Carbon dioxide storage and reduction catalyst
A CO2 storage and reduction catalyst with a porous metal oxide carrier and combined alkaline earth and alkali metal oxides addresses low absorption capacity and purity issues, achieving enhanced CO2 storage and methane production efficiency.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- KK TOYOTA CHUO KENKYUSHO
- Filing Date
- 2022-03-25
- Publication Date
- 2026-06-11
AI Technical Summary
Existing CO2 absorption and reduction catalysts using calcium oxide (CaO) or sodium oxide (Na2O) as CO2 absorbents suffer from low CO2 absorption capacity and purity issues due to gas impurities during switching between absorption and reduction steps, necessitating frequent regeneration and reducing methane gas purity.
A CO2 storage and reduction catalyst comprising a porous metal oxide carrier with ruthenium (Ru) support and a combination of alkaline earth metal oxides (e.g., calcium oxide) and alkali metal oxides (e.g., sodium oxide) in a specific mass ratio, enhancing CO2 absorption and utilization rates.
The catalyst significantly increases CO2 storage capacity and utilization rate, improving the efficiency of CO2 absorption and methanation reaction performance by leveraging the synergistic effect of alkaline earth and alkali metal oxides.
Smart Images
Figure 0007873092000001 
Figure 0007873092000002 
Figure 0007873092000003
Abstract
Description
Technical Field
[0001] The present invention relates to a carbon dioxide (CO2) absorption and reduction type catalyst.
Background Art
[0002] The methanation reaction using carbon dioxide (CO2) as a raw material has attracted attention in recent years from the perspective of reducing CO2 emissions for suppressing global warming. As catalysts used in such methanation reactions, a CO2 absorption and reduction type catalyst in which calcium oxide (CaO) as a CO2 absorbent and ruthenium (Ru) as a methanation catalyst are supported on a carrier such as alumina (for example, Japanese Patent Application Laid-Open No. 2020-110769 (Patent Document 1) and A. Bermejo-Lopez et al., Applied Catalysis B: Environmental, 2019, Vol. 256, 117845 (Non-Patent Document 1)), and a CO2 absorption and reduction type catalyst in which sodium oxide (Na2O) as a CO2 absorbent and ruthenium (Ru) as a methanation catalyst are supported on a carrier such as alumina (for example, A. Bermejo-Lopez et al., Applied Catalysis B: Environmental, 2019, Vol. 256, 117845 (Non-Patent Document 1)) are known. Such a CO2 absorption and reduction type catalyst absorbs CO2 by flowing a gas containing CO2, and reduces the absorbed CO2 by flowing a reducing gas (for example, H2) to produce methane (CH4).
[0003] However, when CaO is used as the CO2 absorbent, since the CO2 absorption amount is small, it is necessary to frequently repeat the CO2 absorption and the reduction by the reducing gas, and gas components other than CO2 (N2, O2, etc.) are likely to be mixed when switching between the CO2 absorption step and the reduction step by the reducing gas, and there is a problem that the purity of the obtained CH4 gas decreases.
[0004] Further, when Na2O is used as the CO2 absorbent, although the CO2 absorption amount increases compared to the case of using CaO, it is not always sufficient, and there are the same problems as in the case of CaO. [Prior art documents] [Patent Documents]
[0005] [Patent Document 1] Japanese Patent Publication No. 2020-110769 [Non-patent literature]
[0006] [Non-Patent Document 1] A. Bermejo-Lopez et al., Applied Catalysis B: Environmental, 2019, Vol. 256, pp. 117845. [Overview of the Initiative] [Problems that the invention aims to solve]
[0007] The present invention has been made in view of the problems of the above-mentioned prior art, and aims to provide a CO2 storage and reduction type catalyst with increased CO2 storage capacity. [Means for solving the problem]
[0008] As a result of diligent research to achieve the above objective, the inventors of this invention discovered that by using alkaline earth metal oxides and alkali metal oxides together as CO2 storage materials, the amount of CO2 absorbed increases compared to when each is used alone, thus completing the present invention.
[0009] In other words, the CO2 storage and reduction catalyst of the present invention contains a porous carrier made of a metal oxide, ruthenium supported on the porous carrier, and alkaline earth metal oxides and alkali metal oxides supported on the porous carrier. The alkaline earth metal oxide is calcium oxide, and the alkali metal oxide is sodium oxide. The present invention is characterized in that the mass ratio of the alkaline earth metal oxide to the alkali metal oxide is alkaline earth metal oxide:alkali metal oxide = 10:1 to 10:5.
