Metal oxide nano island modified nickel-based catalyst for low-temperature CO2 methanation as well as preparation method and application of metal oxide nano island modified nickel-based catalyst

Abstract

The invention discloses a metal oxide nano island modified nickel-based catalyst for low-temperature CO2 methanation as well as a preparation method and application of the metal oxide nano island modified nickel-based catalyst, and belongs to the technical field of preparation of low-temperature CO2 methanation catalysts. The catalyst comprises a metal nickel salt and a metal oxide nano island, the particle size of the metal nickel salt is 5-20 nm, and the particle size of the metal oxide nano island is 2-10 nm. The invention further discloses a preparation method and application of the metal oxide nano island modified nickel-based catalyst for low-temperature CO2 methanation. According to the novel catalyst, CO2 can be converted into CH4 under the mild conditions of 160 DEG C and 0.1 MPa, the CO2 conversion rate is close to 90% at 220 DEG C, the CH4 selectivity is 100%, and the reaction temperature is reduced by 100 DEG C compared with that of a traditional nickel-based catalyst.

Description

Technical Field

[0001] The present invention belongs to CO 2 The technical field of methanation catalyst preparation is particularly related to a method for preparing a low-temperature CO 2 Metal oxide nano-island modified nickel-based catalyst for methanation, preparation method and application thereof. Background Art

[0002] As an important primary energy source and raw material, CH 4 The huge demand and uneven distribution in the world make it difficult to develop new CH 4 Production process is very necessary. 2 Methanation reaction is also called Sabatier reaction. It is a large-scale synthesis of CH 4 and recycling CO 2 Provides an effective way. 4 With H 2 Compared with other materials, CH has great advantages in storage and transportation. 4 It has become an important energy storage carrier in the concept of power-to-gas. 2 Methanation reaction can provide necessary guarantee for daily water and fuel needs in human exploration of the universe. 2 Methanation reaction has high conversion rate, high selectivity and wide operating range. As energy and environmental issues on the earth become increasingly prominent, the demand for this process will increase significantly. Therefore, it is urgent to develop highly active and highly selective CO 2 Methanation catalyst.

[0003] Currently, metal catalysts (Ru, Rh, Pd, Fe, Co, Ni, etc.) have been used for CO 2 Methanation reaction. Among them, nickel-based catalysts show great application potential due to their low cost and high activity. However, the reaction temperature of traditional nickel-based catalysts is high (300-400°C), with high energy consumption and poor catalyst stability. Improving the low-temperature activity and operating stability of nickel-based catalysts is of great significance for practical applications. Tail gas from coal-fired power plants and steel mills is an important CO 2 The exhaust gas temperature is usually between 150 and 300°C. 2 Methanation reaction will further increase CO 2 Therefore, it is necessary to develop nickel-based methanation catalysts suitable for mild conditions. 2 The size effect, structural sensitivity and strong metal-support interaction that are common in methanation catalysts are well understood, but the ability to achieve CO under mild conditions, especially at around 200 °C and 0.1 MPa, is still a challenge. 2The development of highly active nickel-based catalysts for methanation has been slow. Conventional metal oxide-supported nickel-based catalysts emphasize CO bond activation over CO 2 The role of hydrogenation in the methanation reaction is neglected, so the effect of CO bond activation and H 2 The activation fails to achieve a good match in kinetics, which may be the key reason why it is difficult to achieve a major breakthrough in catalytic performance.

[0004] In view of this, in order to overcome the shortcomings of the prior art, it is necessary to provide a method for 2 Metal oxide nano-islands modified nickel-based catalysts for methanogenication to achieve high conversion, high selectivity, and high stability of CO under mild conditions 2 Methanation process. Summary of the invention

[0005] The object of the present invention is to provide a method for low temperature CO 2 The metal oxide nano-island modified nickel-based catalyst for methanation has a simple preparation process and low cost, and can achieve high conversion rate, high selectivity and high stability of CO under mild conditions. 2 Methanation process.

[0006] One of the purposes of the present invention is to provide a method for 2 Metal oxide nanoislands modified nickel-based catalysts for methanogenesis.

[0007] The technical solution of the present invention to solve the above technical problems is: a method for low temperature CO 2 The methanogenic metal oxide nano-island modified nickel-based catalyst comprises a metal nickel salt and a metal oxide nano-island, wherein the particle size of the metal nickel salt is 5-20 nm, the particle size of the metal oxide nano-island is 2-10 nm, and the metal oxide in the metal oxide nano-island is selected from one of aluminum oxide, cerium oxide, zirconium oxide, yttrium oxide, scandium oxide, zinc oxide, gallium oxide or cadmium oxide.

