Nickel-supporting composite material and method for producing same

Abstract

The purpose of the present invention is to provide: a nickel-supporting composite material in which a nickel-based compound is supported on a porous coordination polymer, and which can be used as a methanation reaction catalyst using a porous coordination polymer which has a uniform spatial structure of pores and can selectively adsorb a large amount of gas; and a method for producing same. The present invention is a nickel-supporting composite material in which a nickel-based compound is supported on a porous coordination polymer, and is characterized in that a nickel-based compound is supported on a porous coordination polymer comprising a metal ion and an organic ligand having an imidazole skeleton.

Description

Nickel-loaded composite and method for producing the same

[0001] The present invention relates to a nickel-loaded composite and a method for producing the same, and more particularly to a nickel-loaded composite in which a nickel-based metal substance is loaded on a porous coordination polymer, and a method for producing the same.

[0002] Porous coordination polymers (PCPs), which consist of a central metal and multidentate organic ligands coordinated thereto, are also called metal-organic frameworks (MOFs), and are porous three-dimensional structures formed by integrating metal complexes consisting of a central metal and organic ligands. Unlike other porous materials such as zeolites and activated carbons, the pores of porous coordination polymers are capable of designing the pore size and the space within the pores, and many types have been reported based on the combination of metal ions and organic ligands. Porous coordination polymers have pore sizes of approximately 0.3 nm to approximately 3 nm and specific surface areas of approximately 1,000 m. ２ / g ~ approx. 2000m ２ / g to a maximum of 5000m ２ / g or more have been reported, and development has been promoted to use them as adsorbents for various components according to the various pore sizes.

[0003] It has also been studied that porous metal structures can be used as catalysts for alcohol oxidation reactions, CO oxidation reactions, etc. by supporting metal nanoparticles on the structures. For example, in the following Patent Document 1, a porous coordination polymer (PCP) is a UiO66 type PCP or a MIL53 type PCP, and the metal ions constituting the PCP are Zr ４＋ , Hf ４＋ , Al ３＋ , Ga ３＋ and In ３＋ and a composite catalyst in which copper-based fine particles are supported on PCP, the organic ligand of which is terephthalic acid or the like.

[0004] By the way, carbon monoxide (CO) and carbon dioxide (CO ２It has been investigated to methanate ZnO by reacting it with hydrogen and use the resulting methane as an energy resource. Patent Document 2, for example, proposes a methanation catalyst for such a reaction, which comprises a stabilized zirconia support having a tetragonal and / or cubic crystal structure and a stabilizing element solid-solubilized therein, and Ni supported on the stabilized zirconia support, where the stabilizing element is at least one transition element selected from the group consisting of Mn, Fe, and Co. Furthermore, as a raw material for the chemical industry, ethane is more desirable than methane, which has poor chemical reactivity. Patent Document 3, for example, proposes a photocatalyst for producing ethane from methane, which comprises a semiconductor having a band gap of 2.8 eV to 4.4 eV and gold particles (Au particles) supported on the semiconductor, where the semiconductor is one or more selected from the group consisting of zinc oxide and titanium oxide.

[0005] Japanese Patent No. 5774180 Japanese Patent Application Laid-Open No. 2018-20278 Japanese Patent Application Laid-Open No. 2022-77051

[0006] The methanation catalyst described in Patent Document 2 has a problem that the crystal structure is easily non-uniform depending on the manufacturing method. It also describes the need for metallic Ni supported on the surface of the methanation catalyst to be peeled off and separated from the methanation catalyst by the supply of a mixed gas, and for Ni ions of the stabilized zirconia support exposed from the peeled portion to be reduced to a metallic state. The photocatalyst described in Patent Document 3 can produce ethane from methane, but has problems with the production of CO and CO. ２ There is no disclosure of the production of ethane from a porous coordination polymer. Therefore, an object of the present invention is to provide a nickel-supported composite in which a nickel-based compound is supported on a porous coordination polymer, which has a uniform pore spatial structure and is capable of selectively adsorbing large amounts of gas, and which can be used as a catalyst for methane and ethane production, and a method for producing the same. Another object of the present invention is to provide a method for producing methane and ethane using the nickel-supported composite.

