Ni / CeO2 catalyst and method for producing the same, and method for producing methane.

Abstract

The present invention relates to providing a Ni / CeO2 catalyst with a high surface area, a method for producing the same, and a novel method for producing methane using the Ni / CeO2 catalyst. [Solution] A method for producing a Ni / CeO2 catalyst by the sol-gel method, (1) A step of preparing a precursor by heating a solution containing Ni and Ce components. Step (2) involves calcining the precursor obtained in step (1) at 400°C to 900°C. A manufacturing method that includes this.

Description

[Technical Field]

[0001] The present invention relates, for example, to a Ni / CeO2 catalyst with a high surface area suitable for methanation, a method for producing the same, and a highly efficient method for producing methane using the above Ni / CeO2 catalyst. [Background technology]

[0002] Methanation, the process of converting carbon dioxide into methane fuel, is attracting attention from a carbon neutrality perspective. To date, catalysts with nickel or ruthenium supported on high-surface-area supports have been used as highly active catalysts (see, for example, Patent Document 1).

[0003] This methanation reaction is exothermic, favoring low temperatures. At high temperatures, byproduct formation and catalyst deactivation due to sintering occur, so the development of catalysts that are highly active at lower temperatures is desired. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] E. Garcia-Bordeje et al., Nanomaterials, 12, 1052 (2022). [Overview of the project] [Problems that the invention aims to solve]

[0005] In light of these circumstances, the present invention relates to a method for producing a Ni / CeO2 catalyst with a high surface area.

[0006] Furthermore, the present invention relates to providing, for example, a Ni / CeO2 catalyst with a high surface area that enables methanation in a lower temperature range than conventional catalysts.

[0007] Furthermore, the present invention relates to providing a novel method for producing methane using the above-mentioned Ni / CeO2 catalyst.

Means for Solving the Problems

[0008] As a result of intensive studies to solve the above problems, the present inventors have succeeded in developing a Ni / CeO₂ catalyst with a high specific surface area and have completed the present invention.

[0009] That is, the present invention provides a method for producing the following Ni / CeO₂ catalyst.

[0010] [1] A method for producing a Ni / CeO₂ catalyst by the sol-gel method, comprising: Step (1) of heating a solution containing Ni component and Ce component to prepare a precursor; Step (2) of firing the precursor obtained in Step (1) at 400°C to 900°C. A production method comprising the above steps.

[0011] [2] The production method according to [1], wherein the Ni component contains a nickel salt.

[0012] [3] The production method according to [1], wherein the Ni component contains nickel nitrate, nickel acetate, nickel chloride, nickel sulfate, nickel oxalate, nickel bromide, nickel carbonate, or a plurality of them.

[0013] [4] The production method according to [1], wherein the Ce component contains a cerium salt.

[0014] [5] The production method according to [1], wherein the Ce component contains cerium nitrate, cerium acetate, cerium chloride, cerium sulfate, cerium oxalate, cerium perchlorate, or a plurality of them.

[0015] [6] The production method according to [1], wherein the sol-gel method is the citric acid method.

[0016] [7] The manufacturing method according to claim 1, wherein the solution is an aqueous solution.

[0017] [8] The manufacturing method according to [1], wherein the solution further contains ethylene glycol.

[0018] [9] The manufacturing method according to [1], wherein the firing temperature in step (2) is 500°C to 800°C.

[0019]

[10] The manufacturing method according to [1], wherein the Ni content in the obtained Ni / CeO2 catalyst is 5 to 20 wt%.

[0020]

[11] The manufacturing method according to [1], wherein the CeO2 content in the obtained Ni / CeO2 catalyst is 50 to 95 wt%.

[0021]

[12] The manufacturing method according to [1], further including step (3) of reducing the Ni / CeO2 catalyst obtained in step (2) after step (2).

[0022] Furthermore, the present invention provides a method for manufacturing methane as follows.

[0023]

[13] A method for manufacturing methane, including step (4) of flowing CO2 gas and H2 gas at 130°C to 400°C in the presence of a Ni / CeO2 catalyst obtained by the manufacturing method according to any one of [1] to

[12] .

[0024] Furthermore, the present invention provides a Ni / CeO2 catalyst as follows.

[0025]

[14] A Ni / CeO2 catalyst, which is a catalyst containing CeO2 and Ni and has a surface area of 50 m 2 / g or more.