[0008] The present invention is used for low temperature CO 2 The principle of metal oxide nano-islands modified nickel-based catalysts for methanation is:

[0009] The surface of the metal oxide nano-island is the CO bond activation site. The smaller the size of the metal oxide nano-island, the more active the surface oxygen species are, and it is easier to generate oxygen vacancies to participate in the CO bond dissociation. The metal nickel salt provides abundant H 2 Activation site, CO 2 It is very easy to activate on the metal oxide nano-islands and combine with the active hydrogen species on the surface of the surrounding metal nickel salts, and then undergo subsequent hydrogenation reactions to obtain CH 4Highly dispersed nickel species can provide a hydrogen-rich atmosphere, which is conducive to deep hydrogenation reactions. The oxide nano-island-metal nickel interface serves as a low-temperature CO 2 The methanation reaction site can provide a hydrogen-rich atmosphere while promoting CO bond dissociation, thereby achieving rate matching between CO bond dissociation and hydrogenation reaction.

[0010] The catalytic performance results show that the catalyst provided by the present invention can convert CO to 2 Convert to CH 4 , CO at 220℃ 2 The conversion rate is close to 90%, CH 4 The selectivity is 100%, and the reaction temperature is reduced by 100° C. compared with the traditional nickel-based catalyst. In addition, the catalyst provided by the present invention maintains excellent stability during a long-term operation of 125 hours, and has great application potential.

[0011] The present invention is used for low temperature CO 2 The beneficial effects of metal oxide nano-islands modified nickel-based catalysts for methanation are:

[0012] 1. The present invention achieves the synergistic and efficient CO bond dissociation and hydrogenation reaction by constructing a metal oxide nano-island-metal nickel active interface. The metal oxide nano-island modified nickel-based catalyst can achieve high CO under mild conditions of 220°C and 0.1MPa. 2 Conversion rate, high CH 4 Selective and highly stable catalytic CO 2 Methanation reaction, under high space velocity conditions CO 2 The conversion rate is greater than 80% and the methane selectivity is greater than 99%, while most current catalysts require temperatures above 300°C to achieve high methanogenic activity.

[0013] 2. The metal oxide nano-island modified nickel-based catalyst provided by the present invention further improves its catalytic activity by adjusting the content of metal oxide and metallic nickel and precisely controlling the microstructure and reaction interface of the metal oxide nano-island and metallic nickel.

[0014] Based on the above technical solution, the present invention can also be improved as follows.

[0015] Furthermore, the mass content of the metal nickel salt is 50-95wt%, and the mass content of the metal oxide nano-islands is 5-50wt%.

[0016] Furthermore, the low temperature CO 2 The particle size of the metal oxide nano-island modified nickel-based catalyst for methanation is 10-200 meshes.

[0017] The second object of the present invention is to provide a method for low temperature CO 2 Preparation method of metal oxide nano-islands modified nickel-based catalyst for methanation.

[0018] The technical solution of the present invention to solve the above technical problems is: a method for low temperature CO 2 The preparation method of the metal oxide nano-island modified nickel-based catalyst for methanation comprises the following steps:

[0019] S1: dissolving a metal nickel salt and a precursor salt of a metal oxide in a solvent to obtain a solution A;

[0020] S2: dissolving oxalic acid dihydrate in a solvent to obtain solution B;

[0021] S3: adding solution B to solution A and stirring at room temperature, then collecting the solid product, washing it with ethanol for 2-4 times, drying it, and finally calcining it in a muffle furnace at 300-600° C. for 1-10 h to obtain a catalyst precursor;

[0022] S4: The catalyst precursor obtained in S3 is reduced under normal pressure in a hydrogen atmosphere to obtain 2 Metal oxide nanoislands modified nickel-based catalysts for methanogenesis.

[0023] The present invention is used for low temperature CO 2 The beneficial effects of the preparation method of the metal oxide nano-island modified nickel-based catalyst for methanation are:

[0024] The present invention adopts a one-step co-precipitation combined with hydrogen reduction method for preparation, which has the advantages of simple preparation process and easy scale-up; wherein dihydrated oxalic acid is selected as a precipitant in the co-precipitation method, and dihydrated oxalic acid can efficiently complex metal cations, which is beneficial to the dispersion of various components in the catalyst.

[0025] Based on the above technical solution, the present invention can also be improved as follows.