[0007] According to the present invention, there is provided a nickel-supported composite in which a nickel-based compound is supported on a porous coordination polymer, wherein the porous coordination polymer comprises a metal ion and an organic ligand, and the organic ligand has an imidazole skeleton.

[0008] In the nickel-supported composite of the present invention, it is preferable that: (1) the metal species of the metal ion is zinc; (2) the nickel-based compound contains at least one of metallic nickel, nickel nitrate, nickel oxide, and a composite containing zinc as well as nickel; (3) the mass ratio of zinc element to nickel element is in the range of 90:10 to 40:60; and (4) a calcium-based compound is further supported on the porous coordination polymer.

[0009] The present invention also provides a method for producing the nickel-supported composite, which comprises mixing a porous coordination polymer having an imidazole skeleton with nickel nitrate and / or nickel oxide, and then partially or completely reducing the nickel nitrate and / or nickel oxide to metallic nickel, thereby supporting a nickel-based compound comprising metallic nickel, nickel nitrate, and / or nickel oxide on the porous coordination polymer. In the method for producing the nickel-supported composite of the present invention, it is preferable to add calcium nitrate and / or calcium oxide together with the nickel nitrate and / or nickel oxide, and mix the resulting mixture with the porous coordination polymer having an imidazole skeleton.

[0010] The present invention also provides a method for producing methane and ethane, which comprises contacting the nickel-supported composite with a mixed gas containing carbon dioxide and / or carbon monoxide and hydrogen to produce methane and ethane. In the method for producing methane and ethane of the present invention, it is preferable to contact the mixed gas with the nickel-supported composite at a temperature of 200°C or higher.

[0011] The nickel-supported composite of the present invention has a nickel-based compound supported on a porous coordination polymer while maintaining the micropores of the porous coordination polymer, and has the excellent adsorption and storage performance inherent to the porous coordination polymer. The porous coordination polymer efficiently adsorbs and stores reactant gases, and the catalytic action of metallic nickel supported on the porous coordination polymer allows carbon monoxide (CO) and carbon dioxide (CO ２ ) to methane (CH ４ ) and ethane (C ２ H ６ ) can be efficiently produced. Furthermore, by supporting a calcium-based compound together with a nickel-based compound in the nickel-supported composite of the present invention, it is possible to promote the hydrogenation reaction of carbon dioxide, and the methane and ethane production reaction can be initiated at low temperatures, allowing for efficient production of methane and ethane. Furthermore, in the method for producing the nickel-supported composite of the present invention, the nickel-based compound can be efficiently supported without damaging the structure of the porous coordination polymer, i.e., while maintaining the micropores of the porous coordination polymer as described above.

[0012] (Porous Coordination Polymer) In the nickel-loaded composite of the present invention, the porous coordination polymer supporting the nickel-based compound comprises a metal ion and an organic ligand. In the present invention, it is particularly preferable to use a porous coordination polymer having an imidazole backbone. Many porous coordination polymers are unstable to water due to their coordinate bonding properties, but porous coordination polymers having an imidazole backbone have relatively excellent structural stability. In particular, ZIF (zeolite imidazolate structure) with an SOD topology has excellent structural stability. By using ZIF as a porous coordination polymer, it is possible to efficiently adsorb and store the mixed gas used as the raw material in the methane and ethane production reaction and to exhibit structural stability against water generated by side reactions.

[0013] The metal ions contained in the porous coordination polymer may be any ions capable of forming a coordinate bond with an organic ligand, and are not limited thereto. Examples of metal ions include Li, Na, K, Rb, Be, Mg, Ca, Sr, Ba, Sc, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, and Bi. At least one of these ions can be selected, and zinc (Zn) is particularly preferred, as described below.

