL / min each, and the reaction space velocity at 9600 mL·h. -1 ·g cat -1， The pressure was 20 bar and the temperature was 750℃. The results are shown in Table 1.

[0167] Example 5

[0168] Metal was loaded onto the YSZ support used in Preparation Example 2:

[0169] 0.0589 g Ni(CH3COO)2·4H2O, 0.1619 g AgCH3COO, and 150 ml deionized water were placed in a beaker and stirred thoroughly at 25 °C for 6 h to dissolve and obtain a mixed solution. 1.00 g YSZ support was added to this solution and stirred for 5 h to mix evenly. The suspension was poured into a flask and placed in a rotary evaporator at 60 °C under vacuum for rotary evaporation. The solid obtained after rotary evaporation was scraped off the inner wall of a flask and placed in a crucible. It was then placed in a constant temperature drying oven at 80 °C for 12 h to dry thoroughly. N2 was introduced into a tube furnace and the temperature was increased to 700 °C at a rate of 5 °C / min. The gas was then switched to a 10 vol.% H2 / Ar mixture, and the catalyst was reduced for 5 h.

[0170] Ni-Ag / YSZ, a catalyst supported on an active metal, was obtained.

[0171] The content of Ag is 9.36 wt.%, the content of Ni is 1.28 wt.%, and the content of YSZ is 89.36 wt.%. The particle size of Ni-Ag metal species on the YSZ support surface is 30-90 nm.

[0172] Evaluation conditions for methane dry reforming reaction:

[0173] Mix 0.50 g of SiC diluent with 0.80 g of catalyst until homogeneous, then pack the mixture into the reactor. Control the flow rates of methane and carbon dioxide at 30 mL / min each, and the reaction space velocity at 4500 mL·h. -1 ·g cat -1， The pressure was 20 bar and the temperature was 750℃. The results are shown in Table 1.

[0174] Example 6

[0175] The method of Example 4 was followed, except that the support used was the YSZ support of Preparation Example 6, which had a Y2O3 content of 8 mol.% and a tetragonal phase structure with a specific surface area of ​​16 m². 2 / g, pore volume 0.12cm 3 / g, the catalyst loading was the same as in Example 4, and all other conditions were the same.

[0176] The evaluation conditions for the dry reforming reaction of methane were the same as those in Example 4. After the reforming reaction, the methane conversion rate was lower than that in Example 4, which was attributed to the lower specific surface area of ​​the support.

[0177] Example 7

[0178] The method is the same as in Example 4, except that the carrier used is conventional YSZ (with a specific surface area of ​​5 m² determined by nitrogen adsorption-desorption). 2 / g, pore volume 0.05cm 3 / g; Y2O3 molar content is 4.5 mol.%, with a tetragonal phase structure). All other conditions are the same.

[0179] The evaluation conditions for the dry reforming reaction of methane were the same as those in Example 4. After the reforming reaction, the methane conversion rate was less than 10%, which was attributed to the low specific surface area of ​​the support, low dispersion of the active component, and few active sites.

[0180] Example 8

[0181] Following the method of Example 4, the metal was loaded onto the YSZ support prepared in Example 1. The amounts of Co(NO3)2·6H2O and YSZ support remained unchanged. The only difference was that the amount of AgNO3 was 0.5848 g, and all other conditions were the same.

[0182] The supported active metal catalyst Co-Ag / YSZ was obtained, wherein,

[0183] The content of Ag was 26.38 wt.%, the content of Co was 2.62 wt.%, and the content of YSZ was 71 wt.%.

[0184] The evaluation conditions for the dry reforming reaction of methane were the same as those in Example 4. After the reforming reaction, the methane conversion rate was less than 10% because the excessive Ag loading greatly affected the catalytic effect of the Co active center, thus reducing the methane conversion rate.

[0185] Comparative Example 1

[0186] Prepared according to the method of Example 1, except that Ag is not introduced; conventional YSZ (specific surface area of ​​5 m² determined by nitrogen adsorption-desorption) was used. 2 / g, pore volume 0.05cm 3 / g; Y2O3 molar content is 4.5 mol.%, with a tetragonal phase structure). All other conditions are the same.