[0026] Further, the metal nickel salt in step S1 is selected from one of nickel nitrate hexahydrate, nickel chloride hexahydrate or nickel sulfate hexahydrate; the precursor salt of the metal oxide is selected from one of aluminum nitrate nonahydrate, cerium nitrate hexahydrate, zirconium nitrate pentahydrate, yttrium nitrate hexahydrate, hydrated scandium nitrate, zinc nitrate hexahydrate, hydrated gallium nitrate, samarium nitrate hexahydrate, cadmium nitrate tetrahydrate, aluminum chloride, cerium chloride, zirconium chloride, zirconium oxychloride, yttrium chloride, scandium chloride, zinc chloride, gallium chloride, samarium chloride, cadmium chloride, aluminum sulfate 18hydrate, hydrated ammonium cerium sulfate, zirconium sulfate tetrahydrate, yttrium sulfate octahydrate or zinc sulfate heptahydrate.

[0027] Furthermore, the amount of the metal nickel salt is 0.01-0.02 mol, the amount of the metal oxide precursor salt is 0.01-0.02 mol; and the amount of the oxalic acid dihydrate in step S2 is 0.04-0.06 mol.

[0028] The above further beneficial effects are: oxalic acid dihydrate can efficiently complex metal cations, which is beneficial to the dispersion of various components in the catalyst, and the obtained catalyst has a large specific surface area and good dispersibility.

[0029] Furthermore, in step S1 and step S2, the solvent is deionized water or ethanol; the amount used is 80-120 mL.

[0030] Furthermore, in step S4, the reduction pretreatment hydrogen concentration is 5-100%, and the total flow rate is 5-50 mL / min; the reduction heat treatment temperature is 350-600° C., and the heat treatment time is 4-10 h.

[0031] The third object of the present invention is to provide a method for low temperature CO 2 Application of Metal Oxide Nano-islands Modified Nickel-based Catalysts for Methanation.

[0032] The technical solution of the present invention to solve the above technical problems is: the above-mentioned low temperature CO 2 Metal oxide nano-islands modified nickel-based catalysts for methanogenesis in low-temperature CO 2 Application in methanation reactions.

[0033] The beneficial effects of the application of the present invention are:

[0034] The present invention is used for low temperature CO 2 The metal oxide nano-islands modified nickel-based catalyst for methanogenesis maintained excellent stability during long-term operation of 125 h and has great application potential.

[0035] Based on the above technical solution, the present invention can also be improved as follows.

[0036] Furthermore, the specific method of the application is: using the low temperature CO 2 The metal oxide nano-islands modified nickel-based catalyst for methanation was placed in a fixed bed reactor, and a mixed reaction gas with a molar ratio of carbon dioxide to hydrogen of 1:4 was introduced at a mass space velocity of 6000-27000 mL g -1 h -1 , reaction pressure 0.1-1.0MPa, reaction temperature 160-340℃. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 TEM structure diagram of nickel-based catalyst modified with metal oxide nanoislands.

[0038] Figure 2 Effect of metal loading on catalytic performance of nickel-based catalysts modified with metal oxide nanoislands.

[0039] Figure 3 Comparison of the performance of metal oxide nano-islands modified nickel-based catalysts and reported catalysts.

[0040] Figure 4 To investigate the influence of preparation method on catalytic performance of nickel-based catalysts modified with metal oxide nano-islands.

[0041] Figure 5 XRD spectra of metal oxide nano-islands modified nickel-based catalysts obtained by different preparation methods.

[0042] Figure 6 The catalytic performance of nickel-based catalysts modified with metal oxide nano-islands at different mass space velocities.

[0043] Figure 7 125-hour CO degradation for metal oxide nano-islands modified nickel-based catalysts 2 Catalytic performance of methanation reaction.

[0044] Figure 8 The effect of the type of metal oxide nanoisland precursor on the catalytic performance.

[0045] Fig. 9 Example 1 and Comparative Example 1CO 2 Comparison of apparent activation energies of methanation reactions.

[0046] Fig.10 Example 1 and Comparative Example 1CO 2 Methanation CO 2 and H 2 Comparison of reaction orders.

[0047] Fig.11 Example 1 and Comparative Example 1CO 2 and H 2 Comparison of adsorption performance.

[0048] Fig.12 XPS results of Example 1 and Comparative Example 1 after different treatments. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the present invention more clear, the following Figure 1-9The present invention is further described in detail with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0050] Additional aspects and advantages of the present invention will be given in part in the following description, and will become apparent from the following description, or learned through the practice of the present invention. It should be understood that the following description is only used to explain the present invention and is not intended to limit the present invention.

[0051] As used herein, the terms "comprises," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.

[0052] The phrase "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0053] When dosage, concentration, or other value or parameter is expressed as a range, preferred range, or a range limited by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when disclosing a range of "1 to 5", the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0054] In some examples, approximate terms may correspond to the instrumental precision of the measured value. In the present specification and claims, range limits may be combined and / or interchanged. If not otherwise specified, these ranges include all sub-ranges contained therein.