[0014] The organic ligand may be any compound capable of forming a coordinate bond with a metal ion, but in the present invention, it is important that the organic ligand has an imidazole skeleton, and a compound having an imidazole skeleton formed of at least one selected from the group consisting of imidazole, 2-methylimidazole, benzimidazole, 2-formylimidazole, and 2,4,6-tri(4-pyridyl)-1,3,5-triazine is used. In the present invention, a porous coordination polymer having an excellent carbon dioxide storage capacity, in which the metal ion is a zinc ion and which is composed of an organic ligand having an imidazole skeleton, can be preferably used. Examples of such a porous coordination polymer include, but are not limited to, ZIF-8, ZIF-68, ZIF-69, and ZIF-70. Among these, ZIF-8 (metal ion: Zn ２＋ , organic ligand: 2-methylimidazole skeleton) can be preferably used.

[0015] The porous coordination polymer may be one produced by a known method, or a commercially available product.

[0016] The pore size of the porous coordination polymer is not particularly limited, but is preferably in the range of 0.3 nm to 2.0 nm. The specific surface area of ​​the porous coordination polymer is not particularly limited, but is preferably 50 m ２ / g to 3000m ２ The pore volume of the porous coordination polymer is preferably in the range of 0.010 m / g. ３ / g to 1.0m ３ It is preferable that the range of 1 / g is used.

[0017] (Nickel-Based Compound) In the nickel-supported composite of the present invention, the nickel-based compound supported on the porous coordination polymer can be any of a variety of compounds containing nickel, including, but not limited to, metallic nickel, nickel oxide, nickel halides such as chlorides, fluorides, and iodides, and nickel salts of inorganic acids such as nickel nitrate and nickel sulfate. It is particularly preferable that metallic nickel produced by reduction of a nickel-based compound and nickel nitrate or nickel oxide used as a raw material are supported. The nickel-based compound may also be a composite containing a metal other than nickel. Examples of metals other than nickel include zinc and copper. The nickel-based compound may also be an alloy of nickel and another metal, or a mixture of a nickel compound and a compound of another metal.

[0018] (Calcium-based Compound) In the nickel-supported composite of the present invention, a calcium-based compound may be supported together with the nickel-based compound, which makes it possible to promote the hydrogenation reaction of carbon monoxide and carbon dioxide, and the methane and ethane production reaction starts at a low temperature, thereby enabling efficient production of methane and ethane. Examples of calcium-based compounds include metallic calcium, calcium oxide, and calcium halides such as chlorides, fluorides, and iodides. In particular, it is preferable to support metallic calcium produced by reduction of a calcium-based compound, and calcium nitrate and / or calcium oxide, which are suitable raw materials.

[0019] (Nickel-supported Composite) As described above, in the nickel-supported composite of the present invention, a nickel-based compound such as metallic nickel is supported on a porous coordination polymer having an imidazole skeleton, and preferably supported on ZIF-8 as the porous coordination polymer. The nickel-supported composite cannot be unambiguously specified depending on the type of nickel-based compound used. However, when ZIF-8 is used as the porous coordination polymer, it is preferable that the mass ratio of zinc to nickel contained in the composite is in the range of 90:10 to 40:60, particularly 90:10 to 60:40. If the amount of nickel is less than this range, the methane and ethane production efficiency described below may not be sufficiently improved compared to when the amount is within the above range. On the other hand, if the amount of nickel is greater than this range, the excellent adsorption and storage effects of the porous coordination polymer may not be fully achieved compared to when the amount is within the above range, and the methane and ethane production efficiency may not be sufficiently improved.

[0020] Furthermore, when a calcium-based compound is supported together with a nickel-based compound, and ZIF-8 is used as the porous coordination polymer, it is desirable to replace 0.01 to 98.0 mass% of the nickel content with calcium in the mass ratio of zinc to nickel contained in the composite. Specifically, but not limited to, the mass ratio of zinc, nickel, and calcium is preferably in the range of 1.00:0.01:0.01 to 1.00:0.60:6.00, particularly 1.00:0.10:2.00 to 1.00:0.50:5.00.