[0010] In the CO2 storage reduction catalyst of the present invention, the total content of the alkaline earth metal oxide and the alkali metal oxide is preferably 11 to 15 parts by mass per 100 parts by mass of the total content of the porous carrier and ruthenium, and the ruthenium content is preferably 1 to 5 parts by mass per 100 parts by mass of the total content of the porous carrier and ruthenium. [Effects of the Invention]
[0012] According to the present invention, it is possible to obtain a CO2 storage reduction type catalyst that increases CO2 storage capacity and has a high utilization rate as a CO2 storage material. [Brief explanation of the drawing]
[0013] [Figure 1] This graph shows the CO2 storage capacity of the catalysts obtained in Example 4 and Comparative Examples 1-2. [Figure 2] This graph shows the CO2 storage capacity of the catalysts obtained in Examples 1-5 and Comparative Examples 3-5. [Figure 3] This graph shows the CO2 storage utilization rate of the catalysts obtained in Example 4 and Comparative Examples 1-2. [Figure 4] This graph shows the CO2 storage utilization rate of the catalysts obtained in Examples 1-5 and Comparative Examples 3-5. [Modes for carrying out the invention]
[0014] The present invention will be described in detail below with reference to its preferred embodiments.
[0015] [CO2 storage and reduction type catalyst] The carbon dioxide (CO2) storage and reduction catalyst of the present invention contains a porous carrier made of a metal oxide, ruthenium supported on the porous carrier, and alkaline earth metal oxides and alkali metal oxides supported on the porous carrier.
[0016] The carrier used in the present invention is a porous carrier made of a metal oxide. By using a porous carrier, gas components can diffuse well, improving the CO2 storage performance and the methanation reaction efficiency. The metal oxide is not particularly limited as long as it can be used as a carrier for a CO2 storage reduction type catalyst. Examples thereof include known metal oxides such as alumina (Al2O3), silica (SiO2), zirconia (ZrO2), and titania (TiO2). Among these metal oxides, alumina and titania are preferred, and alumina is more preferred, from the viewpoint of enhancing the methanation catalyst activity. Further, such metal oxides may be used alone or in combination of two or more.
[0017] The average pore diameter of the porous carrier is preferably 3 to 50 nm, more preferably 5 to 20 nm. When the average pore diameter of the porous carrier is less than the lower limit, gas components cannot diffuse sufficiently, and the CO2 storage performance and the methanation reaction efficiency tend to decrease. On the other hand, when it exceeds the upper limit, the stability of the pore structure tends to decrease.
[0018] Also, the pore volume of the porous carrier is preferably 0.3 to 1.5 cm 3 / g, more preferably 0.3 to 1.0 cm 3 / g. When the pore volume of the porous carrier is less than the lower limit, gas components cannot diffuse sufficiently, and the CO2 storage performance and the methanation reaction efficiency tend to decrease. On the other hand, when it exceeds the upper limit, the thermal stability of the porous carrier tends to decrease.
[0019] In the CO2 storage reduction type catalyst of the present invention, ruthenium (Ru) is supported on the porous carrier. This Ru acts as a methanation catalyst. Specifically, it promotes the reduction reaction of CO2 when CO2 stored in the CO2 storage material reacts with a reducing gas (e.g., H2) and is reduced to produce methane (CH4).
[0020] In the CO2 storage and reduction catalyst of the present invention, the Ru content is preferably 1 to 5 parts by mass per 100 parts by mass of the total content of the porous support and Ru. When the Ru content is within the above range, the reduction reaction of CO2 is promoted and the methanation reaction efficiency is improved. On the other hand, when the Ru content is below the lower limit, the reduction reaction of CO2 is not sufficiently promoted and the methanation reaction efficiency tends to decrease. On the other hand, when it exceeds the upper limit, the pores of the porous support become blocked, reducing the amount of CO2 absorbed, or Ru particles grow and the methanation catalyst activity decreases, so the CO2 absorption performance and methanation reaction efficiency tend to decrease.
[0021] Furthermore, in the CO2 storage reduction catalyst of the present invention, alkaline earth metal oxides and alkali metal oxides are supported on the porous carrier. These alkaline earth metal oxides and alkali metal oxides act as CO2 storage materials, and by using them together, the amount of CO2 absorbed increases and the utilization rate as CO2 storage materials increases compared to when each is used alone, thereby improving CO2 storage performance and methanation reaction efficiency. This is thought to be due to the synergistic effect of the alkaline earth metal oxides and alkali metal oxides in the presence of each other.
