JP2022089552A - Catalyst for production of syngas and device for producing syngas - Google Patents

Abstract

To provide a catalyst for the production of syngas that can suppress formation of methane even in the temperature range of 400°C or lower and can improve the yield of carbon monoxide.SOLUTION: The inventive catalyst for the production of syngas is used to produce carbon monoxide by reacting carbon dioxide and hydrogen. The catalyst contains a catalyst metal containing platinum, and at least one selected from the group consisting of silver, copper, zinc, and gold.SELECTED DRAWING: Figure 2

Description

The present invention relates to a catalyst for producing synthetic gas and a synthetic gas producing apparatus used for producing carbon monoxide by reacting carbon dioxide with hydrogen.

In recent years, with the global economic development, carbon dioxide (CO ₂ ) emissions in industry, industry, agriculture, etc. have increased sharply. Especially in developed countries, there is an urgent need to curb carbon dioxide emissions. Among them, carbon dioxide emissions from power generation are extremely high, and it is necessary to switch to an energy system that does not increase carbon dioxide in the atmosphere. It has become. Furthermore, in energy systems, there are some fields such as aviation, ships, long-distance cargo, load adjustment power generation, iron making, cement, etc., which are difficult to deal with by electrification and carbon dioxide capture and storage (CCS). Is required not only to remove carbon dioxide emitted from power generation and the use of fuel, so-called "decarbonization", but also to "carbon cycle" to use carbon dioxide cyclically. One means of this carbon cycle is the recycling of carbon dioxide. Recycling carbon dioxide means converting carbon dioxide into fuel and chemical products for use. The technology for converting carbon dioxide into hydrocarbons for the purpose of recycling is a very important technology not only for reducing carbon dioxide emissions but also for preventing the emitted carbon dioxide from diffusing into the atmosphere.

Syngas, which is a mixed gas of carbon monoxide (CO) and hydrogen (H ₂ ), is industrially very important because it can be applied to various chemical products by producing hydrocarbons by the Fischer-Tropsch method. Therefore, in order to suppress carbon dioxide emissions, a method for producing carbon monoxide from carbon dioxide is being studied. Examples of the method for producing carbon monoxide from carbon dioxide include a method by a reverse shift reaction represented by the following reaction formula (1).

CO ₂ + H ₂ + 40.9kJ / mol → CO + H ₂ O (1)

However, since the reverse shift reaction is basically an endothermic reaction, it generally occurs at a high temperature of 700 ° C. or higher and requires a large amount of heat. Further, in the reverse shift reaction, it is necessary to secure a reaction vessel and heat insulating properties to withstand a high temperature of 700 ° C. or higher, so that the manufacturing cost is high. Further, since the industrial waste heat is mainly 700 ° C. or lower, the contribution of energy saving by utilizing the industrial waste heat is small in the reaction at a high temperature of 700 ° C. or higher.

Therefore, if carbon monoxide can be produced by causing a reverse shift reaction in a temperature range of 400 ° C. or lower, which is a temperature range of many unused waste heats, energy saving by utilizing waste heat and costs for reaction vessels and the like can be achieved. It is possible to significantly reduce the production cost of carbon monoxide by reducing the amount of carbon monoxide. On the other hand, the temperature region of 400 ° C. or lower is generally a temperature region in which the production of methane (CH ₄ ) is more advantageous than the production of carbon monoxide from carbon dioxide and hydrogen in the reverse shift reaction in terms of chemical equilibrium. be. Therefore, in the presence of carbon dioxide and hydrogen at 400 ° C. or lower, more methane is produced than carbon monoxide, which causes a problem that the yield of carbon monoxide is lowered.

The present invention has been made in view of the above problems, and is a catalyst for producing synthetic gas and a synthetic gas producing apparatus capable of suppressing the production of methane and improving the yield of carbon monoxide even in a temperature range of 400 ° C. or lower. The main purpose is to provide.