[0021] The pore size of the nickel-supported composite is not particularly limited, but it is preferable that the pore size of the porous coordination polymer is maintained, and it is preferable that the pore size is in the range of 0.3 nm to 1.5 nm. The specific surface area of ​​the nickel-supported composite is not particularly limited, but it is preferable that the specific surface area is 50 m ２ / g to 2000m ２ The pore volume of the nickel-supported composite is preferably in the range of 0.010 m / g. ３ / g to 0.7m ３It is preferable that the range of 1 / g is used.

[0022] (Method for Producing Nickel-Loaded Composites) The nickel-loaded composites of the present invention can be produced by mixing a nickel-based compound, preferably nickel nitrate and / or nickel oxide, with a porous coordination polymer having an imidazole skeleton to load the nickel-based compound on the porous coordination polymer, and then reducing a portion or all of the nickel nitrate and / or nickel oxide to metallic nickel. As described above, to obtain a nickel-loaded composite that also loads a calcium-based compound together with a nickel-based compound, the calcium-based compound can be added to a porous coordination polymer having an imidazole skeleton and mixed with the porous coordination polymer having an imidazole skeleton to produce a porous coordination polymer loaded with both a nickel-based compound and a calcium-based compound.

[0023] [Mixing Step] The nickel-based compound, and optionally the calcium-based compound, and the porous coordination polymer are mixed in an alcohol-based solvent or a mixed solvent of water and an alcohol-based solvent by stirring for, for example, 10 to 120 minutes at room temperature and atmospheric pressure. Examples of alcohol-based solvents include methanol, ethanol, n-propanol, and isopropanol, with methanol being particularly preferred. When using a mixed solvent of water and an alcohol-based solvent, the water:alcohol (mass ratio) is preferably in the range of 1:0.01 to 1:2, depending on the type of alcohol used. In this specification, "room temperature (15 to 25°C) and atmospheric pressure" refers to a state in which neither heating nor pressure is intentionally applied, and is equivalent to room temperature and atmospheric pressure.

[0024] The amount of the nickel-based compound and the porous coordination polymer in the mixed solution varies depending on the types of porous coordination polymer and nickel-based compound used and cannot be generally defined, but is preferably in the range of 1.0:0.10 to 1.0:1.0 (molar ratio). Furthermore, when a calcium-based compound is mixed with the nickel-based compound, the amount varies depending on the types of nickel-based compound and calcium-based compound used and cannot be generally defined, but is preferably in the range of 1.0:0.01 to 1.0:6.0 (molar ratio). Furthermore, while there are no limitations as long as the porous coordination polymer is soluble in the solvent, it is preferable that the porous coordination polymer be added to the solvent in a range of 0.01 to 0.1 g / mL. The nickel-based compound and the porous coordination polymer can be mixed using a known mixer such as an anchor mixer, planetary mixer, or Henschel mixer, as well as a stirrer.

[0025] [Solvent Removal and Reduction Step] Next, the solvent is removed from the solution containing the porous coordination polymer on which the nickel-based compound has been supported by mixing. Solvent removal can be achieved by conventional methods such as filtration, sedimentation, or evaporation to dryness. After the solvent is removed, the mixture is heated at 100 to 300°C for 30 to 120 minutes. This completely removes any remaining solvent, and converts the nickel-based compound supported on the porous coordination polymer to metallic nickel using the reducing gas generated by thermal decomposition of the organic ligands constituting the porous coordination polymer, producing a nickel-supported composite in which metallic nickel is supported on the porous coordination polymer. The nickel-based compound can be converted to metallic nickel by heating the nickel-based compound in a reducing gas atmosphere such as hydrogen gas, or by using a reducing agent, in addition to the thermal decomposition described above. The nickel-based compound-supported composite thus obtained is a composite in which metallic calcium and the calcium compound, which is a raw material component, are supported on a porous coordination composite having an imidazole skeleton when mixed with metallic nickel, a nickel compound (nickel nitrate or nickel oxide), which is a raw material component, and a calcium-based compound.