[0026]

[15] The Ni / CeO2 catalyst described in

[14] , wherein the Ni content is 5-20 wt%.

[0027]

[16] The Ni / CeO2 catalyst described in

[14] , wherein the CeO2 content is 50-95 wt%. [Effects of the Invention]

[0028] The present invention provides a method for producing a Ni / CeO2 catalyst that, by including the novel steps described above, can produce a Ni / CeO2 catalyst with a high surface area.

[0029] Furthermore, the Ni / CeO2 catalyst of the present invention is a novel catalyst with a high surface area, enabling, for example, more efficient methanation than conventional catalysts.

[0030] Furthermore, because the methane production method of the present invention uses the above-mentioned Ni / CeO2 catalyst, methanation becomes possible in a lower temperature range than conventional methods, for example. [Brief explanation of the drawing]

[0031] [Figure 1] Figure 1 shows the procedure for preparing a Ni / CeO2 catalyst by the sol-gel method in the examples described herein. [Figure 2] Figure 2 shows the procedure for preparing the Ni / CeO2 catalyst by impregnation in the examples described herein. [Figure 3] Figure 3 shows the treatment and evaluation procedures using the Ni / CeO2 catalyst in the examples described herein. [Figure 4] Figure 4 shows the XRD patterns obtained from XRD measurements using each Ni / CeO2 catalyst in Example 1 (Ni / CeO2-1) and Comparative Example 1 (Ni / CeO2-2) of this specification. [Figure 5] Figure 5 is a graph showing the results of the CO2 conversion rate using each Ni / CeO2 catalyst in Example 1 and Comparative Example 1 of this specification. [Figure 6]Figure 6 is a graph showing the selectivity results for CO and CH4 using the Ni / CeO2 catalyst obtained in Example 1 of this specification. [Figure 7] Figure 7 is a graph showing the results of the CH4 conversion rates using each Ni / CeO2 catalyst in Example 2 (15wt%Ni / CeO2-600) and Comparative Example 2 (15wt%Ni / CeO2-imp) of this specification. [Figure 8] Figure 8 shows the XRD patterns obtained from XRD measurements using each Ni / CeO2 catalyst in Example 2 and Comparative Example 2 of this specification. [Figure 9] Figure 9 is a graph showing the conversion rates for each Ni / CeO2 catalyst (10wt%Ni / CeO2-600 catalyst) in Example 3. [Figure 10] Figure 10 is a graph showing the conversion rates for each Ni / CeO2 catalyst with different Ni loading amounts obtained in Example 4 (5wt%Ni / CeO2-600, 10wt%Ni / CeO2-600, 15wt%Ni / CeO2-600, 20wt%Ni / CeO2-600). [Figure 11] Figure 11 shows the XRD patterns obtained from XRD measurements using each Ni / CeO2 catalyst with a different Ni loading amount (5wt%Ni / CeO2-600, 10wt%Ni / CeO2-600, 15wt%Ni / CeO2-600, 20wt%Ni / CeO2-600) in Example 5. [Figure 12] Figure 12 is a graph showing the CO2 conversion rates for each Ni / CeO2 catalyst with different Ni loading amounts (5wt%Ni / CeO2-600, 10wt%Ni / CeO2-600, 15wt%Ni / CeO2-600, 20wt%Ni / CeO2-600) in Example 5. [Figure 13] Figure 13 shows the XRD patterns obtained from XRD measurements using each Ni / CeO2 catalyst (15wt%Ni / CeO2-600) in Example 6 at different calcination temperatures (500°C, 600°C, 700°C, 800°C). [Figure 14]Figure 14 is a graph showing the CO2 conversion rates obtained using each Ni / CeO2 catalyst (15wt%Ni / CeO2-600) at different calcination temperatures (500°C, 600°C, 700°C, 800°C) in Example 6. [Modes for carrying out the invention]

[0032] The embodiments of the present invention will be described in detail below.

[0033] [Method for producing Ni / CeO2 catalyst] The present invention is a method for producing a Ni / CeO2 catalyst by the sol-gel method, (1) A step of preparing a precursor by heating a solution containing Ni and Ce components. Step (2) involves calcining the precursor obtained in step (1) at 400°C to 900°C. Includes.

[0034] The present invention's method for producing a Ni / CeO2 catalyst, by including the novel steps described above, allows for the simple production of a Ni / CeO2 catalyst with a higher surface area than, for example, a Ni / CeO2 catalyst produced by a conventional solution method.