In order to solve the above problems, the catalyst for producing synthetic gas of the present invention is a catalyst for producing synthetic gas used for producing carbon monoxide by reacting carbon dioxide with hydrogen, and platinum and platinum are used. It is characterized by containing a catalytic metal containing at least one selected from the group consisting of silver, copper, zinc, and gold.

According to the catalyst for producing synthetic gas, the production of methane can be suppressed and the yield of carbon monoxide can be improved even in a temperature range of 400 ° C. or lower.

Further, in the synthetic gas production apparatus of the present invention, a catalyst metal containing platinum and at least one selected from the group consisting of silver, copper, zinc, and gold in a reaction vessel for reacting carbon dioxide and hydrogen is contained. It is characterized by comprising a catalyst for producing a synthetic gas containing the catalyst.

According to the above synthetic gas production apparatus, it is possible to suppress the production of methane and improve the yield of carbon monoxide even in the temperature range of 400 ° C. or lower.

According to the present invention, it is possible to suppress the production of methane and improve the yield of carbon monoxide even in the temperature range of 400 ° C. or lower.

Issues, configurations, and effects of the present invention other than those described above will be clarified by the following description of embodiments for carrying out the invention.

It is an X-ray-diffraction pattern of the crystal structure of the catalyst for syngas production obtained in Example 1. The content of silver or gold and the formation of carbon monoxide at 350 ° C. with respect to the total content of platinum (Pt) and silver (Ag) or gold (Au) in the synthetic gas production catalysts obtained in Examples and Comparative Examples. It is a graph which shows the relationship with the ratio (CH ₄ / CO) of the production amount (material amount) of methane to the amount (material amount). 3 is a graph showing the relationship between the content of silver or gold and the conversion rate of CO ₂ at 350 ° C. with respect to the total content of platinum and silver or gold in the catalysts for producing synthetic gas obtained in Examples and Comparative Examples.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings and the like. The following description shows specific examples of the contents of the present invention, and the present invention is not limited to these explanations, and is made by those skilled in the art within the scope of the technical ideas disclosed in the present specification. Various changes and modifications are possible. Further, in all the drawings for explaining the present invention, those having the same function may be designated by the same reference numerals, and the repeated description thereof may be omitted.

"-" Described in the present specification is used to mean that the numerical values described before and after it are included as the lower limit value and the upper limit value. In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value described in another stepwise. The upper or lower limit of the numerical range described herein may be replaced with the values shown in the examples.

When selecting a material from the material group exemplified below, the material may be selected alone or in combination of two or in combination within the range not inconsistent with the contents disclosed in the present specification. , Materials other than the material group exemplified below may be selected as long as they do not contradict the contents disclosed in the present specification.

<Catalyst for producing synthetic gas>
The catalyst for producing synthetic gas according to the embodiment is a catalyst for producing synthetic gas used for producing carbon monoxide (CO) by reacting carbon dioxide (CO ₂ ) with hydrogen (H ₂ ). , Platinum (Pt) and at least one selected from the group consisting of silver (Ag), copper (Cu), zinc (Zn), and gold (Au). It is a thing. In this synthetic gas production catalyst, the amount of methane produced can be reduced and the selectivity of carbon monoxide can be improved by adding metal elements such as silver, copper, zinc, and gold to the platinum catalyst. As a result, the production of methane can be suppressed and the yield of carbon monoxide can be improved even in the temperature range of 400 ° C. or lower.