[0187] 0.5525 g of Ni(NO3)2·6H2O and 150 ml of deionized water were placed in a beaker and stirred thoroughly at 25 °C for 5 h to dissolve and obtain a mixed solution. 1.00 g of YSZ support was added to the solution and stirred for 5 h to mix evenly. The suspension was poured into a flask and placed in a rotary evaporator at 70 °C under vacuum for rotary evaporation. The solid obtained after rotary evaporation was scraped off the inner wall of the flask and placed in a crucible, then placed in a constant temperature drying oven at 90 °C for 12 h to dry thoroughly. N2 was introduced into a tube furnace and the temperature was increased to 700 °C at a rate of 5 °C / min. The gas was then switched to a 10 vol.% H2 / Ar mixture, and the catalyst was reduced for 5 h.

[0188] Ni / YSZ, a catalyst supported on an active metal, was obtained.

[0189] The Ni content is 10.07 wt.%, and the YSZ content is 89.93 wt.%. The particle size of the Ni metal species on the YSZ support surface is 30-60 nm.

[0190] The evaluation conditions for the methane dry reforming reaction were the same as those in Example 1.

[0191] Comparative Example 2

[0192] Prepared according to the method of Example 1, except that Ag is not introduced; conventional YSZ (specific surface area of ​​5 m² determined by nitrogen adsorption-desorption) was used. 2 / g, pore volume 0.05cm 3 / g; Y2O3 molar content is 4.5 mol.%, with a tetragonal phase structure). All other conditions are the same.

[0193] 0.3114 g of Co(CH3COO)2·4H2O and 150 ml of deionized water were placed in a beaker and stirred thoroughly at 25 °C for 5 h to dissolve and obtain a mixed solution. 1.00 g of YSZ support was added to this solution and stirred for 5 h to mix evenly. The suspension was poured into a flask and placed in a rotary evaporator at 70 °C under vacuum for rotary evaporation. The solid obtained after rotary evaporation was scraped off the inner wall of a flask and placed in a crucible. It was then placed in a constant temperature drying oven at 90 °C for 12 h to dry thoroughly. N2 was introduced into a tube furnace and the temperature was increased to 700 °C at a rate of 5 °C / min. The gas was then switched to a 10 vol.% H2 / Ar mixture, and the catalyst was reduced for 5 h.

[0194] The Co / YSZ catalyst supported on an active metal catalyst was obtained, wherein,

[0195] The content of Co is 7.38 wt.%, and the content of YSZ is 92.62 wt.%. The particle size of the Co metal species on the surface of the YSZ carrier is 30-60 nm.

[0196] The evaluation conditions for the methane dry reforming reaction were the same as those in Example 1.

[0197] Table 1

[0198]

[0199]

[0200]

[0201] Figure 1These are energy-dispersive X-ray spectroscopy (EDS-mapping) images of the catalyst in Example 1 obtained by scanning electron microscopy (SEM).

[0202] Figure 2 This is an energy-dispersive X-ray spectroscopy (EDS-mapping) image of the catalyst in Comparative Example 2 using a scanning electron microscope (SEM).

[0203] Combination Figure 1 , 2 The comparison shows that with the addition of Ag additives, the metal dispersion on the carrier surface is improved, and the active metals are evenly distributed on the carrier surface.

[0204] Figure 3 The X-ray diffraction (XRD) patterns of the catalysts in Examples 1-5 and Comparative Examples 1-2 after 150 h of high-pressure reaction in methane dry reforming are shown.

[0205] Figure 4 Thermogravimetric analysis (TGA) curves of the catalysts in Examples 1-5 and Comparative Examples 1-2 after 150 h of high-pressure reaction in methane dry reforming.

[0206] Table 1 shows the catalytic reaction performance data of Examples 1-8 and Comparative Examples 1-2 at 20 bar, including methane conversion rate, carbon dioxide conversion rate, activity decrease rate, and catalyst carbon deposition after 150 h of reaction. The carbon dioxide conversion rate is higher than the methane conversion rate because the presence of the reverse water-gas shift side reaction also consumes some carbon dioxide.

