Honeycomb catalyst for methanation reaction and method for producing the same

Abstract

To provide a honeycomb catalyst for methanation reaction, which is less likely to become excessively hot even under high gas flow rates, thereby facilitating adjustment of external cooling by a coolant and improving methane conversion efficiency.SOLUTION: A honeycomb catalyst for methanation reaction comprises: a honeycomb ceramic substrate in which multiple flow passage holes are delimited by porous partition walls; and a catalytic component comprising an active metal with catalytic activity and a catalyst carrier that supports the active metal on the partition walls, where the catalyst has a BET specific surface area per unit volume of 8700 m2 / L or more.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a honeycomb-type methanation reaction catalyst for producing methane gas from carbon dioxide gas or a mixed gas containing carbon monoxide gas and hydrogen gas, and a method for producing the same. [Background technology]

[0002] Methanation technology, which synthesizes methane (CH4) from carbon dioxide (CO2) or carbon monoxide (CO) and hydrogen (H2), has attracted attention as one of the technologies to reduce greenhouse gases. The methanation reaction is a catalytic reaction, and Ni-based catalysts and Ru-based catalysts supported on porous oxides such as alumina, ceria, and zirconia are known to have such catalytic activity. Catalysts for methanation reactions are used in various shapes, but granular catalysts are generally packed into a reaction tube.

[0003] However, the methanation reaction generates a large amount of heat, and because the higher the reaction temperature, the lower the methane conversion rate due to chemical equilibrium, so heat management to keep the catalyst temperature within an appropriate temperature range is important. However, in the reaction tubes using the above-mentioned granular catalyst, extremely high-temperature hot spots are likely to occur, and when hot spots occur, the methane conversion rate decreases due to catalyst deterioration or thermal runaway. In order to solve this problem, research is being conducted on honeycomb-type catalysts in which catalyst powder is coated on a honeycomb-structured ceramic substrate, as shown in Patent Document 1.

[0004] Patent Document 1 discloses a method for producing a honeycomb catalyst for carbon monoxide methanation, characterized by forming a catalyst layer made of metal and metal oxide on a honeycomb substrate made of metal or ceramic. By using the honeycomb catalyst described in Patent Document 1, when converting carbon monoxide in hydrogen-containing gas to useful methane, a large pressure difference or the like does not occur even at a high superficial velocity, and the reaction temperature does not rise rapidly due to a runaway reaction, which causes catalyst deterioration, and temperature control in the system is easy. It is described that this makes it possible to realize an ideal mechanism for removing carbon monoxide from hydrogen-containing gas stably and efficiently. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-252991 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, while the conventionally known honeycomb structured methanation catalyst as shown in Patent Document 1 has improved heat management compared to conventionally known granular methanation catalysts, the reaction heat generated at high gas flow rates is large, and there is a risk of problems such as catalyst deterioration and a decrease in methane conversion rate due to thermal runaway. Therefore, it has been common to use it as an isothermal reaction tube in which the catalyst reaction tube is cooled from the outside with a refrigerant to adjust the temperature.

[0007] In order to solve the above problems, the present invention aims to provide a honeycomb-type methanation reaction catalyst which is less likely to become hot even at high gas flow rates, and therefore allows easy adjustment of external cooling with a refrigerant, thereby improving methane conversion. [Means for solving the problem]

[0008] The first embodiment of the present invention comprises a honeycomb-type ceramic substrate having a plurality of flow holes defined by porous partition walls, and a catalyst component comprising an active metal having catalytic activity and a catalyst carrier carrying the active metal on the partition walls, the catalyst component having a BET specific surface area per volume of 8700 m 2 / L or more.

[0009] In this case, it is preferable that the amount of the catalyst support is 55 g / L or more, and the proportion of the active metal in the mass of the catalyst component is 18 mass % or more and 35 mass % or less.