The temperature region of 400 ° C. or lower is generally a temperature region in which methane production is more advantageous than carbon monoxide production from carbon dioxide and hydrogen in a reverse shift reaction in terms of chemical equilibrium. Therefore, in the presence of carbon dioxide and hydrogen at 400 ° C. or lower, more methane is produced than carbon monoxide, which causes a problem that the yield of carbon monoxide is lowered. The present inventors have found that platinum catalysts exhibit a higher carbon dioxide conversion rate than general copper catalysts in the temperature range of 400 ° C. or lower, and platinum catalysts contain methane as compared with general copper catalysts. It was clarified that a large amount of carbon monoxide was produced and the selectivity of carbon monoxide decreased. Then, as a result of diligent studies, the present inventors dramatically increased the amount of methane produced by adding metal elements such as silver, copper, zinc, and gold to the platinum catalyst. We have newly found that it can be reduced. The reduction in the amount of methane produced by the addition of these metal elements was due to the fact that the 5d electron orbitals of platinum were filled with these metal elements, and the dissociative adsorption of carbon dioxide or carbon monoxide adsorbed on the platinum surface was suppressed. It is considered that the cause is the reaction between the two phases of platinum and these metal elements, and the reaction between the three phases of platinum and these metal elements and the carrier described later.

The catalyst metal preferably contains the platinum and the silver. This is because the production of methane can be effectively suppressed and the yield of carbon monoxide can be significantly improved in the temperature range of 400 ° C. or lower. As the catalyst metal containing the platinum and the silver, the content of the silver with respect to the total content of the platinum and the silver in the catalyst metal is in the range of 1 atomic% or more and 25 atomic% or less. Those are preferable. This is because the production of methane can be suppressed particularly effectively when the silver content with respect to the total content of platinum and silver is 1 atomic% or more, and the silver content with respect to the total content of platinum and silver. This is because when the amount is 25 atomic% or less, the decrease in the conversion rate of carbon dioxide can be suppressed.

The catalyst for producing synthetic gas used for producing carbon monoxide by reacting carbon dioxide with hydrogen is at least one selected from the group consisting of platinum, silver, copper, zinc, and gold. Instead of the catalyst metal containing seeds, platinum, ruthenium (Ru), rhodium (Rh), palladium (Pd), nickel (Ni), iron (Fe), cobalt (Co), copper, zinc, iridium (Ir) ), Gold, and silver, even those containing a catalytic metal containing at least two selected from the group, suppress the production of methane even in the temperature range of 400 ° C. or lower, and the yield of carbon monoxide. There is something that can be improved. This is because the electron orbits of one metal element are filled with the other metal element, so that the dissociative adsorption of carbon dioxide or carbon monoxide adsorbed on the surface of the other metal element is suppressed. It is considered that the reaction between the two phases of the metal element and the reaction between the three phases of one metal element and the other metal element and the carrier described later is caused. Specific examples thereof include a catalyst for producing a synthetic gas containing a catalyst metal containing nickel and at least one selected from the group consisting of silver and copper. In this synthetic gas production catalyst, the nickel catalyst exhibits a higher carbon dioxide conversion rate than a general copper catalyst in the temperature range of 400 ° C. or lower, and the electron orbit of nickel is filled with silver, copper, etc. to make nickel. Since the dissociation and adsorption of carbon dioxide or carbon monoxide adsorbed on the surface is suppressed, the production of methane can be suppressed and the yield of carbon monoxide can be improved even in the temperature range of 400 ° C. or lower.

The catalyst for producing synthetic gas is not particularly limited as long as it contains a catalyst metal containing platinum and at least one selected from the group consisting of silver, copper, zinc, and gold, but further includes a carrier. It is preferable that the catalyst metal is supported on the carrier.

The material of the carrier is not particularly limited and may be appropriately selected from general carrier materials, and examples thereof include metal oxides and the like. Examples of the metal oxide include SiO ₂ , Al ₂ O ₃ , ZrO ₂ , TIO ₂ , MgO, cerium oxide (CeO ₂ ), La ₂ O ₃ , ZnO, GeO ₂ , SnO ₂ , V ₂ O ₅ , Y. Examples thereof include ₂ O ₃ , Nb ₂ O ₅ , MoO ₃ , WO ₃ , and zeolite. The carrier may contain one of these metal oxides alone, or may contain two or more of them. The carrier containing cerium oxide is preferable. This is because the specific surface area of the carrier becomes large.