[0055] The indefinite articles "a" and "an" before the elements or components of the present invention have no restrictions on the number of elements or components (i.e. the number of occurrences). Therefore, "a" or "an" should be interpreted as including one or at least one, and the elements or components in the singular form also include the plural form, unless the quantity obviously refers to the singular form only.

[0056] The terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" described in the present invention mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0057] Unless otherwise specified, the raw materials and equipment used in the present invention can be purchased from the market or are commonly used in the art. The methods in the embodiments, unless otherwise specified, are all conventional methods in the art.

[0058] In some embodiments, the present invention provides a method for low temperature CO 2 A metal oxide nano-island modified nickel-based catalyst for methanation, characterized in that it comprises a metal nickel salt and a metal oxide nano-island, wherein the particle size of the metal nickel salt is 5-20 nm, the particle size of the metal oxide nano-island is 2-10 nm, and the metal oxide in the metal oxide nano-island is selected from one of aluminum oxide, cerium oxide, zirconium oxide, yttrium oxide, scandium oxide, zinc oxide, gallium oxide or cadmium oxide. Further, the particle size of the metal nickel salt can be 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm or 20 nm, and the particle size of the metal oxide nano-island can be 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm.

[0059] In some embodiments, the mass content of the metal nickel salt is 50-95wt%, and the mass content of the metal oxide nano-islands is 5-50wt%. Further, the mass content of the metal nickel salt can be one of 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%; further, the mass content of the metal oxide can be one of 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%.

[0060] In some embodiments, the low temperature CO 2The particle size of the metal oxide nano-islands modified nickel-based catalyst for methanation is 10-200 mesh. Further, the particle size of the catalyst can be 10 mesh, 20 mesh, 30 mesh, 40 mesh, 50 mesh, 60 mesh, 70 mesh, 80 mesh, 90 mesh, 100 mesh, 110 mesh, 120 mesh, 130 mesh, 140 mesh, 150 mesh, 160 mesh, 170 mesh, 180 mesh, 190 mesh or 200 mesh.

[0061] In some embodiments, the present invention provides a method for low temperature CO 2 The preparation method of the metal oxide nano-island modified nickel-based catalyst for methanation comprises the following steps:

[0062] S1: dissolving a metal nickel salt and a precursor salt of a metal oxide in a solvent to obtain a solution A;

[0063] S2: dissolving oxalic acid dihydrate in a solvent to obtain solution B;

[0064] S3: adding solution B to solution A and stirring at room temperature, then collecting the solid product, washing it with ethanol for 2-4 times, drying it, and finally calcining it in a muffle furnace at 300-600° C. for 1-10 h to obtain a catalyst precursor;

[0065] S4: The catalyst precursor obtained in S3 is reduced under normal pressure in a hydrogen atmosphere to obtain 2 Metal oxide nanoislands modified nickel-based catalysts for methanogenesis.

[0066] Further, in some embodiments, the metal nickel salt in step S1 is selected from one of nickel nitrate hexahydrate, nickel chloride hexahydrate or nickel sulfate hexahydrate; the precursor salt of the metal oxide is selected from one of aluminum nitrate nonahydrate, cerium nitrate hexahydrate, zirconium nitrate pentahydrate, yttrium nitrate hexahydrate, scandium nitrate hydrate, zinc nitrate hexahydrate, gallium nitrate hydrate, samarium nitrate hexahydrate, cadmium nitrate tetrahydrate, aluminum chloride, cerium chloride, zirconium chloride, zirconium oxychloride, yttrium chloride, scandium chloride, zinc chloride, gallium chloride, samarium chloride, cadmium chloride, aluminum sulfate 18hydrate, cerium ammonium sulfate hydrate, zirconium sulfate tetrahydrate, yttrium sulfate octahydrate or zinc sulfate heptahydrate.

[0067] Furthermore, in step S1, the amount of the metal nickel salt is 0.01-0.02 mol, and the amount of the metal oxide precursor salt is 0.01-0.02 mol; and in step S2, the amount of oxalic acid dihydrate is 0.04-0.06 mol.

[0068] Furthermore, the molar ratio of the metal nickel salt to the metal oxide is 4-9:1.

[0069] Furthermore, in step S1 and step S2, the solvent is deionized water or ethanol; the amount used is 80-120 mL.

[0070] Furthermore, in step S4, the reduction pretreatment hydrogen concentration is 5-100%, and the total flow rate is 5-50 mL / min; the reduction heat treatment temperature is 350-600° C., and the heat treatment time is 4-10 h.