[0207] The stability evaluation results of the catalysts are shown in Table 1. The table shows that under high temperature and high pressure conditions, the catalysts in Examples 1, 2, 3, 4, and 5 exhibited relatively stable performance and slow deactivation rates. In contrast, Comparative Examples 1 and 2 showed faster deactivation rates and poorer reaction stability under high pressure conditions. The varying amounts of active metal and promoter Ag resulted in different catalytic activities. The lower specific surface area of ​​the YSZ support in Examples 6 and 7, and the excessively high amount of promoter Ag in Example 8, both led to reduced catalyst activity, although their deactivation rates and carbon deposition remained relatively low.

[0208] To understand the surface composition, structural changes, and carbon deposition of the catalyst after the reaction, XRD diffraction analysis was performed on the catalyst. (See attached image.) Figure 3The diffraction patterns show that the catalyst in the examples retains the YSZ support structure after the reaction, with no observed carbon deposition peaks. In contrast, Comparative Examples 1 and 2 show significant carbon deposition peaks (at approximately 27° 2θ). Carbon deposition is the cause of catalyst deactivation and decreased stability. Characterization indicates that the catalysts in the examples have significant anti-carbon deposition effects and excellent stability. However, the XRD pattern of the catalyst after the reaction can only determine whether graphitic carbon deposits are present, not the amount of carbon deposition. Therefore, thermogravimetric analysis (TGA) was used to determine the amount of carbon deposition in the catalyst. (See below) Figure 4 See Table 1. During the TGA test, the reacted catalyst was heated from room temperature to 850°C in air at a heating rate of 10°C / min. Figure 4 The TG results after the catalyst reaction show that the catalyst in the examples has less carbon deposition, less than 10% of its own weight, while the comparative examples 1 and 2 have more carbon deposition, even exceeding 50% of their own weight. In summary, although the addition of Ag promoter reduces catalytic activity to some extent, it significantly reduces the catalyst deactivation rate and the amount of carbon deposition. This is presumably because the addition of Ag promoter covers the low-coordination active sites on the active metal surface, making it difficult for carbon deposits to nucleate and grow, forming graphitic carbon deposits; simultaneously, Ag also reduces the carbon formation rate and lowers the surface carbon concentration.

[0209] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A silver-containing catalyst characterized in that, The catalyst comprises a YSZ carrier and an active component supported on the YSZ carrier, the active component elements comprising a metal element M and Ag, the metal element M being selected from Group VIII elements.

2. The catalyst of claim 1, wherein, In the silver-containing catalyst, M is selected from one or more of Co, Ni, Rh, Ir, Pd, Pt, Ru, preferably Co and / or Ni; and / or The metal element M and Ag do not form an alloy after being subjected to a reduction treatment with metal species in the YSZ carrier, and the reduced M and Ag exist in the form of metal elements; and / or The content of M is 0.1-8 wt.%, the content of Ag is 0.5-20 wt.%, and the content of the YSZ carrier is 70-99 wt.%, based on the total weight of the catalyst; and / or The mass ratio of Ag to M is (0.2-20):1; and / or The specific surface area of the support is between 10 and 150 m2 / g, preferably between 30 and 100 m2 / g 2 The specific surface area of the support is between 10 and 150 m2 / g, preferably between 30 and 100 m2 / g 2 The specific surface area of the support is Pore volume 0.05-0.40 cm3 / g; and / or 3 / g; and / or The particle size of the reduced metal species of the active component comprising Ag and M on the catalyst carrier is in the nanometer range; preferably, the particle size is 1-100 nm; and / or In the YSZ carrier, the molar content of yttrium oxide is 2-10 mol.%, preferably 4-8 mol.%; and / or The YSZ carrier is in a tetragonal phase structure.

3. A process for the preparation of a silver-containing catalyst, characterized in that, The method comprises: contacting a solution of an M-containing compound and an Ag-containing compound with a YSZ carrier for impregnation; drying and reduction roasting the obtained solid; Preferably, The specific surface area of the YSZ support is 10-150 m 2 / g, preferably 30-100 m 2 / g; and / or The pore volume of the YSZ support is 0.05-0.40 cm3 / g 3 / g; and / or The molar percentage content of yttrium oxide in the YSZ carrier is 2-10 mol.%, preferably 4-8 mol.%; and / or The YSZ carrier is in a tetragonal phase structure.