[0026] (Production of methane and ethane) The nickel-supported composite of the present invention can be used to produce methane and ethane by reacting carbon dioxide (CO ２ The porous coordination polymer having an imidazole skeleton, which has the property of adsorbing and storing carbon monoxide (CO), supports nickel, which serves as a catalyst for producing methane and ethane. Therefore, the porous coordination polymer can be suitably used as a catalyst for producing methane and ethane. Specifically, by reacting a mixed gas containing carbon dioxide and / or carbon monoxide and hydrogen with the nickel-supported composite of the present invention, the carbon dioxide and / or carbon monoxide adsorbed and stored in the pores of the porous coordination polymer having an imidazole skeleton are converted to methane and ethane by the catalytic action of the supported nickel, according to the following formula: ２ +4H ２ →xCH ４ +yC ２ H ６ +zH ２ O CO + 4H ２ →aCH ４ +bC ２ H ６ +cH ２ Like O 2 , it reacts with hydrogen in the gas mixture to produce methane and ethane.

[0027] The above reaction is carried out by filling a reaction tube with the nickel-supported composite of the present invention, and then supplying a mixed gas to the reaction tube while maintaining a reaction temperature of 200°C or higher, particularly 200 to 300°C, under atmospheric pressure for 10 to 180 minutes. Specifically, it is preferable to raise the temperature to the reaction temperature at a rate of 1 to 10°C / min. Furthermore, as mentioned above, when a composite supporting a nickel-based compound and a calcium-based compound is used, the above reaction can be initiated at a low temperature. Therefore, methane and ethane can be produced by maintaining a reaction temperature of 100°C or higher, particularly 150 to 300°C, under atmospheric pressure for 10 to 180 minutes. Since the nickel-supported composite of the present invention itself supports metallic nickel, it can be used as is. However, it is preferable to pretreat it with a reducing gas such as hydrogen gas at a temperature of 200 to 300°C for 5 to 30 minutes. This increases the amount of metallic nickel in the nickel-supported composite, thereby improving catalytic activity and enabling efficient production of methane and ethane. The mixed gas used is a gas containing at least carbon dioxide and / or carbon monoxide, and hydrogen, and preferably further contains an inert gas such as helium as a flow gas. ２ and / or CO:H ２ The ratio of He to Ni is preferably in the range of 0.1 to 2.0:0.4 to 8.0:9.5 to 0.0, and it is particularly preferable to use a mixed gas of 1:4:5. The flow rate of the mixed gas can be adjusted appropriately depending on the amount of nickel-supported composite, and it is preferable to flow the mixed gas at a rate of 1 to 20 sccm (Standard cc / min) per 100 mg of nickel-supported composite.

[0028] In order to explain the present invention in more detail, examples carried out by the present inventors will be described below.

[0029] (Measurement Method) [Gas Adsorption / Desorption Behavior / Pore Structure Evaluation] For the nickel-supported composite, nitrogen gas adsorption isotherms were measured at liquid nitrogen temperature by a multipoint method using a BELSORP MAX II type manufactured by Microtrackbell Co., Ltd., to evaluate the gas adsorption / desorption behavior. In addition, the average pore diameter, specific surface area, and pore volume were measured by the MP method and the BET method, and the pore structure was evaluated.

[0030] [Evaluation of Crystalline and Amorphous Structure] The crystalline structure of the nickel-loaded composite was evaluated by powder X-ray diffraction (PXRD) using a SmartLab manufactured by Rigaku Corporation.

[0031] [Thermogravimetric analysis evaluation] The nickel-supported composite was subjected to thermogravimetric analysis evaluation in a nitrogen atmosphere using a Hitachi TG / DTA7220 at a temperature rise rate of 5° C. / min and at measurement temperatures of 30° C. to 900° C. In addition, the presence or absence of nickel-based compounds and calcium-based compounds was evaluated based on the thermogravimetric change measured by the thermogravimetric analysis method.