[0035] In this invention, for example, we surmise that the simultaneous metal-supported catalyst formation as a solution containing Ni and Ce components is also involved in the high surface area, but we do not limit the scope of our rights to only the above mechanism.

[0036] Step (1) described above is a step of preparing a precursor by heating a solution containing Ni and Ce components. The method of preparing the precursor by heating the solution can be any known or novel method, as long as it does not impair the effects of the present invention.

[0037] In step (1) above, the solution contains Ni and Ce components. The solution only needs to contain Ni and Ce components.

[0038] In step (1) above, known or novel methods can be used as the Ni component, as long as they do not impair the effects of the present invention. In particular, the Ni component is preferably one that includes a nickel salt. In the present invention, the nickel salt includes hydrates and solvates, as well as salts and complexes containing the element nickel. Furthermore, if the above solution is an aqueous solution, the Ni component is preferably one that is water-soluble.

[0039] Examples of the above Ni component include nickel nitrate, nickel acetate, nickel chloride, nickel sulfate, nickel oxalate, nickel bromide, nickel carbonate, or a combination thereof. In the present invention, the above Ni component also includes solvates such as its hydrated form. Among the above Ni components, examples of preferred components include nickel nitrate, nickel acetate, nickel chloride, nickel sulfate, and nickel carbonate.

[0040] More specifically, the above Ni components can include, for example, nickel nitrate dihydrate, nickel nitrate hexahydrate, nickel acetate tetrahydrate, nickel chloride dihydrate, nickel chloride hexahydrate, nickel sulfate hexahydrate, nickel sulfate heptahydrate, nickel oxalate dihydrate, nickel bromide hexahydrate, and the like.

[0041] In step (1) above, known or novel methods can be used as the Ce component, as long as they do not impair the effects of the present invention. In particular, the Ce component is preferably one that contains a cerium salt. In the present invention, the cerium salt includes hydrates and solvates, as well as salts and complexes containing the element cerium. Furthermore, if the above solution is an aqueous solution, a water-soluble Ce component is preferred.

[0042] Furthermore, in the present invention, it is preferable that the Ni content in the total metal components in the above solution is, for example, 5 to 20 wt%. Depending on the purpose and application, the above content can be in the mass percentage range between any two points such as 5 wt%, 5.1 wt%, 5.3 wt%, 5.5 wt%, 5.7 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 17.5 wt%, 18 wt%, 18.5 wt%, 19 wt%, 19.5 wt%, and 20 wt%.

[0043] The Ce component mentioned above can include cerium nitrate, cerium acetate, cerium chloride, cerium sulfate, cerium oxalate, cerium perchlorate, or a combination thereof. In the present invention, the Ce component also includes solvates such as its hydrated form. Among the Ce components, cerium nitrate, cerium acetate, cerium chloride, cerium sulfate, cerium oxalate, and the like are particularly preferred.

[0044] More specifically, the Ce component mentioned above can include, for example, cerium nitrate hexahydrate, cerium nitrate notahydrate, cerium acetate tetrahydrate, cerium acetate heptahydrate, cerium chloride hexahydrate, cerium chloride heptahydrate, cerium sulfate octahydrate, nickel oxalate decahydrate, cerium perchlorate hexahydrate, and the like.

[0045] Furthermore, in the present invention, it is preferable that the CeO2 content in the total metal components in the above solution is, for example, 50 to 95 wt%. Depending on the purpose and application, the above content can be in the mass percentage range between any two points such as 50 wt%, 51 wt%, 53 wt%, 55 wt%, 57 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, and 95 wt%.

[0046] In the present invention, known or novel methods can be used as the sol-gel method, as long as they do not impair the effects of the present invention. Examples of the above sol-gel methods include the citric acid method (citric acid sol-gel method), solution combustion method, peptization method, alkoxide method, hydrothermal sol-gel method, epoxy method (polyol method), etc. Among these, the citric acid method can be cited as preferred.

[0047] The above citric acid method may utilize known or novel methods as appropriate, as long as they do not impair the effects of the present invention. The above citric acid method prepares a solution by adding, for example, the above Ni and Ce components of the starting materials, citric acid, distilled water or ion-exchanged water, and optionally an auxiliary agent such as ethylene glycol.