[0022] Examples of the alkaline earth metal oxides include magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO). Among these, CaO is preferred because it further increases CO2 storage capacity and improves the utilization rate as a CO2 storage material, thereby further enhancing CO2 storage performance and methane reaction efficiency.
[0023] Examples of alkali metal oxides include lithium oxide (Li2O), sodium oxide (Na2O), potassium oxide (K2O), rubidium oxide (Rb2O), and cesium oxide (Cs2O). Among these, Na2O is preferred because it further increases CO2 storage capacity and improves the utilization rate as a CO2 storage material, thereby further enhancing CO2 storage performance and methane reaction efficiency.
[0024] In the CO2 storage reduction catalyst of the present invention, the mass ratio of the alkaline earth metal oxide to the alkali metal oxide must be alkaline earth metal oxide:alkali metal oxide = 10:1 to 10:5. When the mass ratio is within the above range, the amount of CO2 absorbed increases, and the utilization rate as a CO2 storage material increases, thereby improving the CO2 storage performance and the methanation reaction efficiency. On the other hand, if the mass ratio falls below the lower limit (i.e., if the proportion of alkali metal oxide is too low) or exceeds the upper limit (i.e., if the proportion of alkali metal oxide is too high), the amount of CO2 absorbed decreases, and the utilization rate as a CO2 storage material decreases, thus lowering the CO2 storage performance and the methanation reaction efficiency. Furthermore, from the viewpoint of further improving CO2 storage performance and methane reaction efficiency by further increasing CO2 storage capacity and further increasing the utilization rate as a CO2 storage material, the mass ratio is preferably alkaline earth metal oxide:alkali metal oxide = 10:3 to 10:5, more preferably alkaline earth metal oxide:alkali metal oxide = 10:3.5 to 10:5, and particularly preferably alkaline earth metal oxide:alkali metal oxide = 10:3.5 to 10:4.5.
[0025] Furthermore, in the CO2 storage reduction catalyst of the present invention, the total content of the alkaline earth metal oxide and the alkali metal oxide is preferably 11 to 15 parts by mass, more preferably 13 to 15 parts by mass, even more preferably 13.5 to 15 parts by mass, and particularly preferably 13.5 to 14.5 parts by mass, based on 100 parts by mass of the total content of the porous support and Ru. When the total content of the alkaline earth metal oxide and the alkali metal oxide is within the above range, the amount of CO2 absorbed increases further, and the utilization rate as a CO2 storage material increases further, thus further improving the CO2 storage performance and the methanation reaction efficiency. On the one hand, when the total content of alkaline earth metal oxides and alkali metal oxides falls below the lower limit, there are fewer CO2 storage sites, the amount of CO2 stored decreases, and the utilization rate as a CO2 storage material decreases, so the CO2 storage performance and methane reaction efficiency tend to decrease. On the other hand, when it exceeds the upper limit, the pores of the porous carrier become blocked, the amount of CO2 stored decreases, and the utilization rate as a CO2 storage material decreases, so the CO2 storage performance and methane reaction efficiency tend to decrease.
[0026] [Method for preparing CO2 storage reduction catalyst] The CO2 storage and reduction catalyst of the present invention can be prepared, for example, as follows. Specifically, an aqueous solution containing an alkaline earth metal salt and an alkali metal salt in a predetermined mass ratio is prepared, a predetermined amount of a porous carrier made of a metal oxide supporting Ru is added to this aqueous solution, and then the solution is dried and calcined to obtain a CO2 storage and reduction catalyst in which alkaline earth metal oxide, alkali metal oxide and Ru are supported on the porous carrier made of the metal oxide. Alternatively, an aqueous solution containing an alkaline earth metal salt and an alkali metal salt in a predetermined mass ratio is prepared, a predetermined amount of a porous carrier made of a metal oxide is added to this aqueous solution, and then the solution is dried and calcined to prepare a CO2 storage material in which alkaline earth metal oxide and alkali metal oxide are supported on the porous carrier made of the metal oxide, and then the CO2 storage material is added to an aqueous solution in which a predetermined amount of Ru salt is dissolved, and then the solution is dried and calcined to obtain a CO2 storage and reduction catalyst in which alkaline earth metal oxide, alkali metal oxide and Ru are supported on the porous carrier made of the metal oxide. Furthermore, a CO2 storage and reduction catalyst can be obtained by preparing an aqueous solution containing an alkaline earth metal salt, an alkali metal salt, and a Ru salt in a predetermined mass ratio, adding a predetermined amount of a porous support made of a metal oxide to this aqueous solution, and then drying and calcining it, thereby supporting the alkaline earth metal oxide, alkali metal oxide, and Ru on the porous support made of the metal oxide.