[0071] In some embodiments, the present invention provides the above-mentioned low temperature CO 2 Metal oxide nano-islands modified nickel-based catalysts for methanogenesis in low-temperature CO 2 Application in methanation reactions.

[0072] Furthermore, the application method is: using the low temperature CO 2 The metal oxide nano-islands modified nickel-based catalyst for methanation was placed in a fixed bed reactor, and a mixed reaction gas with a molar ratio of carbon dioxide to hydrogen of 1:4 was introduced at a mass space velocity of 6000-27000 mL g -1 h -1 , reaction pressure 0.1-1.0MPa, reaction temperature 160-340℃.

[0073] The following is a further description with reference to specific embodiments.

[0074] Example 1

[0075] 1. Dissolve 5.23 g of nickel nitrate hexahydrate and 0.77 g of yttrium nitrate hexahydrate in 100 mL of ethanol to obtain solution A;

[0076] 2. Dissolve 6.31 g of oxalic acid dihydrate in 100 mL of ethanol to obtain solution B;

[0077] 3. Add solution B to solution A, stir at room temperature for 4 hours, collect the solid product, wash it with ethanol three times, dry it at 80°C for 12 hours, and then calcine it in a muffle furnace at 400°C for 2 hours to obtain a catalyst precursor;

[0078] 4. The catalyst precursor obtained in step 3 was pre-treated under a hydrogen atmosphere at 500°C and normal pressure for 5 hours to obtain a catalyst for low-temperature CO 2 Metal oxide nano-islands modified nickel-based catalyst for methanogenesis, named Y 2 O 3 / Ni catalyst.

[0079] The catalyst was granulated into 40-80 meshes and placed in a fixed bed for CO 2 Methanation reaction. CO is introduced 2 and H 2The molar ratio of the mixed reaction gas is 1:4, and the space velocity is 15000-27000mL g -1 h -1 , the reaction pressure is 0.1MPa, and the reaction temperature is 160-280℃.

[0080] Example 2

[0081] The difference from Example 1 is that in step 1, 4.65 g of nickel nitrate hexahydrate and 1.53 g of yttrium nitrate hexahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0082] The catalyst obtained in this example is named Y 2 O 3 / Ni-2 catalyst.

[0083] Example 3

[0084] The difference from Example 1 is that in step 1, 5.52 g of nickel nitrate hexahydrate and 0.38 g of yttrium nitrate hexahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0085] The catalyst obtained in this example is named Y 2 O 3 / Ni-3 catalyst.

[0086] Example 4

[0087] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.86 g of zirconium nitrate pentahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0088] The catalyst obtained in this example is named ZrO 2 / Ni catalyst.

[0089] Example 5

[0090] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.87 g of cerium nitrate hexahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0091] The catalyst obtained in this example is named CeO 2 / Ni catalyst.

[0092] Example 6

[0093] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.75 g of aluminum nitrate nonahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0094] The catalyst obtained in this example is named Al 2 O 3 / Ni catalyst.

[0095] Example 6

[0096] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.75 g of aluminum nitrate nonahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0097] The catalyst obtained in this example is named Al 2 O 3 / Ni catalyst.

[0098] Example 7

[0099] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.80 g of chromium nitrate nonahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0100] The catalyst obtained in this example is named Cr 2 O 3 / Ni catalyst.

[0101] Example 8

[0102] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.87 g of lanthanum nitrate hexahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0103] The catalyst obtained in this example is named La 2 O 3 / Ni catalyst.

[0104] Example 9

[0105] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.50 g of manganese nitrate tetrahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0106] The catalyst obtained in this example is named as MnO / Ni catalyst.

[0107] Example 10

[0108] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.51 g of magnesium nitrate hexahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0109] The catalyst obtained in this example is named MgO / Ni catalyst.

[0110] Embodiment 11

[0111] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.47 g of calcium nitrate tetrahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0112] The catalyst obtained in this example is named CaO / Ni catalyst.

[0113] Example 12

[0114] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.52 g of scandium nitrate hydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0115] The catalyst obtained in this example is named Sc 2 O 3 / Ni catalyst.

[0116] Example 13

[0117] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.89 g of samarium nitrate hexahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0118] The catalyst obtained in this example is named Sm 2 O 3 / Ni catalyst.

[0119] Embodiment 14

[0120] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.87 g of praseodymium nitrate hexahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0121] The catalyst obtained in this example is named Pr 6 O 11 / Ni catalyst.

[0122] Embodiment 15

[0123] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.88 g of neodymium nitrate hydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0124] The catalyst obtained in this example is named Nd 2 O 3 / Ni catalyst.