[0048] More specifically, the above solution is stirred, for example, so that the Ni and Ce components dissolve (even if some suspended or supplemental components are present, they can be used depending on the purpose and application, as long as they do not impair the effects of the present invention), and citric acid is added in proportion to the molar ratio of the metal salt (for example, generally the molar ratio of citric acid to metal ions is 1:1 to 2:1, etc. Also, for example, in the embodiment of this application, the molar ratio of citric acid to metal ions is 10:1, etc.). In addition, an auxiliary agent such as ethylene glycol is added as needed. Next, the solvent of the above solution is gradually evaporated. As concentration progresses, a highly viscous sol is formed, and stirring is continued to obtain a uniform sol. When the above sol is further heated (usually the heating temperature is 80 to 120°C, etc.), the solvent is completely removed and a gel is formed. Next, the above precursors can be prepared by pre-calcination (for example, gradually heating the gel to decompose and burn the organic components (citric acid and ethylene glycol). Pre-calcination temperature: for example, 200-400°C) and main calcination (for example, further heating the powder obtained in pre-calcination to obtain the desired oxide or complex oxide. Calcination temperature: for example, 500-1000°C (depending on the material)) as needed.

[0049] In the present invention, the above-mentioned precursor refers to a material that can become a Ni / CeO2 catalyst through a subsequent calcination process.

[0050] In the present invention, the above solution is preferably one in which the Ni component and the Ce component can be dissolved. The above solution can be, for example, an aqueous solution or a solution containing an organic solvent, but for example, an aqueous solution is preferred. Depending on the purpose and application, the above aqueous solution may contain organic solvents such as alcohols or amines.

[0051] As the above-mentioned organic solvent, any known organic solvent can be used without particular limitation, as long as it does not impair the effects of the present invention. Examples of such organic solvents include alcohols such as methanol and ethanol, ammonia, and amines such as triethylamine and triethanolamine.

[0052] In step (1) above, the heating can be, for example, done by heating at 60°C to 200°C. The heating can also be done by, for example, placing a container such as a beaker containing the solution on a hot plate at 60°C, 80°C, 90°C, 100°C, 120°C, 150°C, etc.

[0053] In the present invention, the above solution preferably further contains glycols such as ethylene glycol and propylene glycol. As the ethylene glycol, any known ethylene glycol can be used as appropriate without particular limitations. These may be used individually or in combination of two or more types.

[0054] Step (2) described above is a step of calcining the precursor obtained in step (1) at 400°C to 900°C. Any known or novel method can be used for calcining the precursor, as long as it does not impair the effects of the present invention.

[0055] In step (2) above, the calcination of the precursor is carried out at, for example, 400°C to 900°C. The calcination temperature can be any two points in the temperature range, such as 400°C, 425°C, 450°C, 475°C, 500°C, 525°C, 550°C, 575°C, 600°C, 625°C, 650°C, 675°C, 700°C, 725°C, 750°C, 775°C, 800°C, 825°C, 850°C, 875°C, and 900°C, depending on the intended use and application. The calcination temperature is preferably, for example, 500°C to 800°C.

[0056] Furthermore, in the present invention, it is preferable that the Ni content in the obtained Ni / CeO2 catalyst is, for example, 5 to 20 wt%. Depending on the purpose and application, the above content can be in the mass percentage range between any two points such as 5 wt%, 5.1 wt%, 5.3 wt%, 5.5 wt%, 5.7 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 17.5 wt%, 18 wt%, 18.5 wt%, 19 wt%, 19.5 wt%, and 20 wt%.

[0057] Furthermore, in the present invention, it is preferable that the CeO2 content in the obtained Ni / CeO2 catalyst is, for example, 50 to 95 wt%. Depending on the purpose and application, the above content can be in the mass percentage range between any two points such as 50 wt%, 51 wt%, 53 wt%, 55 wt%, 57 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, and 95 wt%.

[0058] Furthermore, in the above solution, other metal components other than the Ni and Ce components may be added, as long as they do not impair the effects of the present invention. Known or novel metal components can be used as these other metal components.

[0059] Examples of other metallic components mentioned above include alkaline earth metal components such as Ba, Mg, and Ca, and rare earth metal components such as La and Y.

[0060] In this invention, the term "Ni / CeO2 catalyst" refers to any catalyst containing Ni and CeO2. For example, even if the other metal components are present in greater quantities than the Ni and Ce components, they are still included in the Ni / CeO2 catalyst.