[0032] [Fluorescent X-ray evaluation] The metal elements contained in the nickel-supported composite were evaluated by qualitative measurement of the powder using a ZSX Primus IV manufactured by Rigaku Corporation. Measurement target: Ni-Ka ray, Zn-Ka ray, Ca-Ka ray Measurement diameter: 10 mm Measurement X-ray: Rh (4.0 kW)

[0033] [Catalytic Performance Evaluation] The nickel-supported composite was measured using BELCAT II and BELMASS manufactured by Microtrackbell at temperatures of 200°C to 300°C. Pretreatment conditions: reduction under hydrogen gas at 300°C for 60 minutes Gas flow rate: 20 sccm Reaction gas: CO ２ : H ２ : He = 1:4:5 Temperature increase: 5 ° C. / min

[0034] Preparation and Evaluation of Nickel-Supported Composite Example 1 Ethanol was added to a 140 ml container (mayonnaise bottle), and then ZIF-8 (Sigma-Aldrich Japan LLC; Basolite® Z1200) and nickel (II) nitrate hexahydrate were added to the container and dissolved at room temperature to form a solution. A stirrer was then added to the solution, and the mixture was stirred for 60 minutes to obtain a suspension containing ZIF-8 supporting nickel metal. The resulting suspension was transferred to a crucible and fired on a hot plate at 100°C to form a solid product, thereby obtaining nickel-supported composite A according to Example 1. The molar ratio of the components in the solution was ZIF-8: nickel (II) nitrate hexahydrate: ethanol = 1.00:0.20:96.80. The resulting nickel-supported composite A was found to be a microporous material based on gas adsorption / desorption behavior and pore structure evaluation. The average pore diameter, specific surface area, and pore volume are shown in Table 1. PXRD measurement confirmed that nickel-supported composite A had a ZIF-8, metallic nickel, and nickel oxide structure. Thermogravimetric analysis showed that nickel-supported composite A had a decreasing TG curve in the temperature range of 330°C to 400°C, indicating that it contained nickel nitrate. X-ray fluorescence analysis showed that nickel-supported composite A had a mass ratio of Ni:Zn = 13.7:86.3. Catalytic performance evaluation showed that nickel-supported composite A produced methane and ethane from the reaction gas.

[0035] Example 2 Nickel-supported composite B was obtained in the same manner as in Example 1, except that the molar ratio of each component in the solution was ZIF-8:nickel(II) nitrate hexahydrate:ethanol = 1.00:0.78:155.37. The obtained nickel-supported composite B was found to be a microporous material based on gas adsorption / desorption behavior and pore structure evaluation. The average pore diameter, specific surface area, and pore volume are shown in Table 1. PXRD measurement confirmed that nickel-supported composite B had ZIF-8, metallic nickel, and a nickel oxide structure. Thermogravimetric analysis revealed that nickel-supported composite B exhibited a decreasing TG curve in the temperature range of 330°C to 400°C, indicating that it contained nickel nitrate. X-ray fluorescence analysis revealed that nickel-supported composite B had a mass ratio of Ni:Zn = 36.8:63.2. Catalytic performance evaluation showed that nickel-supported composite B produced methane and ethane from the reaction gas.

[0036] Example 3 Nickel-supported composite C was obtained in the same manner as in Example 1, except that the solid product was calcined in a muffle furnace at 300°C for 1 hour and the molar ratio of the components in the solution was set to ZIF-8:nickel(II) nitrate hexahydrate:ethanol = 1.00:0.20:96.96. The obtained catalyst C for methane and ethane reaction was found to be a microporous material based on gas adsorption / desorption behavior and pore structure evaluation. The average pore diameter, specific surface area, and pore volume are shown in Table 1. PXRD measurement confirmed that nickel-supported composite C had ZIF-8, metallic nickel, and a nickel oxide structure. Thermogravimetric analysis showed that nickel-supported composite C did not have a decreasing TG curve in the temperature range of 330°C to 400°C. X-ray fluorescence analysis showed that nickel-supported composite C had a mass ratio of Ni:Zn = 14.4:85.6. The catalytic performance evaluation showed that the nickel-supported composite C produced methane and ethane from the reaction gas.