4. The production method according to claim 3, wherein The preparation method of the YSZ carrier comprises: mixing a Zr source, a Y source and a strong cation polyelectrolyte in the presence of an alkaline substance to form an alkaline solution, and then performing a hydrothermal precipitation reaction, drying and calcining the obtained solid to obtain the YSZ carrier; Preferably, The number average molecular weight of the strong cation polyelectrolyte is 1-12 million; and / or The strong cation polyelectrolyte is a cationic polymer with amine groups, imine groups, tertiary amine groups or quaternary ammonium salt groups in the repeating units; more preferably, the strong cation polyelectrolyte is selected from one or more of poly diallyl dimethyl ammonium chloride, poly methacryloyloxyethyl trimethyl ammonium chloride, poly hexamethylene biguanide bromide, cationic polyacrylamide, polyhydroxyethyl cellulose ether quaternary ammonium salt, polyethyleneimine and its hydrochloride, and polyvinylpyridine; and / or The weight ratio of the total amount of Zr and Y elements in the solution to the strong cation polyelectrolyte is 1:(0.1-6); and / or The Zr source is selected from one or more of ZrO(NO3)2 and ZrOCl2·8H2O; and / or The Y source is selected from one or more of Y(CH3COO)3·4H2O, Y(NO3)3·6H2O and YCl3·6H2O; and / or The molar ratio of the Zr source to the Y source is 1:(0.04-0.5); And / or The alkaline substance is selected from one or more of urea, ammonia, sodium carbonate, sodium bicarbonate, sodium hydroxide and potassium hydroxide; And / or Deionized water is used as the solvent, and the concentration of the Zr source in the solution is 0.02-6.5 mol / L; Preferably, The conditions of the hydrothermal reaction comprise: The temperature is 130-160℃, and / or the time is 10-15h; And / or The drying conditions include: The drying temperature is 60-100℃, and / or the time is 3-24h; and / or The calcination conditions include: The calcination temperature is 600-1200℃, and / or the time is 3-8h.

5. The production process according to claim 3 or 4, wherein, The conditions of the contact impregnation include: The amount of the M compound, the Ag compound and the YSZ carrier is such that the content of M is 0.1-8wt.%, the content of Ag is 0.5-20wt.% and the content of YSZ carrier is 70-99wt.% based on the total weight of the catalyst; Preferably, the mass ratio of Ag to M is (0.2-20):1; and / or The contact impregnation is performed by co-impregnation; and / or The operation conditions of drying and reduction calcination of the obtained solid include: The drying temperature is 60-100℃, and the drying time is 3-24h; and / or The reduction calcination is performed in a hydrogen-containing atmosphere, which is a hydrogen-containing atmosphere diluted by an inert gas, wherein the hydrogen content is 1vol.%-99vol.%; The operation conditions of reduction include: the heating rate is 1-5℃ / min, the final temperature is 600-900℃, and the holding time at the final temperature is 3-8h.

6. The silver-containing catalyst prepared by the method of any one of claims 3-5.

7. The use of the catalyst of any one of claims 1-2, 6 in the reforming of methane, preferably in dry reforming of methane, steam reforming of methane, combined reforming of methane.

8. A process for the dry reforming of methane, characterized in that, The method includes: contacting methane and carbon dioxide in the presence of the catalyst of any one of claims 1-2, 6.

9. The method of claim 8, wherein, The conditions of the contact reaction include: The pressure is 2-40bar; and / or The temperature is 700-900℃; and / or The molar ratio of methane to carbon dioxide is 1:(0.5-2); and / or Gas space velocity is 2000-90000 mL-h -1 ·g cat -1 , preferably 3000-10000 mL-h -1 ·g cat -1 .

10. The method of claim 8 or 9, wherein The contact reaction is performed in the presence of a diluent selected from one or more of SiC, SiO2; more preferably, the mass ratio of the diluent to the catalyst is 0.5-4.

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