[0061] Furthermore, in the present invention, the respective content (content ratio) of Ni and CeO2 in the obtained Ni / CeO2 catalyst can be obtained in basically stoichiometric proportions to the Ni and Ce components in the solution during the initial setup.

[0062] Furthermore, the present invention may include a step (3) after step (2) in which the Ni / CeO2 catalyst obtained in step (2) is reduced.

[0063] In step (3), the reduction method may be a known or novel method as appropriate. Examples of such reduction methods include a method using hydrogen.

[0064] [Method for producing methane] The present invention provides a method for producing methane, which includes step (4) of passing CO2 gas and H2 gas through the Ni / CeO2 catalyst obtained by the above production method at a temperature of 130°C to 400°C.

[0065] Because the methane production method of the present invention uses the above-mentioned Ni / CeO2 catalyst, methanation can be performed in a lower temperature range than conventional methods, for example.

[0066] Step (4) is a step in which CO2 gas and H2 gas are circulated at a temperature of 130°C to 400°C in the presence of the Ni / CeO2 catalyst obtained by the above manufacturing method. The gas circulation method can be any known or novel method as appropriate. For example, the gas circulation method can be carried out using a fixed-bed flow reactor at atmospheric pressure.

[0067] In step (4), the flow of the gas in the presence of the Ni / CeO2 catalyst is preferably carried out at a temperature of 130°C to 400°C. The temperature range can be any two points between 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, and 400°C. The temperature range may also be, for example, 200°C to 400°C, 250°C to 350°C, etc.

[0068] In step (4), known CO2 gas and H2 gas can be used as appropriate. Furthermore, there are no particular limitations as long as the CO2 gas and H2 gas react sequentially or simultaneously in the presence of the Ni / CeO2 catalyst to produce methane.

[0069] Furthermore, in step (4), the flow rate ratio of CO2 gas and H2 gas may be set to, for example, 1:10 to 10:1, 1:8 to 8:1, 1:6 to 6:1, 1:5 to 5:1, 1:4 to 4:1, 1:3 to 3:1, 1:2 to 2:1, 1:1, etc., depending on the purpose and application. For example, 1:4 can be given as a preferred flow rate ratio. In addition, depending on the purpose and application, other known gas components (for example, inert gases such as helium gas) may be used in combination.

[0070] [Ni / CeO2 catalyst] The Ni / CeO2 catalyst of the present invention is a catalyst comprising CeO2 and Ni, and has a surface area of ​​50 m². 2 It is 1 / g or more.

[0071] The above Ni / CeO₂ catalyst is a novel Ni / CeO₂ catalyst with a high surface area not found in the prior art. For example, it enables methanation in a lower temperature range than before.

[0072] The surface area of the above Ni / CeO₂ catalyst can be measured by BET measurement. The above BET measurement can be performed, for example, using (product name: BEL sorp - mini, manufacturer: MicrotracBEL) with a catalyst amount of 0.1 g.

[0073] The surface area of the above Ni / CeO₂ catalyst is preferably 50 m 2 / g or more. For example, it can be in the surface area range between any two points such as 50 m 2 / g, m 2 / g, 55 m 2 / g, 58 m 2 / g, 60 m 2 / g, 63 m 2 / g, 65 m 2 / g, 68 m 2 / g, 70 m 2 / g, 73 m 2 / g, 75 m 2 / g, 80 m 2 / g, 85 m 2 / g, 90 m 2 / g, etc.

[0074] The above Ni / CeO₂ catalyst can be easily obtained, for example, by using the above - mentioned method for manufacturing the Ni / CeO₂ catalyst.

[0075] Regarding the above Ni / CeO₂ catalyst, for elements not specifically described, each configuration described in the section on the method for manufacturing the above Ni / CeO₂ catalyst can be appropriately applied by reference.

[0076] Furthermore, the Ni content in the above Ni / CeO2 catalyst is preferably, for example, 5 to 20 wt%. Depending on the intended use and application, the above content can be in the mass percentage range between any two points, such as 5 wt%, 5.1 wt%, 5.3 wt%, 5.5 wt%, 5.7 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 17.5 wt%, 18 wt%, 18.5 wt%, 19 wt%, 19.5 wt%, and 20 wt%.