[0125] Example 16

[0126] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.23 g of ammonium metavanadate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0127] The catalyst obtained in this example is named V 3 O 5 / Ni catalyst.

[0128] Embodiment 17

[0129] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.88 g of ammonium metavanadate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0130] The catalyst obtained in this example is named WO 3 / Ni catalyst.

[0131] Embodiment 18

[0132] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.40 g of manganese chloride tetrahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0133] The catalyst obtained in this example is named as MnO-Cl / Ni catalyst.

[0134] Embodiment 19

[0135] The difference from Example 1 is that in step 1, 5.23 g of nickel nitrate hexahydrate and 0.22 g of anhydrous calcium chloride are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0136] The catalyst obtained in this example is named CaO-Cl / Ni catalyst.

[0137] Comparative Example 1

[0138] The difference from Example 1 is that in step 1, 0.58 g of nickel nitrate hexahydrate and 6.13 g of yttrium nitrate hexahydrate are dissolved in 100 mL of ethanol to obtain solution A. The rest are the same.

[0139] The catalyst obtained in this comparative example is named Ni / Y 2 O 3 catalyst.

[0140] Comparative Example 2

[0141] The difference from Example 1 is that in step 1, 5.82 g of nickel nitrate hexahydrate is dissolved in 100 mL of ethanol to obtain solution A. The rest is the same.

[0142] The catalyst obtained in this comparative example is named NiO catalyst.

[0143] Comparative Example 3

[0144] The difference from Example 1 is that in step 1, 5.82 g of nickel nitrate hexahydrate is dissolved in 100 mL of ethanol to obtain solution A; in step 3, solution B is added to solution A, stirred at room temperature for 4 h, then the solid product is collected, washed with ethanol 3 times, dried at 80° C. for 12 h, and then placed in a muffle furnace for calcination at 400° C. for 2 h to obtain nickel oxide; in step 4, 0.5696 g of yttrium nitrate nonahydrate is dissolved in 5 mL of deionized water, gradually added dropwise to 1 g of nickel oxide obtained in step 3, stirred at room temperature for 24 h, dried at 110° C. for 12 h, and calcined at 400° C. for 2 h. The rest are the same.

[0145] The catalyst obtained in this comparative example is named Y 2 O 3 / Ni-IM catalyst.

[0146] Table 1 Catalysts for low temperature CO 2 CO from methanation reaction 2 Conversion rate and CH 4 Selectivity

[0147]

[0148] Table 1 shows the performance of each catalyst for CO 2 Methanation reaction of CO at 220°C 2 Conversion rate and CH 4 Selectivity. Comparing Examples 1-3 with Comparative Examples 1-3, it was found that Y 2 O 3 Nano-island modified nickel catalyst (Y 2 O 3 / Ni) has the best low temperature CO 2 Methanogenic activity, up to 80% CO at 220°C 2 conversion and 100% methane selectivity. Figure 1 Transmission electron microscopy images show that Y 2 O 3 Compared with traditional supported catalysts, Ni has a unique structure, with small particles of Y evenly distributed on the surface of active metal nickel. 2 O 3 Nano-islands, metal oxide nano-islands play a role in stabilizing and dispersing nickel. 2 O 3 / Ni as an example, the size of metal nickel remains at 15nm, on the other hand, it can effectively activate the CO bond and accelerate the CO 2Based on this novel structure, the catalyst surface has abundant CO bond activation and H 2 The activation site can achieve the kinetic matching of CO dissociation and hydrogenation reaction, thus realizing low-temperature CO 2 Methanation.

[0149] Comparing Example 1 with Example 4-17, it is found that Y 2 O 3 / Ni、ZrO 2 / Ni、CeO 2 / Ni、Al 2 O 3 / Ni and Sc 2 O 3 All five catalysts showed excellent low-temperature CO 2 Methanation activity, CO 2 The conversion rates were 80.1%, 85.8%, 84.7%, 88.7% and 86.9% respectively, and the methane selectivity was 100%. The above results reflect the unique superiority of the metal oxide nano-island modified nickel-based catalyst in the present invention and the structure of the catalyst in low temperature CO 2 Universality in methanogenesis.