[0010] A second embodiment of the present invention is a method for producing a honeycomb-type methanation reaction catalyst, comprising: a first step of preparing a honeycomb substrate carrying a catalyst carrier by allowing a honeycomb-type ceramic substrate having a plurality of flow holes defined by porous partition walls to absorb a colloidal aqueous solution, drying the colloidal aqueous solution, and supporting a catalyst carrier on an inner surface of the honeycomb-type ceramic substrate; a second step of preparing a honeycomb substrate carrying a catalyst precursor by allowing the catalyst carrier to absorb an aqueous solution of an active metal salt having catalytic activity, drying the aqueous solution of the active metal salt, and supporting a metal salt of the active metal on the catalyst carrier; and a third step of firing the honeycomb substrate carrying the catalyst precursor and reducing it under a reducing gas atmosphere to obtain a honeycomb-type methanation reaction catalyst. Effect of the Invention

[0011] According to the present invention, it is possible to provide a honeycomb-type methanation reaction catalyst which is unlikely to become hot even at a high gas flow rate, and therefore allows easy adjustment of external cooling with a refrigerant, thereby improving methane conversion. [Brief description of the drawings]

[0012] [Figure 1](a) A schematic diagram showing a cross section perpendicular to the longitudinal direction of the honeycomb-type methanation reaction catalyst according to the present invention. (b) A schematic diagram showing a cross section parallel to the longitudinal direction of the honeycomb-type methanation reaction catalyst according to the present invention. (c) An enlarged view of a flow hole and a partition wall of the honeycomb-type methanation reaction catalyst according to the present invention. (d) A schematic diagram showing a structure of a partition wall of the honeycomb-type methanation reaction catalyst according to the present invention. (e) A schematic diagram showing a state of a catalyst supported in the form of partition walls of the honeycomb-type methanation reaction catalyst according to the present invention. [Diagram 2] FIG. 1 is a flow diagram showing an example of a method for producing a honeycomb-type methanation reaction catalyst according to the present invention. [Diagram 3] FIG. 2 is a graph showing the relationship between the BET specific surface area per catalyst volume of the honeycomb-type methanation reaction catalyst according to the present invention and the methane conversion rate. [Figure 4] FIG. 2 is a diagram showing the relationship between the BET specific surface area per catalyst volume and the catalyst temperature of the honeycomb-type methanation reaction catalyst according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present inventors conducted extensive research into ways to improve the methane conversion rate in methanation reaction catalysts having the conventional honeycomb structure form and to prevent thermal runaway caused by exothermic reactions, and discovered a honeycomb-type methanation reaction catalyst with an increased BET specific surface area per volume, leading to the invention.

[0014] Hereinafter, an embodiment of the present invention will be described. First, a honeycomb-type methanation reaction catalyst will be described with reference to Fig. 1, and then a manufacturing method for obtaining the honeycomb-type methanation reaction catalyst will be described. However, the present invention is not limited to the embodiment described here, and appropriate combinations and improvements are possible within the scope of the technical idea of ​​the invention.

[0015] <Honeycomb-type methanation catalyst> The honeycomb-type methanation reaction catalyst of the present invention (hereinafter, also simply referred to as honeycomb catalyst) comprises a honeycomb-type ceramic substrate having a plurality of flow holes defined by partition walls, a catalytic component comprising an active metal having catalytic activity and a catalyst carrier carrying the active metal on the partition walls, and has a BET specific surface area per volume of 8700 m 2 / L or more.

[0016] An example of the configuration of a honeycomb-type methanation reaction catalyst is shown in Figure 1. A honeycomb catalyst 100 is configured by supporting a catalyst component 120 on a honeycomb-type ceramic substrate (hereinafter referred to as honeycomb substrate) 110.

[0017] The honeycomb substrate 110 has partition walls 111 and a plurality of through holes 112 defined by the partition walls 111. The plurality of through holes 112 adjacent to each other across the partition walls 111 penetrate the honeycomb substrate from one end face to the other end face in parallel with each other, and can pass a raw material gas containing a mixture of a gas containing carbon dioxide or carbon monoxide and hydrogen. In addition, a catalyst component 120 is supported on the surface of the partition walls 111, and a methanation reaction occurs when the raw material gas comes into contact with the catalyst component 120. In addition, the partition walls 111 are porous, and the pores 113 communicate with the partition walls 111. This increases the opportunity for the raw material gas to come into contact with the catalyst component 120 supported on the partition walls 111, thereby improving the methane conversion rate.