[0077] Furthermore, it is preferable that the CeO2 content in the above Ni / CeO2 catalyst is, for example, 50 to 95 wt%. Depending on the purpose and application, the above content can be in the mass percentage range between any two points such as 50 wt%, 51 wt%, 53 wt%, 55 wt%, 57 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, and 95 wt%. [Examples]

[0078] The following describes examples that specifically illustrate the structure and effects of the present invention. However, the content of the present invention is not limited to the following examples.

[0079] In the embodiment of this invention, each measurement and evaluation was performed as follows.

[0080] [GC-TCD measurement] In this embodiment, GC-TCD measurement was performed using a fixed-bed flow reactor at atmospheric pressure (product name: GC-8A, manufacturer: SHIMADZU), and the outlet gas after the reaction was analyzed (inlet temperature: 110°C, column temperature: 100°C, detector temperature: 110°C).

[0081] [BET measurement] In this example, BET measurement was performed using (product name: BEL sorp-mini, manufacturer: MicrotracBEL) with (catalyst amount: 0.1g).

[0082] [Example 1, Comparative Example 1] As Example 1 and Comparative Example 1, Ni / CeO2 catalysts were prepared by the sol-gel method and impregnation method, respectively, according to the procedures shown in Figures 1 and 2.

[0083] More specifically, in Example 1, Ni and Ce nitrate precursors were prepared using the citric acid method and then calcined at 600°C (Ni / CeO2-1). On the other hand, in Comparative Example 1, Ni was impregnated and supported onto CeO2 prepared by calcining at 600°C using the citric acid method, and then calcined at 600°C (Ni / CeO2-2).

[0084] More specifically, 42.0 g (200 mmol) of citric acid was placed in a 500 ml beaker, then 90 ml of deionized water was added and stirred until dissolved. Next, 8.67 g (20 mmol) of cerium nitrate hexahydrate was added to the dissolved solution and stirred until the cerium nitrate dissolved. Finally, 11.2 ml of ethylene glycol was added and stirred, then the specified number of moles of nickel nitrate hexahydrate were added and stirred until completely dissolved. The resulting solution was heated with a hot stirrer to obtain a viscous gel-like precursor. The obtained precursor was calcined (300°C, 1 hour) and then fired at 500-800°C for 10 hours to prepare the Ni / CeO2 catalyst.

[0085] XRD measurements were performed using the obtained Ni / CeO2 catalyst. Figure 4 shows the XRD pattern of the XRD measurement results.

[0086] Figure 4 shows the XRD measurement results of the Ni / CeO2 catalysts before H2 reduction. In all catalysts, a weak peak originating from NiO was observed, along with a peak corresponding to fluorite-type CeO2. The crystallite size of CeO2 (calculated using the (220) plane) determined by Scherrer's equation was 9.5 nm for the Ni / CeO2-1 catalyst and 19 nm for the Ni / CeO2-2 catalyst, indicating that the crystallinity of CeO2 in the Ni / CeO2-1 catalyst was low and the surface area was high.

[0087] Furthermore, the conversion of CO2 gas to methane using the Ni / CeO2 catalyst (methanation reaction) was carried out using a fixed-bed flow reactor at atmospheric pressure with a mixed gas of CO2 and H2 gas. More specifically, 0.2g of granular catalyst was reduced to H2 at 500°C, and then the reaction was carried out by flowing a 2.5% CO2 + 10% H2 mixed gas at 280-430°C. The outlet gas was analyzed by GC-TCD. Figure 5 shows a graph of the CO2 conversion rate using the Ni / CeO2 catalyst, and Figure 6 shows a graph of the selectivity of CO and CH4 using the Ni / CeO2 catalyst.

[0088] Figure 6 shows the CO2 conversion rate when methanation was performed using the prepared catalysts. For all catalysts, the CO2 conversion rate increased with increasing reaction temperature, reaching a maximum at around 300°C, and gradually decreasing at higher temperatures. The decrease in CO2 conversion rate at high temperatures is associated with the equilibrium conversion rate. The Ni / CeO2-1 catalyst showed a higher CO2 conversion rate in the temperature range of 280–430°C, indicating that the preparation method affects catalytic activity. The methane selectivity was nearly 100% for all catalysts between 280–370°C, but at higher temperatures, CO was produced via a reverse shift reaction (CO2 + H2 → CO + H2O), and its amount increased with increasing temperature.