[0150] Figure 2 Examples 1-3 with different metal loadings of Y 2 O 3 Comparison of the reaction results of the nano-island modified nickel catalyst in the range of 160-280℃ shows that as the metal loading increases, the CO 2 The conversion rate-methane selectivity curve gradually shifts to the low temperature zone, indicating that increasing the metal loading is beneficial to the low temperature CO 2 Methanation reaction. In addition, the optimal Y 2 O 3 / Ni catalyst can catalyze CO at 160℃ 2 The methanogenic reaction was carried out at 220℃ and showed excellent performance at 15000mL g -1 h -1 Airspeed CO 2 The conversion rate reached 80% and the methane selectivity was 100%

[0151] Figure 3 Example 1Y is given 2 O 3 Nano-island-modified nickel catalyst and reporter catalyst CO 2 The performance comparison of methanation reaction shows that Y 2 O 3The nano-island modified nickel catalyst showed excellent performance at 220°C, which was 100°C lower than the reported nickel-based catalyst. Its performance was also better than that of the precious metal ruthenium-based catalyst, which showed that Y 2 O 3 Superior performance of nano-island modified nickel catalysts.

[0152] Figure 4 The effects of the catalyst preparation methods of Example 1 and Comparative Example 3 on the catalytic performance are given. Both the one-step coprecipitation method and the step-by-step impregnation method can obtain metal oxide nano-island modified nickel catalysts. Therefore, Comparative Example 3 can also show nearly 70% CO at 220°C. 2 The conversion rate is much better than that of traditional supported catalysts. The main difference between the two preparation methods is that the catalyst active metal nickel prepared by the one-step co-precipitation method is smaller in size and better in dispersion (see Figure 5 ), so the one-step co-precipitation method is better than the step-by-step impregnation method at low temperature CO 2 Better methanation performance.

[0153] Figure 6 Example 1 is given at 220°C, 0.1 MPa, 15000-27000 mL g -1 h -1 Low temperature CO in the airspeed range 2 Methanation performance, it can be seen that at high air speed Y 2 O 3 / Ni catalyst can still maintain more than 80% of CO 2 The conversion rate and 100% CH 4 Selective.

[0154] Figure 7 The results of Example 1 at 220°C, 0.1 MPa, 15000 mL g -1 h -1 The long-term operation stability under the condition of CO 2 The conversion rate was maintained above 80%, CH 4 The selectivity was always 100%, indicating that the catalyst was very stable.

[0155] Figure 8 The effects of the types of metal oxide nano-island precursors on the catalytic performance in Examples 9 and 18 as well as Examples 11 and 19 are given. It can be seen that both nitrate precursors and chloride precursors can be used to prepare such catalysts, and the catalyst synthesized with the nitrate precursor has better performance.

[0156] Fig. 9 Example 1 and Comparative Example 1CO are given 2 Comparison of the apparent activation energy of methanation shows that the apparent activation energy of the catalyst in Example 1 is as low as 44.3 kJ mol-1 In contrast, the apparent activation energy of the conventional nickel catalyst in Comparative Example 1 is as high as 93.0 kJ mol -1 , indicating that the new metal oxide nano-island modified nickel catalyst is beneficial to the low-temperature methanation reaction.

[0157] Fig.10 Example 1 and Comparative Example 1CO are given 2 Methanation CO 2 and H 2 Comparison of reaction orders, where CO 2 The reaction order is less than H 2 The reaction order indicates the reactant CO 2 Or the intermediate CO is too strongly adsorbed on the catalyst surface, or the surface H 2 The adsorption is too weak, which is not conducive to the reaction; the catalyst of Example 1 is compared with the comparative example 1CO 2 The reaction order increases, H 2 The decrease in the reaction order indicates that the catalyst surface H 2 Adsorption enhancement, CO 2 / CO adsorption is weakened, thus promoting CO 2 Methanation is carried out.

[0158] Fig.11 Example 1 and Comparative Example 1CO are given 2 and H 2 Comparison of adsorption performance shows that the catalyst in Example 1 weakly and moderately strongly adsorbs CO. 2 The catalyst of Comparative Example 1 strongly adsorbs CO 2 Mainly (52%); In addition, Example 1 Catalyst H 2 The adsorption capacity is twice that of the catalyst in Example 1. 2 Desorption temperature covers CO 2 Methanation reaction temperature range, while the catalyst of comparative example 1 will desorb H at above 450°C 2 The above results prove that the surface H 2 Adsorption enhancement, CO 2 The adsorption is weakened, which is conducive to the low-temperature methanation reaction.

[0159] Fig.12 The XPS results of Example 1 and Comparative Example 1 after different treatments are given. After the reduction treatment, the catalyst of Example 1 shows partially reduced Y 2 O 3-x Species, after CO 2 After methanation reaction, Y 2 O 3-x The species has been oxidized, indicating that Y 2 O 3-x Species can participate in CO2 Activation and promotion of CO bond dissociation, while no Y was observed in the catalyst of Comparative Example 1 after reduction treatment 2 O 3-x The formation of species indicates that metal oxide nano-islands can form highly active Y 2 O 3-x species, favoring CO bond dissociation.