[0018] The material of the honeycomb substrate 110 is not particularly limited as long as it is a material that can form the partition walls 111 into a porous body. For this reason, for example, a sintered body such as cordierite, silicon carbide, or a composite of these can be suitably used.

[0019] 1 has a cylindrical shape, but is not limited to this shape and may be, for example, a substantially polygonal prism shape. The size of the honeycomb substrate 110 is also not particularly limited and can be appropriately determined depending on the size of the reaction tube in which the honeycomb catalyst 100 is installed.

[0020] 1 has a rectangular cross-sectional shape perpendicular to the penetrating direction, but the shape is not limited thereto and may be, for example, a substantially polygonal or substantially circular shape. In addition, the density of the through holes 112 in the honeycomb substrate 110 is not particularly limited.

[0021] The catalyst component 120 is composed of an active metal 121 and a catalyst carrier 122 for supporting the active metal 121 on the partition wall 111. The active metal 121 desirably has high activity for methanation of carbon dioxide or carbon monoxide, and preferably contains at least one of Ni, Fe, Co, Cu, and Ru. The catalyst carrier 122 is supported in the form of a film on the partition wall 111, and the film formed by the catalyst carrier 122 has pores for supporting the active metal 121. Such a catalyst carrier 122 is preferably made of ceramics, and more preferably contains at least one of alumina (Al2O3), ceria (CeO2), and zirconia (ZrO2).

[0022] Furthermore, the higher the specific surface area of ​​the catalyst component 120, the lower the activation temperature, and the lower the electric furnace temperature at which the methanation reaction starts. As a result, the catalyst temperature during the reaction can be lowered. Therefore, in order to avoid thermal runaway, it is desirable to have a sufficient specific surface area so that the catalyst temperature during the methanation reaction is 400°C or less. Therefore, the lower limit of the BET specific surface area per volume of the honeycomb catalyst 100 is 8700 m. 2 / L. The upper limit of the BET specific surface area per volume of the honeycomb catalyst 100 is not particularly limited, but as shown in Figs. 3 and 4, the larger the BET specific surface area per volume of the honeycomb catalyst 100, the more the effect on the methane conversion rate and catalyst temperature decreases, and the catalyst component 120 supported on the partition wall 111 becomes less effectively utilized. Therefore, the BET specific surface area per volume of the honeycomb catalyst 100 is set to 150,000 m 2 / L or less, and more preferably 30,000m 2 / L or less, and more preferably 25,000 m 2The volume of the honeycomb catalyst 100 is less than πR / L, which is made up of the partition walls 111, the through holes 112, and the catalyst components 120. For example, if the honeycomb catalyst 100 has a cylindrical shape, the volume of the honeycomb catalyst 100 is calculated by using the outer diameter R and the height H. 2 H / 4. By setting the specific surface area in this way, a methane conversion rate (CH4 amount [mol] / CO2 amount [mol]) of more than 80% can be ensured, and the temperature of the honeycomb catalyst 100 during the methanation reaction can be kept below 400°C even at high gas flow rates, preventing the occurrence of thermal runaway. In addition, since the honeycomb catalyst 100 is less likely to become hot, cooling control can be easily performed to keep the temperature below the temperature at which the methanation activity of the active metal 121 is deactivated. A method for measuring such a specific surface area will be described later.

[0023] In order to ensure such a specific surface area of ​​the honeycomb catalyst 100, it is preferable that the ratio of the amount of the catalyst carrier 122 loaded to the volume of the honeycomb catalyst 100 is 55 g / L or more, and the ratio of the active metal 121 to the mass of the catalyst component 120 is 18 mass% or more and 35 mass% or less. The larger the amount and surface area of ​​the catalyst carrier 122 loaded, the more improved the CO2 adsorption performance is, and if it is too small, a sufficient methane conversion rate cannot be obtained, so it is preferable that the amount of the catalyst carrier 122 loaded is 55 g / L or more. Furthermore, if the ratio of the active metal 121 to the catalyst support 122 is too small, the amount of active metal 121 for converting CO2 to CH4 will be insufficient relative to the amount of CO2 adsorbed on the catalyst support 122, resulting in a decrease in the methane conversion rate. Therefore, it is preferable that the ratio of the active metal 121 is 18 mass% or more. On the other hand, if the ratio of the active metal 121 is too large, the amount of active metal 121 for converting CO2 to CH4 will be excessive relative to the amount of CO2 adsorbed on the catalyst support 122, and the amount of active metal 121 that is not effectively utilized will increase. Therefore, it is preferable that the ratio of the active metal 121 is 35 mass% or less.