[0089] [Example 2, Comparative Example 2] As Example 2, Ni / CeO2 catalysts for Example 2 (15wt%Ni / CeO2-600 (sol-gel method)) and Comparative Example 2 (15wt%Ni / CeO2-imp (impregnation method)) were prepared in the same manner as in Example 1.

[0090] Similar to Example 1, after reducing the sized catalyst to H2, the conversion to methane (methanation) by the Ni / CeO2 catalyst was carried out using a CO2 gas and H2 gas mixture in a fixed-bed flow reactor at atmospheric pressure. Figure 7 shows a graph of the CH4 conversion rate results using the Ni / CeO2 catalyst.

[0091] As shown in Figure 7, regarding the effect of the loading method on the CH4 conversion rate, it was found that the catalyst prepared by the sol-gel method showed a higher CH4 conversion rate than the catalyst prepared by the impregnation method.

[0092] Furthermore, similar to Example 1, XRD measurements were performed using the obtained Ni / CeO2 catalyst. Figure 8 shows the XRD patterns of the XRD measurement results. Also, in Figure 8, the 58m of Example 2 (15wt%Ni / CeO2-600) is shown. 2 / g, Comparative Example 2 (15wt%Ni / CeO2-imp) 19m 2 / g represents the surface area measurement result in the BET measurement of each catalyst surface.

[0093] In Figure 8, a comparison of the XRD patterns of catalysts prepared by the impregnation method and the sol-gel method shows that the 15wt%Ni / CeO2 catalyst prepared by the sol-gel method suppressed the crystal growth of both CeO2 and NiO compared to the 15wt%Ni / CeO2 prepared by the impregnation method, suggesting an increase in the CH4 conversion rate during methanation.

[0094] [Example 3] As Example 3, a 10 wt% Ni / CeO2 catalyst was prepared by calcining at 600°C, similar to Example 1. After reducing the granular catalyst with H2, a methanation reaction was carried out using the Ni / CeO2 catalyst. Figure 9 shows the results of the methanation reaction (each conversion rate).

[0095] Figure 9 shows the results of a methanation reaction using a 10 wt% Ni / CeO2 catalyst calcined at 600°C. The CO2 conversion rate increased from around 190°C and reached a maximum at around 320°C. Above 320°C, the CO2 conversion rate decreased in line with the equilibrium conversion rate. Furthermore, in the temperature range of 150 to 390°C, almost no CO was produced, the CH4 selectivity was nearly 100%, and it was confirmed that the CH4 conversion rate and the CO2 conversion rate were almost the same.

[0096] [Example 4] As Example 4, Ni / CeO2 catalysts with different Ni loading amounts (5wt%Ni / CeO2-600, 10wt%Ni / CeO2-600, 15wt%Ni / CeO2-600, 20wt%Ni / CeO2-600) were prepared in the same manner as in Example 1. After reducing the granular catalysts with H2, a methanation reaction was carried out using the above Ni / CeO2 catalysts. Figure 10 shows the results of the methanation reaction (each conversion rate).

[0097] Figure 10 shows a comparison of the conversion rates to CH4 for Ni / CeO2 catalysts with different Ni loads. This result shows that the methane conversion rate increased with increasing Ni load. It is thought that the CH4 conversion rate increased because catalysts with lower Ni loads had fewer Ni / CeO2 interfaces, while increasing Ni loads resulted in a greater number of interfaces.

[0098] [Example 5] As Example 5, Ni / CeO2 catalysts with different Ni loading amounts (5wt%Ni / CeO2-600, 10wt%Ni / CeO2-600, 15wt%Ni / CeO2-600, 20wt%Ni / CeO2-600) were prepared in the same manner as in Example 1, and XRD measurements were performed using the above Ni / CeO2 catalysts. Figure 11 shows the XRD patterns of the above XRD measurement results. Also, in Figure 11, the surface area (m²) of each catalyst surface in the BET measurement is shown. 2 The measurement results for ( / g) are also shown.

[0099] Figure 11 shows the XRD patterns of Ni / CeO2 with different loading amounts before H2 reduction. In each catalyst, a peak originating from the fluorite structure CeO2, marked with a triangle, was observed. Furthermore, the NiO peak increased with increasing loading amount. Compared to the bottommost CeO2 alone, the peaks of the top four Ni-supported CeO2 samples are broadened, suggesting that the dispersed NiO suppressed the crystal growth of CeO2.