The shape of the carrier is not particularly limited, and may be a general shape of the carrier, and examples thereof include granules such as spherical and columnar, and irregular shapes such as honeycomb. As the shape of the carrier, a granular one is usually preferably used.

The specific surface area of the carrier is not particularly limited and may be a general specific surface area of the carrier, but for example, 30 m ² / g or more is preferable, and 100 m ² / g or more is preferable. This is because by increasing the dispersibility and surface area of the catalytic metal supported on the carrier, the catalytic activity can be made sufficient for the production of carbon monoxide.

When the catalyst metal is supported on the carrier, the catalyst precursor solution obtained by dissolving and mixing the catalyst metal precursor in a solvent such as water or ethanol is used, and the catalyst metal is supported on the carrier. The precursor of the catalyst metal is not particularly limited, and examples thereof include metal salts such as chlorides, nitrates, sulfates, and carbonates. The method of supporting the catalyst metal on the carrier is not particularly limited, and a general method can be used, and examples thereof include an impregnation method, a coprecipitation method, a polyol method, and an electroless plating method.

The amount of the catalyst metal supported on the carrier is not particularly limited, but the weight ratio of the catalyst metal to the total weight of the carrier and the catalyst metal is usually preferably in the range of 0.05% by weight to 30% by weight, and particularly 1. It is preferably in the range of 0% by weight to 10% by weight. This is because, for example, the catalytic activity is sufficient for the production of carbon monoxide when the weight ratio of the catalytic metal to the total weight of the carrier and the catalytic metal is equal to or higher than the lower limit of these ranges. When the weight ratio of the catalyst metal to the total weight of the carrier and the catalyst metal is not more than the upper limit of these ranges, for example, the particles of the catalyst metal carried on the carrier aggregate with each other and the specific surface area decreases, so that the desired catalytic activity is obtained. This is because it is possible to suppress the inability to obtain.

The structure and composition of the syngas production catalyst can be specified by, for example, methods such as X-ray photoelectron spectroscopy, fluorescent X-ray analysis, X-ray diffraction analysis, and electron microscope observation.

<Manufacturing method of catalyst for producing synthetic gas>
The method for producing the synthetic gas production catalyst according to the embodiment is not particularly limited as long as it is a method capable of producing the synthetic gas production catalyst according to the embodiment, and the synthetic gas production catalyst is platinum (Pt). When a catalyst metal containing silver (Ag) and a carrier containing cerium oxide (CeO ₂ ) are contained and the catalyst metal is supported on the carrier, the method for producing a catalyst for producing synthetic gas is as follows. For example, the following manufacturing method is used.

First, an aqueous solution of platinum chloride and silver nitrate tetrahydrate are weighed so that the ratio of platinum and silver in atomic% is a desired ratio, placed in a eggplant flask, and then 30 ml of pure water is added. Next, a desired amount of CeO ₂ powder is added as a carrier, and the mixture is stirred with an evaporator for 20 minutes. Next, the pressure is reduced to 100 mbar, and the solvent is removed in a hot water bath at 80 ° C. with stirring to obtain a catalyst precursor powder for synthetic gas production. Next, the catalyst precursor powder for producing synthetic gas is uniformly crushed in a mortar, placed in a quartz boat, and then held in a box furnace at 500 ° C. for 2 hours in an air atmosphere. As a result, a catalyst for producing synthetic gas is obtained. At this time, the rate of temperature rise is 10 ° C./min, and the cooling is natural cooling. As described above, it is possible to produce a catalyst for producing synthetic gas, which comprises a catalyst metal containing platinum and silver and a carrier containing cerium oxide, and the catalyst metal is supported on the carrier.

<Catalyst characteristic evaluation method for catalysts for producing synthetic gas>
For the catalyst characteristics of the catalyst for producing synthetic gas according to the embodiment, a catalyst activity point evaluation device (catalyst analyzer manufactured by Microtrac Bell Co., Ltd.) and a mass analyzer (Thermo Star (registered trademark) manufactured by PFEIFFER VACUUM) are used. Can be evaluated by.