[0024] <Manufacturing method of honeycomb-type methanation reaction catalyst> The method for producing a honeycomb-type methanation reaction catalyst of the present invention is characterized by comprising: a first step of preparing a honeycomb substrate carrying a catalyst carrier by allowing a honeycomb-type ceramic substrate having a plurality of flow holes defined by porous partition walls to absorb a colloidal aqueous solution, drying the colloidal aqueous solution, and supporting a catalyst carrier on the inner surface of the honeycomb-type ceramic substrate; a second step of preparing a honeycomb substrate carrying a catalyst precursor by allowing the catalyst carrier to absorb an aqueous solution of an active metal salt having catalytic activity, drying the aqueous solution of the metal salt of the active metal, and supporting the metal salt of the active metal on the catalyst carrier; and a third step of firing the honeycomb substrate carrying a catalyst precursor and then reducing the honeycomb substrate in a reducing gas atmosphere to obtain a honeycomb-type methanation reaction catalyst.

[0025] Fig. 2 shows a flow chart illustrating one embodiment of a manufacturing method for the honeycomb catalyst 100. The manufacturing method for the honeycomb catalyst 100 includes a first step of preparing a honeycomb substrate supporting a catalyst carrier, a second step of preparing a honeycomb substrate supporting a catalyst precursor, and a third step of obtaining a honeycomb-type methanation reaction catalyst.

[0026] First, in the first step of producing a catalyst support-supported honeycomb substrate, the honeycomb substrate 110 is immersed in a colloidal aqueous solution and then dried to obtain the catalyst support-supported honeycomb substrate.

[0027] The particle diameter of the raw material of the catalyst carrier 122 contained in the colloidal aqueous solution is less than 300 nm, preferably 100 nm or less, more preferably 10 nm to 100 nm, in order to increase the specific surface area. In this case, the components of the colloidal aqueous solution are not particularly limited, but it is more preferable to include at least one of alumina, ceria, and zirconia in consideration of the cost and the methanation activity of the catalyst carrier 122. In addition, after removing the honeycomb substrate 110 immersed in the colloidal aqueous solution, it is preferable to remove the colloidal aqueous solution accumulated in the flow holes 112 before drying. If not removed, the catalyst carrier 122 may be excessively supported, which may unintentionally hinder the inflow of the raw material gas.

[0028] Next, in the second step of preparing a catalyst precursor-supporting honeycomb substrate, the substrate is impregnated with an aqueous solution of an active metal salt having catalytic activity, and then dried to obtain a catalyst precursor-supporting honeycomb substrate.

[0029] In this case, since it is desirable for the active metal salt to have catalytic activity for the methanation reaction, it is preferable for the active metal salt to contain at least one of Ni, Fe, Co, Cu, and Ru. The type of catalytically active metal salt is not particularly limited, but for example, nitrates, acetates, etc. can be used.

[0030] Finally, in the third step of obtaining a honeycomb type methanation reaction catalyst, the catalyst precursor-supporting honeycomb substrate is fired and then reduced in a reducing gas atmosphere to obtain a honeycomb type methanation reaction catalyst.

[0031] The heat treatment atmosphere at this time is not limited as long as it can reduce the active metal salt, but it is preferable to use a gas atmosphere containing hydrogen and reduce the active metal salt by reacting with hydrogen to form an active metal. The heat treatment temperature is preferably 200°C to 580°C. If the temperature is less than 200°C, the reduction reaction may not be promoted, and it is preferable to perform the heat treatment at a temperature lower than the heat treatment temperature of the previous catalyst precursor preparation step, so it is preferable to perform the heat treatment at 580°C or less. The holding time of the heat treatment is preferably 0.5 to 5 hours. If it is less than 0.5 hours, the temperature may become uniform or the heating may be insufficient to completely finish the reduction reaction, and if it exceeds 5 hours, too much time and heat (electricity) for heating is required. EXAMPLES

[0032] In the following, examples are shown in which the amounts of catalyst carrier and active metal carried in the honeycomb catalyst are changed to confirm the relationship between the BET specific surface area per volume of the honeycomb catalyst and the methane conversion rate.