[0027] The firing conditions are not particularly limited as long as alkaline earth metal salts are converted to alkaline earth metal oxides, alkali metal salts to alkali metal oxides, and Ru salts to Ru. For example, the firing temperature is preferably 400 to 600°C, more preferably 450 to 550°C, and the firing time is preferably 1 to 5 hours, more preferably 2 to 4 hours.
[0028] Examples of the alkaline earth metal salts and alkali metal salts include nitrates, carbonates, and acetates of alkaline earth metals (Mg, Ca, Sr, Ba) and alkali metals (Li, Na, K, Rb, Cs). Examples of Ru salts include ruthenium nitrosylnitrate, ruthenium nitrate, ruthenium chloride, and ruthenium carbonyl.
[0029] [CO2 storage and reduction treatment] Such a CO2 storage and reduction catalyst of the present invention can be applied, for example, to the following CO2 storage and reduction treatment. That is, after a gas containing CO2 is brought into contact with the CO2 storage and reduction catalyst of the present invention to absorb CO2, a reducing gas (for example, H2) is brought into contact with the CO2-absorbed CO2 storage and reduction catalyst, thereby reducing the absorbed CO2 and generating CH4. [Examples]
[0030] The present invention will be described more specifically below based on examples and comparative examples, but the present invention is not limited to the following examples.
[0031] (Example 1) Sodium nitrate (NaNO3, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., catalog number: 192-02555) and calcium nitrate (Ca(NO3)2, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., catalog number: 039-00735) were dissolved in deionized water such that the mass ratio of CaO to Na2O in the resulting catalyst was CaO:Na2O=10:1. In the resulting aqueous solution, ruthenium-supported alumina powder (Ru / Al2O3, manufactured by N.E. Chemcat Corporation, catalog number: HYAc-5E N-Type, Ru content: 5% by mass, alumina content: 95% by mass, average pore size of alumina: 13 nm, pore volume of alumina: 0.38 cm³) was dissolved. 3The amount of ( / g) was added to the resulting catalyst so that the total content of CaO and Na2O in the resulting catalyst was 11 parts by mass per 100 parts by mass of the Ru / Al2O3 powder. The resulting dispersion was stirred for about 2 hours, then heated to 250°C and evaporated to dryness. The resulting dry material was dried at 110°C for 12 hours, and then calcined at 500°C for 3 hours. The resulting catalyst powder (approximately 6g) was subjected to a pressure of 1000 kg / cm². 2 After pressurizing for 1 minute, the mixture was crushed and classified using a sieve to obtain a catalyst powder with a diameter of 0.5 to 1.0 mm [CaO(10)Na2O(1) / Ru(5) / Al2O3(95)] in which CaO, Na2O, and Ru were supported on Al2O3.
[0032] (Example 2) Except for dissolving NaNO3 and Ca(NO3)2 in deionized water so that the mass ratio of CaO to Na2O in the resulting catalyst is CaO:Na2O=10:2, and adding Ru / Al2O3 powder so that the total content of CaO and Na2O in the resulting catalyst is 12 parts by mass per 100 parts by mass of Ru / Al2O3 powder, the same procedure as in Example 1 was followed to obtain a catalyst powder [CaO(10)Na2O(2) / Ru(5) / Al2O3(95)] with a diameter of 0.5 to 1.0 mm, in which CaO, Na2O, and Ru are supported on Al2O3.
[0033] (Example 3) Except for dissolving NaNO3 and Ca(NO3)2 in deionized water so that the mass ratio of CaO to Na2O in the resulting catalyst is CaO:Na2O=10:3, and adding Ru / Al2O3 powder so that the total content of CaO and Na2O in the resulting catalyst is 13 parts by mass per 100 parts by mass of Ru / Al2O3 powder, the same procedure as in Example 1 was followed to obtain a catalyst powder [CaO(10)Na2O(3) / Ru(5) / Al2O3(95)] with a diameter of 0.5 to 1.0 mm, in which CaO, Na2O, and Ru are supported on Al2O3.