Hereinafter, a specific description will be given. First, about 0.015 g of glass wool is rolled and placed in a glass reaction tube, then a catalyst for producing synthetic gas is weighed by about 0.6 cc and placed in the glass reaction tube, and the glass reaction tube is installed in a catalytic activity evaluation device. ..

Next, while flowing He gas through the glass reaction tube at a flow rate of 100 ccm, the temperature is raised to 400 ° C. at 10 ° C./min and maintained at 400 ° C. for 10 min. Next, the catalyst for producing synthetic gas is reduced by changing the He gas to Ar + ₃ % H2 gas and holding it for 60 minutes while circulating it at a flow rate of 60 ccm.

Next, the Ar + ₃ % H2 gas is changed to He gas, and the temperature is lowered to 200 ° C. at 10 ° C./min while circulating at a flow rate of 100 ccm. Next, by changing the He gas to a mixed gas of Ar + 3% H ₂ gas with a flow rate of 60 ccm and Ar + 3% CO ₂ gas with a flow rate of 20 c cm, and changing the gas flow path from a glass reaction tube to a bypass that does not pass through the glass reaction tube. , Pass the mixed gas through the bypass. Then, after the mixed gas is circulated via the bypass in this way, the ion current value of each m / z in the mixed gas at the outlet of the bypass is measured by a mass analyzer so that it is not affected by the catalytic reaction. The ionic current value of each m / z in the mixed gas is obtained. The mass spectrometer is kept at 150 ° C. in advance.

Next, after obtaining the ion current value of each m / z in the mixed gas that is not affected by the catalytic reaction as described above, the gas flow path is returned from the bypass to the glass reaction tube in which the catalyst is arranged, and the glass reaction is performed. The ionic current value of each m / z in the mixed gas at the outlet of the tube is measured by a mass analyzer. Thereby, the catalytic property of the catalyst for producing a synthetic gas at 200 ° C. is evaluated. Further, after the ion current value of each m / z stabilizes, the temperature is gradually raised to 250 ° C., 300 ° C., 350 ° C., and 400 ° C. at 5 ° C./min, and the catalyst at each temperature of the syngas production catalyst is used. Evaluate the characteristics. This makes it possible to measure the amount of substance of carbon monoxide and the amount of substance of methane produced at each temperature by the catalyst for producing synthetic gas, and the amount of methane produced (material amount) relative to the amount of carbon monoxide produced (material amount). Ratio (CH ₄ / CO), conversion rate of CO ₂ and the like can be obtained.

<Syngas production equipment>
The syngas production apparatus using the reverse shift reaction of the present invention has an introduction path for supplying carbon dioxide and hydrogen, a reaction vessel for performing a reverse shift reaction between carbon dioxide and hydrogen, and heating for adjusting the temperature of the reaction vessel. The reaction vessel is provided with the above-mentioned catalyst for producing synthetic gas of the present invention.

The heating means can be appropriately selected from electric heating, combustion heat and the like. The introduction path may be connected to a carbon dioxide supply facility or a hydrogen supply facility, and a control device for adjusting the gas composition to a desired ratio may be provided.

When carbon monoxide is produced by the reverse shift reaction, methane gas is produced as a by-product. By applying the catalyst for producing synthetic gas of the present invention, it is possible to suppress the production of methane. In particular, the catalyst for producing synthetic gas of the present invention improves the yield of CO at a low temperature of 400 ° C. or lower. Therefore, the temperature of the reaction vessel of the synthetic gas production apparatus can be set at 400 ° C. or lower, and the temperature is lower than before, so that the amount of energy required is small. Further, as the heating means, a means for supplying the waste heat of other equipment to the reaction vessel can be applied. The reaction vessel can be heated by using the exhaust heat of 700 ° C. or lower supplied from other equipment, and as a result, the energy cost required for the syngas production apparatus can be further reduced.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the technical scope of the present invention is not limited to these Examples.