[0033] First, cordierite honeycomb substrates were prepared for use in the manufacture of Examples 1, 2, 3, 4, 5, and 6, which are examples of the honeycomb catalyst of the present invention, and Comparative Examples A, B, C, and D, which are comparative examples. The specific method is described below. A cordierite honeycomb having a cell density of 260 cpsi and a partition wall thickness of 305 μm was processed to a size of 20 mm in outer diameter and 50 mm in height using a hole saw with an inner diameter of φ20 mm to obtain 10 honeycomb substrates. In addition, the cordierite honeycomb substrate used in the manufacture of Example 7 was similarly processed to a size of 20 mm in outer diameter and 50 mm in height using a hole saw with an inner diameter of φ20 mm from a cordierite honeycomb having a cell density of 1200 cpsi and a partition wall thickness of 102 μm. In addition, the silicon carbide honeycomb substrate used in the production of Examples 8 and 9 was a silicon carbide honeycomb with a cell density of 300 cpsi and a partition wall thickness of 203 μm, which was similarly machined using a hole saw with an inner diameter φ=20 mm to a size of outer diameter R=20 mm and height H=50 mm.

[0034] Next, the obtained honeycomb substrate was immersed in a colloidal aqueous solution, and then dried to obtain a honeycomb substrate carrying a catalyst carrier. The specific method is as follows. Alumina (Al2O3) was selected as the catalyst carrier, and immersed in an alumina sol stock solution containing granular alumina nanoparticles of the order of 10 to 100 nm. The excess alumina sol was removed by compressed air, and then dried in a microwave dryer. This process was repeated for each of Examples 1 to 9 and Comparative Examples A to B until the target amount of carrier was reached, to obtain honeycomb substrates 1 to 9 and A to B carrying a catalyst carrier corresponding to Examples 1 to 9 and Comparative Examples A to B. The amount of catalyst carrier carried is as shown in Table 1. In Comparative Example C, an alumina solution containing granular alumina particles of the order of 0.3 to 6.0 μm was used. In Comparative Example D, the amount of catalyst carrier carried was 0.0 g / L, so this process was not performed.

[0035] Next, an active metal salt was supported on the catalyst carrier-supported honeycomb substrate to obtain a catalyst precursor-supported material. The specific method is described below. Nickel (Ni) was selected as the active metal, and the mass of nickel (II) nitrate hexahydrate was calculated and weighed so as to obtain the target Ni-supported amount for each of the honeycomb substrates used to prepare the catalyst carrier-supported honeycomb substrates 1 to 9 and A to C and Comparative Example D. Water was added to the weighed nickel (II) nitrate hexahydrate to prepare an aqueous nickel nitrate solution, and the catalyst carrier-supported honeycomb substrates 1 to 9 and A to C and Comparative Example D were impregnated with the entire amount of the aqueous solution having the corresponding amount of nickel nitrate, and then dried to obtain catalyst precursor-supported materials 1 to 9 and A to D corresponding to Examples 1 to 9 and Comparative Examples A to D.

[0036] Finally, the active metal salt in the catalyst precursor support was reduced to obtain a honeycomb catalyst. The specific method is described below. The catalyst precursor supports 1 to 9 and A to D were inserted into a SUS reaction tube with an inner diameter of φ20.5 mm, and the reaction tube was placed in an electric furnace. While introducing a mixed gas with a molar ratio of H2:Ar=1:4 into the reaction tube at a flow rate of 1.5 NL / min, heat treatment was performed at 500°C for 2 hours to obtain Examples 1 to 9 and Comparative Examples A to D. Then, the mixture was cooled once.