[0037] Comparative Example 1 Composite D was obtained in the same manner as in Example 1, except that the molar ratio of each component in the solution was ZIF-8: nickel (II) nitrate hexahydrate: ethanol = 1.00:0.00:77.76. The gas adsorption / desorption behavior and pore structure evaluation of the obtained Composite D indicated that it was a material having micropores. The average pore diameter, specific surface area, and pore volume are shown in Table 1. PXRD measurement confirmed that Composite D had a ZIF-8 structure. Thermogravimetric analysis indicated that Composite D did not have a decreasing TG curve in the temperature range of 330°C to 400°C. X-ray fluorescence analysis indicated that Composite D had a mass ratio of Ni:Zn = 0:100.0. Catalytic performance evaluation indicated that Composite D did not produce methane or ethane from the reaction gas.

[0038]

[0039] Example 4 Ethanol was added to a 140 ml container (mayonnaise bottle), and then ZIF-8, nickel (II) nitrate hexahydrate, and calcium nitrate tetrahydrate were added to the container and dissolved at room temperature to form a solution. A stirrer was then added to the solution and stirred for 24 hours to obtain a suspension containing ZIF-8 loaded with nickel and calcium metals. The resulting suspension was transferred to a crucible and fired on a hot plate at 100°C to form a solid product. After the solid product was obtained, it was fired in a muffle furnace at 300°C for 1 hour to obtain a nickel- and calcium-loaded composite E according to Example 4. The molar ratio of each component in the solution was ZIF-8: nickel (II) nitrate hexahydrate: calcium nitrate tetrahydrate: ethanol = 1.00:0.23:11.36:197.30. The resulting nickel- and calcium-loaded composite E was found to be a microporous material based on gas adsorption / desorption behavior and pore structure evaluation. PXRD measurement confirmed that nickel and calcium-supported composite E had a ZIF-8 framework. Thermogravimetric analysis showed that nickel and calcium-supported composite E had a decreasing TG curve in the temperature range of 320°C to 400°C, indicating that it contained metal nitrates. X-ray fluorescence analysis showed that nickel and calcium-supported composite E had a mass ratio of Ca:Ni:Zn = 76.9:3.9:19.2. Catalytic performance evaluation showed that nickel and calcium-supported composite E produced methane and ethane from reaction gases at reaction temperatures of approximately 100°C.

Claims

1. A nickel-loaded composite in which a nickel-based compound is loaded onto a porous coordination polymer, wherein the porous coordination polymer comprises a metal ion and an organic ligand, and the organic ligand has an imidazole skeleton.

2. The nickel-loaded composite according to claim 1, wherein the metal species of said metal ions is zinc.

3. The nickel-loaded composite according to claim 1 or 2, wherein the nickel-based compound comprises at least one of metallic nickel, nickel nitrate, nickel oxide, and a composite containing nickel and zinc.

4. The nickel-loaded composite according to claim 2 or 3, wherein the mass ratio of zinc element to nickel element is in the range of 90:10 to 40:

60.

5. The nickel-loaded composite according to claim 1, wherein said porous coordination polymer further loads a calcium-based compound.

6. A method for producing a nickel-loaded composite according to claim 1, characterized in that the porous coordination polymer having an imidazole skeleton is mixed with nickel nitrate and / or nickel oxide, and then a part or all of the nickel nitrate and / or nickel oxide is reduced to metallic nickel, thereby loading a nickel-based compound consisting of metallic nickel, nickel nitrate and / or nickel oxide onto the porous coordination polymer.

7. A method for producing a nickel-loaded composite according to claim 6, wherein calcium nitrate and / or calcium oxide is added together with the nickel nitrate and / or nickel oxide, and mixed with the porous coordination polymer having an imidazole skeleton.

8. A method for producing methane and ethane, comprising reacting the nickel-supported composite of claim 1 with a mixed gas containing carbon dioxide and / or carbon monoxide and hydrogen to produce methane and ethane.

9. The method for producing methane and ethane according to claim 8, wherein the mixed gas is contacted with the nickel-supported composite at a temperature of 200°C or higher.

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