[0034] (Example 4) Except for dissolving NaNO3 and Ca(NO3)2 in deionized water so that the mass ratio of CaO to Na2O in the resulting catalyst is CaO:Na2O=10:4, and adding Ru / Al2O3 powder so that the total content of CaO and Na2O in the resulting catalyst is 14 parts by mass per 100 parts by mass of Ru / Al2O3 powder, the same procedure as in Example 1 was followed to obtain a catalyst powder [CaO(10)Na2O(4) / Ru(5) / Al2O3(95)] with a diameter of 0.5 to 1.0 mm, in which CaO, Na2O, and Ru are supported on Al2O3.
[0035] (Example 5) Except for dissolving NaNO3 and Ca(NO3)2 in deionized water so that the mass ratio of CaO to Na2O in the resulting catalyst is CaO:Na2O=10:5, and adding Ru / Al2O3 powder so that the total content of CaO and Na2O in the resulting catalyst is 15 parts by mass per 100 parts by mass of Ru / Al2O3 powder, the same procedure as in Example 1 was followed to obtain a catalyst powder [CaO(10)Na2O(5) / Ru(5) / Al2O3(95)] with a diameter of 0.5 to 1.0 mm, in which CaO, Na2O, and Ru are supported on Al2O3.
[0036] (Comparative Example 1) Except for not using NaNO3, only Ca(NO3)2 was dissolved in deionized water, and the Ru / Al2O3 powder was added in the same manner as in Example 1, such that the CaO content in the resulting catalyst was 14 parts by mass per 100 parts by mass of the Ru / Al2O3 powder, to obtain a catalyst powder [CaO(14) / Ru(5) / Al2O3(95)] with a diameter of 0.5 to 1.0 mm, in which CaO and Ru were supported on Al2O3.
[0037] (Comparative Example 2) Except for dissolving only NaNO3 in deionized water without using Ca(NO3)2, and adding Ru / Al2O3 powder so that the Na2O content in the resulting catalyst was 14 parts by mass per 100 parts by mass of Ru / Al2O3 powder, a catalyst powder [Na2O(14) / Ru(5) / Al2O3(95)] with a diameter of 0.5 to 1.0 mm, in which Na2O and Ru are supported on Al2O3, was obtained in the same manner as in Example 1.
[0038] (Comparative Example 3) Without using Na2O, only Ca(NO3)2 was dissolved in ion-exchanged water, and the Ru / Al2O3 powder was added in the same manner as in Example 1 except that the content of CaO in the obtained catalyst was 10 parts by mass with respect to 100 parts by mass of the Ru / Al2O3 powder, to obtain a catalyst powder with a diameter of 0.5 to 1.0 mm in which CaO and Ru were supported on Al2O3 [CaO(10) / Ru(5) / Al2O3(95)].
[0039] (Comparative Example 4) NaNO3 and Ca(NO3)2 were dissolved in ion-exchanged water so that the mass ratio of CaO to Na2O in the obtained catalyst was CaO:Na2O = 10:0.5, and the Ru / Al2O3 powder was added in the same manner as in Example 1 except that the total content of CaO and Na2O in the obtained catalyst was 10.5 parts by mass with respect to 100 parts by mass of the Ru / Al2O3 powder, to obtain a catalyst powder with a diameter of 0.5 to 1.0 mm in which CaO, Na2O, and Ru were supported on Al2O3 [CaO(10)Na2O(0.5) / Ru(5) / Al2O3(95)].
[0040] (Comparative Example 5) NaNO3 and Ca(NO3)2 were dissolved in ion-exchanged water so that the mass ratio of CaO to Na2O in the obtained catalyst was CaO:Na2O = 10:10, and the Ru / Al2O3 powder was added in the same manner as in Example 1 except that the total content of CaO and Na2O in the obtained catalyst was 20 parts by mass with respect to 100 parts by mass of the Ru / Al2O3 powder, to obtain a catalyst powder with a diameter of 0.5 to 1.0 mm in which CaO, Na2O, and Ru were supported on Al2O3 [CaO(10)Na2O(10) / Ru(5) / Al2O3(95)].