[0037] [Table 1]

[0038] <Methane conversion rate measurement> For Examples 1 to 9 and Comparative Examples A to D prepared in this manner, the methane conversion rate was measured. The specific method is shown below. After Examples 1 to 9 and Comparative Examples A to D were obtained by reduction heat treatment, the electric furnace was once cooled, and then the temperature of the electric furnace was raised again to a predetermined temperature. Then, a raw material gas in which CO2 gas, H2 gas, and N2 gas were mixed so that the molar ratio of the reaction gas was CO2:H2:N2 = 1:4:5 was introduced into the reaction tube at an empty tower velocity of 5000 h-1. By measuring the gas flow rate and analyzing the gas composition on the outlet side of the reaction tube, the methane conversion rate, which is the ratio of CO2 converted to CH4, was calculated. The set temperature of the electric furnace at this time was the temperature at which the methane conversion rate was the highest, which was measured in advance in the same manner for each of Examples 1 to 9 and Comparative Examples A to D. Also, the temperature at the center between the end face on the raw material gas inflow side and the end face on the raw material gas outflow side of Examples 1 to 9 and Comparative Examples A to D in the reaction tube (hereinafter referred to as the catalyst temperature) was actually measured as the average temperature during the methanation reaction by inserting a thermocouple 25 mm inside the center of the end face of the catalyst sample.

[0039] Table 1 shows various measurement results for Examples 1 to 9 and Comparative Examples A to D. In Examples 1 to 9, a methane conversion rate of 80% or more was obtained under the condition that the catalyst temperature was 400 °C or lower, showing good performance as a catalyst for the methanation reaction. On the other hand, for Comparative Examples A, C, and D, the methane conversion rate was less than 80% in all cases, and all of Comparative Examples A to D were obtained under the condition that the catalyst temperature exceeded 400 °C.

[0040] <BET Specific Surface Area Measurement> Also, in order to examine the relationship between the methane conversion rate and the BET specific surface area in the honeycomb catalyst, the BET specific surface area per unit volume of the honeycomb catalyst in Examples 1 to 9 and Comparative Examples A to D was measured. The specific method is shown below.

[0041] The catalyst precursor-supported materials of Examples 1 to 9 and Comparative Examples A to D were cut into pieces of about 0.2 to 0.4 g using a saw blade to prepare samples for BET specific surface area measurement. Mountech's Macsorb HM Model-1201 was used for the BET specific surface area measurement. The samples for BET specific surface area measurement were placed in a glass cell and pretreated in a nitrogen gas atmosphere at 200°C for 30 minutes using a preheater. Next, nitrogen was adsorbed at 77K (-196°C) to measure the BET specific surface area. The BET specific surface area is measured as the surface area per unit weight [m2 / g], but the catalyst samples used for methane conversion measurement have different sample weights because the catalyst carrier loading amount and active component loading amount are different. To normalize the weight difference, the weight of each sample was multiplied by the volume of each sample (=πR 2 The specific gravity of the sample [g / L] was divided by the specific gravity (H / 4) and multiplied to calculate the surface area per volume [m2 / L].

[0042] Figure 3 shows the relationship between the BET specific surface area per honeycomb catalyst volume and the methane conversion rate for each sample. Below, Examples 1 to 7 and Comparative Examples A to D, which used a cordierite honeycomb substrate, are plotted with circles, and Examples 8 and 9, which used a SiC honeycomb substrate, are plotted with triangles. As Figure 3 shows, the larger the BET specific surface area per honeycomb catalyst volume, the higher the methane conversion rate. Naturally, the higher the methane conversion rate, the higher the performance of the catalyst, and it is possible to obtain high-purity methane with fewer reaction times. Furthermore, in order to obtain a methane conversion rate of 80% or more, the BET specific surface area per honeycomb catalyst volume must be 8700 m 2 / L or more is desirable. Comparing Examples 1 and 7, it can be seen that even if the opening or partition wall thickness of the honeycomb substrate changes, if the amount of catalyst carrier and active component supported is the same, the BET specific surface area per honeycomb catalyst volume hardly changes. This is because the specific surface area of ​​the honeycomb substrate is negligibly small compared to the specific surface areas of the catalyst carrier and active component. When only the honeycomb substrate not supporting the catalyst carrier and active component is subjected to measurement, the BET specific surface area is below the detection limit. Therefore, it can be said that the BET specific surface area per honeycomb catalyst volume obtained by BET specific surface area measurement is contributed only by the catalyst component consisting of the catalyst carrier and active metal supported on the honeycomb substrate. In addition, comparing Examples 1 and 8, and Examples 2 and 9, it can be seen that when the honeycomb substrate is changed from cordierite to silicon carbide, the methane conversion rate decreases by several percent even if the amounts of catalyst carrier and active component are the same and the BET specific surface area is the same. This suggests that the methanation performance is not determined only by the performance of the catalyst carrier and active component, but that some kind of interaction occurs between the catalyst carrier and active component and the substrate, which affects the methanation performance. There are no particular limitations on the material of the substrate, but it can be seen that cordierite is more preferable.