[0100] Furthermore, Ni / CeO2 catalysts with different Ni loading amounts (5wt%Ni / CeO2-600, 10wt%Ni / CeO2-600, 15wt%Ni / CeO2-600, and 20wt%Ni / CeO2-600) were prepared, and after reducing the granular catalysts with H2, a methanation reaction was carried out using the above Ni / CeO2 catalysts. Figure 12 shows the results of the methanation reaction (each conversion rate).

[0101] [Example 6] As Example 6, Ni / CeO2 catalysts (15wt%Ni / CeO2-600) were prepared at various calcination temperatures (500°C, 600°C, 700°C, 800°C) in the same manner as in Example 1, and XRD measurements were performed using the above Ni / CeO2 catalysts. Figure 13 shows the XRD patterns of the above XRD measurement results. Also, in Figure 13, the surface area (m²) of each catalyst surface in the BET measurement is shown. 2 The measurement results for ( / g) are also shown.

[0102] Figure 13 shows the results of evaluating the effect of firing temperature using 15wt%Ni / CeO2. It shows the XRD patterns of 15wt%Ni / CeO2 catalysts fired at different firing temperatures. From these results, it was found that the peaks for CeO2 and NiO gradually increased with increasing firing temperature from 500 to 800°C, indicating that the crystallinity of both NiO and CeO2 increased.

[0103] Furthermore, Ni / CeO2 catalysts obtained at the above-mentioned calcination temperatures (500°C, 600°C, 700°C, and 800°C) were prepared, and after reducing the granular catalysts to H2, a methanation reaction was carried out using the above Ni / CeO2 catalysts. Figure 14 shows the results of the methanation reaction (each conversion rate).

[0104] Figure 14 shows the CH4 conversion rates of 15wt% Ni / CeO2 catalysts at different calcination temperatures. The CH4 conversion rate decreased with increasing calcination temperature. It was found that both the CH4 conversion rate and the surface area decreased with increasing calcination temperature. This suggests that crystal growth occurred with increasing calcination temperature, and the decrease in the Ni / CeO2 interface led to a decrease in the CH4 conversion rate.

Claims

1. Ni / CeO by sol-gel method ２ A method for manufacturing a catalyst, (1) A step of preparing a precursor by heating a solution containing Ni and Ce components. Step (2) involves calcining the precursor obtained in step (1) at 400°C to 900°C. A manufacturing method that includes this.

2. The manufacturing method according to claim 1, wherein the Ni component includes a nickel salt.

3. The manufacturing method according to claim 1, wherein the Ni component comprises nickel nitrate, nickel acetate, nickel chloride, nickel sulfate, nickel oxalate, nickel bromide, nickel carbonate, or a combination thereof.

4. The manufacturing method according to claim 1, wherein the Ce component includes a cerium salt.

5. The manufacturing method according to claim 1, wherein the Ce component comprises cerium nitrate, cerium acetate, cerium chloride, cerium sulfate, cerium oxalate, cerium perchlorate, or a combination thereof.

6. The manufacturing method according to claim 1, wherein the sol-gel method is the citric acid method.

7. The manufacturing method according to claim 1, wherein the solution further comprises ethylene glycol.

8. The manufacturing method according to claim 1, wherein the firing temperature in step (2) is 500°C to 800°C.

9. The obtained Ni / CeO ２ The manufacturing method according to claim 1, wherein the Ni content in the catalyst is 5 to 20 wt%.

10. The obtained Ni / CeO ２ CeO in catalysts ２ The manufacturing method according to claim 1, wherein the content of is 50 to 95 wt%.

11. After step (2), the Ni / CeO obtained in step (2) ２ The manufacturing method according to claim 1, comprising a step (3) of reducing the catalyst.

12. Ni / CeO obtained by the manufacturing method described in any one of claims 1 to 11 ２ CO ２ Gas and H ２ A method for producing methane, including a step (4) of circulating gas.

13. CeO ２ A catalyst containing CeO and Ni, having a surface area of 50 m ２ / g or more, the Ni / CeO ２ catalyst.

14. The Ni / CeO2 according to claim 13, wherein the Ni content is 5 to 20 wt%. ２ catalyst.

15. CEO ２ The Ni / CeO according to claim 13, wherein the content is 50 to 95 wt%. ２ catalyst.

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