[0041] <CO2 Storage Performance Evaluation> The obtained catalyst powder had a volume of 2.4 cm 3It was filled into a stainless steel (SUS) reaction tube (inner diameter: 8 mm) so as to be, and this reaction tube was attached to a temperature-programmed desorption analyzer (「TP-5000」manufactured by Hemmi Slide Rule Co., Ltd.). A CO2-containing gas of CO2 (10%) + He (the balance) was passed through at a catalyst-containing gas temperature of 320 °C and a flow rate of 40 ml / min for 15 minutes to occlude CO2 in the catalyst [CO2 occlusion step]. Then, a H2-containing gas of H2 (40%) + He (the balance) was passed through at a catalyst-containing gas temperature of 320 °C and a flow rate of 40 ml / min for 15 minutes to reduce the occluded CO2 in the catalyst to CH4 [H2 reduction step]. This series of steps [CO2 occlusion step → H2 reduction step] was repeated twice. In the second CO2 occlusion step, the amount of CO2 in the catalyst outlet gas was measured, and the CO2 occlusion amount was determined from the amount of CO2 in the catalyst inlet gas and the amount of CO2 in the catalyst outlet gas. The results are shown in FIGS. 1 and 2.
[0042] As shown in FIG. 1, when CaO and Na2O were used in combination as the CO2 occlusion material (Example 4), it was found that the CO2 occlusion amount was larger than that in the case of CaO alone (Comparative Example 1) and the case of Na2O alone (Comparative Example 2).
[0043] Also, as shown in FIG. 2, by adding Na2O to CaO at a predetermined ratio, it was found that the CO2 occlusion amount was larger than that in the case where Na2O was not added (Comparative Example 3), the case where the addition amount of Na2O was small (Comparative Example 4), or the case where the addition amount of Na2O was large (Comparative Example 5) (Examples 1 to 5).
[0044] <Calculation of CO2 occlusion material utilization rate> CaO and Na2O, which are CO2 occlusion materials, are represented by the following formulas: CaO + CO2 → CaCO3 Na2O + CO2 → Na2CO3 As shown, they occlude CO2 by reacting with CO2 to form CaCO3 and Na2CO3. As is clear from the above formulas, 1 mol of CaO and Na2O can each occlude 1 mol of CO2. Therefore, the following formulas: CaO utilization rate [%] = CO2 occlusion amount [mol] / CaO content [mol] × 100 Na2O utilization rate [%]=CO2 storage amount [mol] / Na2O content [mol]×100 As shown, the utilization rate of CaO and Na2O as CO2 storage materials is expressed as the ratio of CO2 storage amount to the CaO content and Na2O content in the catalyst [%], and the sum of these is the utilization rate of the catalyst as a CO2 storage material.
[0045] Therefore, the CO2 storage material utilization rate was calculated for the catalysts obtained in the examples and comparative examples using the above formula. The results are shown in Figures 3 and 4. As shown in Figure 3, it was found that when CaO and Na2O were used together as CO2 storage material (Example 4), the utilization rate as CO2 storage material was higher compared to when CaO was used alone (Comparative Example 1) and when Na2O was used alone (Comparative Example 2). Furthermore, as shown in Figure 4, it was found that adding Na2O to CaO in a predetermined ratio increased the utilization rate as CO2 storage material compared to when Na2O was not added (Comparative Example 3), when the amount of Na2O added was small (Comparative Example 4), or when the amount of Na2O added was large (Comparative Example 5) (Examples 1-5). This is thought to be because the coexistence of CaO and Na2O improved the utilization rate of each CO2 storage material compared to when they were used alone. [Industrial applicability]
[0046] As described above, according to the present invention, it is possible to obtain a CO2 storage and reduction type catalyst that increases CO2 storage capacity and has a high utilization rate as a CO2 storage material. Therefore, the CO2 storage and reduction type catalyst of the present invention is useful as a catalyst that can efficiently absorb CO2 and reduce it to CH4.
Claims
1. It contains a porous carrier made of a metal oxide, ruthenium supported on the porous carrier, and alkaline earth metal oxides and alkali metal oxides supported on the porous carrier. The alkaline earth metal oxide is calcium oxide, and the alkali metal oxide is sodium oxide. A carbon dioxide storage and reduction catalyst characterized in that the mass ratio of the alkaline earth metal oxide to the alkali metal oxide is alkaline earth metal oxide:alkali metal oxide = 10:1 to 10:
5.
2. The carbon dioxide storage and reduction catalyst according to claim 1, characterized in that the total content of the alkaline earth metal oxide and the alkali metal oxide is 11 to 15 parts by mass per 100 parts by mass of the total content of the porous carrier and ruthenium.
3. The carbon dioxide storage and reduction catalyst according to claim 1 or 2, characterized in that the ruthenium content is 1 to 5 parts by mass per 100 parts by mass of the total content of the porous carrier and ruthenium.