[0043] The reason why the methane conversion rate increases as the BET specific surface area per volume of the honeycomb catalyst increases as described above is considered. Figure 4 shows the relationship between the BET specific surface area per volume and the catalyst temperature. As shown in Figure 4, the larger the BET specific surface area per volume of the honeycomb catalyst, the lower the activation temperature of the catalyst. As a result, the methanation reaction can be performed even if the electric furnace set temperature is lowered, so that the catalyst temperature during the reaction can be lowered and the methane conversion rate can be improved. From the above, it was found that the catalyst is unlikely to become hot even at a high gas flow rate, and therefore it is easy to adjust the external cooling by the refrigerant, and that it is effective to increase the BET specific surface area per volume of the honeycomb catalyst for the honeycomb type methanation reaction catalyst that improves the methane conversion rate. In addition, when comparing the catalyst temperatures of Examples 1 and 8 and Examples 2 and 9, it can be seen that the catalyst temperature is lower by several tens of degrees Celsius in Examples 8 and 9 using silicon carbide as the base material, even though the catalyst carrier and the amount of active component supported are the same and the BET specific surface area is the same. This is believed to be because the thermal conductivity of silicon carbide is several tens to several hundreds times higher than that of cordierite, and therefore the reaction heat from the methanation reaction can be removed more efficiently. However, as described above, Examples 1 and 2, which used a cordierite substrate, had a methane conversion rate several percent higher, and it is clear that cordierite is a more preferable substrate material. [Explanation of symbols]

[0044] 100: Honeycomb catalyst (honeycomb type catalyst for methanation reaction) 110: Honeycomb substrate (honeycomb-type ceramic substrate) 111: Bulkhead 112:Flow hole 120: Catalyst components 121:Active metal 122: Catalyst carrier

Claims

1. a honeycomb-type ceramic substrate having a plurality of flow holes defined by porous partition walls; A catalyst component comprising an active metal having catalytic activity and a catalyst carrier supporting the active metal on the partition wall. The BET specific surface area per volume is 8700 m ２ / L or more A honeycomb-type methanation reaction catalyst comprising:

2. The ratio of the amount of the catalyst carrier to the volume of the honeycomb-type methanation reaction catalyst is 55 g / L or more; The ratio of the active metal to the mass of the catalyst component layer is 18% by mass or more and 35% by mass or less. The honeycomb type methanation reaction catalyst according to claim 1,

3. a first step of making a honeycomb substrate carrying a catalyst carrier by absorbing a colloidal aqueous solution of a catalyst carrier having a particle size of less than 300 nm into a honeycomb ceramic substrate having a plurality of flow holes defined by porous partition walls, and then drying the colloidal aqueous solution to carry the catalyst carrier on an inner surface of the honeycomb ceramic substrate; a second step of preparing a honeycomb substrate carrying a catalyst precursor by absorbing an aqueous solution of an active metal salt into the catalyst support and then drying the aqueous solution of the active metal salt to support the active metal salt on the catalyst support; A third step of firing the catalyst precursor-supporting honeycomb substrate and then reducing the same in a reducing gas atmosphere to obtain a honeycomb-type methanation reaction catalyst; A method for producing a honeycomb-type methanation reaction catalyst, comprising:

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