[0160] It is easy for those skilled in the art to understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A metal oxide nano-island modified nickel-based catalyst for low-temperature CO2 methanation, characterized in that: It comprises a metal nickel salt and a metal oxide nano-island, wherein the particle size of the metal nickel salt is 5-20 nm, the particle size of the metal oxide nano-island is 2-10 nm, and the metal oxide in the metal oxide nano-island is selected from one of aluminum oxide, cerium oxide, zirconium oxide, yttrium oxide, scandium oxide, zinc oxide, gallium oxide or cadmium oxide.

2. The metal oxide nano-island modified nickel-based catalyst for low-temperature CO2 methanation according to claim 1, characterized in that: The mass content of the metal nickel salt is 50-95wt%, and the mass content of the metal oxide nano-islands is 5-50wt%.

3. A metal oxide nano-island modified nickel-based catalyst for low-temperature CO2 methanation according to claim 1 or 2, characterized in that: The particle size of the metal oxide nano-island modified nickel-based catalyst for low-temperature CO2 methanation is 10-200 meshes.

4. A method for preparing a metal oxide nano-island modified nickel-based catalyst for low-temperature CO2 methanation according to any one of claims 1 to 3, characterized in that: The steps include: S1: dissolving a metal nickel salt and a precursor salt of a metal oxide in a solvent to obtain a solution A; S2: dissolving oxalic acid dihydrate in a solvent to obtain solution B; S3: adding solution B to solution A and stirring at room temperature, then collecting the solid product, washing it with ethanol for 2-4 times, drying it, and finally calcining it in a muffle furnace at 300-600° C. for 1-10 h to obtain a catalyst precursor; S4: reducing the catalyst precursor obtained in S3 under normal pressure in a hydrogen atmosphere to obtain a metal oxide nano-island modified nickel-based catalyst for low-temperature CO2 methanation.

5. The method for preparing a metal oxide nano-island modified nickel-based catalyst for low-temperature CO2 methanation according to claim 4, characterized in that: The metal nickel salt in step S1 is selected from one of nickel nitrate hexahydrate, nickel chloride hexahydrate or nickel sulfate hexahydrate; the precursor salt of the metal oxide is selected from one of aluminum nitrate nonahydrate, cerium nitrate hexahydrate, zirconium nitrate pentahydrate, yttrium nitrate hexahydrate, scandium nitrate hydrate, zinc nitrate hexahydrate, gallium nitrate hydrate, samarium nitrate hexahydrate, cadmium nitrate tetrahydrate, aluminum chloride, cerium chloride, zirconium chloride, zirconium oxychloride, yttrium chloride, scandium chloride, zinc chloride, gallium chloride, samarium chloride, cadmium chloride, aluminum sulfate 18hydrate, cerium ammonium sulfate hydrate, zirconium sulfate tetrahydrate, yttrium sulfate octahydrate or zinc sulfate heptahydrate.

6. The method for preparing a metal oxide nano-island modified nickel-based catalyst for low-temperature CO2 methanation according to claim 4 or 5, characterized in that: In step S1, the amount of the metal nickel salt is 0.01-0.02 mol, and the amount of the metal oxide precursor salt is 0.01-0.02 mol; in step S2, the amount of oxalic acid dihydrate is 0.04-0.06 mol.

7. The method for preparing a metal oxide nano-island modified nickel-based catalyst for low-temperature CO2 methanation according to claim 4 or 5, characterized in that: In step S1 and step S2, the solvent is deionized water or ethanol; the amount used is 80-120 mL.

8. The method for preparing a metal oxide nano-island modified nickel-based catalyst for low-temperature CO2 methanation according to claim 4 or 5, characterized in that: In step S4, the reduction pretreatment hydrogen concentration is 5-100%, and the total flow rate is 5-50 mL / min; the reduction heat treatment temperature is 350-600° C., and the heat treatment time is 4-10 h.

9. Use of the metal oxide nano-island modified nickel-based catalyst for low-temperature CO2 methanation according to any one of claims 1 to 3 or the metal oxide nano-island modified nickel-based catalyst for low-temperature CO2 methanation prepared by the preparation method according to any one of claims 4 to 8 in a low-temperature CO2 methanation reaction.

10. The use according to claim 9, characterized in that: The specific method of the application is: The metal oxide nano-island modified nickel-based catalyst for low-temperature CO2 methanation was placed in a fixed bed reactor, and a mixed reaction gas with a molar ratio of carbon dioxide to hydrogen of 1:4 was introduced at a mass space velocity of 6000-27000 mL g -1 h -1 , reaction pressure 0.1-1.0MPa, reaction temperature 160-340℃.

Images