[Example 1]
First, an aqueous solution of platinum chloride and silver nitrate tetrahydrate are weighed so that the ratio of platinum (Pt) and silver (Ag) in atomic% is Pt: Ag = 50: 50, and then placed in a eggplant flask. 30 ml of pure water was added. Next, 3.6 g of CeO ₂ powder was added as a carrier, and the mixture was stirred with an evaporator for 20 minutes. Next, the pressure was reduced to 100 mbar, and the solvent was removed in a hot water bath at 80 ° C. with stirring to obtain a catalyst precursor powder for synthetic gas production. Next, the catalyst precursor powder for producing synthetic gas was uniformly pulverized in a mortar, placed in a quartz boat, and then held in a box furnace at 500 ° C. for 2 hours in an air atmosphere. As a result, a catalyst for producing a synthetic gas having a weight ratio of the catalyst metal to the total weight of the carrier and the catalyst metal of 10% by weight was about 4.0 g was obtained.

[Example 2]
The same as in Example 1 except that the platinum chloride aqueous solution and the silver nitrate tetrahydrate were weighed so that the ratio of Pt and Ag in atomic% was Pt: Ag = 70:30 and stirred together with the carrier. A catalyst for producing synthetic gas was obtained.

[Example 3]
The same as in Example 1 except that the platinum chloride aqueous solution and the silver nitrate tetrahydrate were weighed so that the ratio of Pt and Ag in atomic% was Pt: Ag = 90:10 and stirred together with the carrier. A catalyst for producing synthetic gas was obtained.

[Example 4]
The same as in Example 1 except that the platinum chloride aqueous solution and the silver nitrate tetrahydrate were weighed so that the ratio of Pt and Ag in atomic% was Pt: Ag = 99: 1 and stirred together with the carrier. A catalyst for producing synthetic gas was obtained.

[Example 5]
First, the chloroplatinic acid aqueous solution and the gold chloride aqueous solution were weighed so that the ratio of Pt and gold (Au) in atomic% was Pt: Au = 50: 50, placed in a eggplant flask, and then in Example 1. Similarly, for synthetic gas production as in Example 1, except that pure water was added, the mixture was stirred with the carrier, and the solvent was removed in the same manner as in Example 1 to obtain a catalyst precursor powder for synthetic gas production. Obtained a catalyst.

[Example 6]
Platinum chloride acid aqueous solution and gold chloride aqueous solution were weighed so that the ratio of Pt and Au in atomic% was Pt: Au = 70: 30, and synthesized in the same manner as in Example 5 except that the mixture was stirred with the carrier. A catalyst for gas production was obtained.

[Example 7]
Platinum chloride acid aqueous solution and gold chloride aqueous solution were weighed so that the ratio of Pt and Au in atomic% was Pt: Au = 90:10, and synthesized in the same manner as in Example 5 except that the mixture was stirred with the carrier. A catalyst for gas production was obtained.

[Example 8]
Platinum chloride acid aqueous solution and chloroauric acid aqueous solution were weighed so that the ratio of Pt and Au in atomic% was Pt: Au = 99: 1, and synthesized in the same manner as in Example 5 except that the mixture was stirred with the carrier. A catalyst for gas production was obtained.

[Comparative Example 1]
The same as in Example 1 except that the platinum chloride aqueous solution and the silver nitrate tetrahydrate were weighed so that the ratio of Pt and Ag in atomic% was Pt: Ag = 100: 0 and stirred together with the carrier. A catalyst for producing synthetic gas was obtained.

[Comparative Example 2]
The same as in Example 1 except that the platinum chloride aqueous solution and the silver nitrate tetrahydrate were weighed so that the ratio of Pt and Ag in atomic% was Pt: Ag = 0: 100 and stirred together with the carrier. A catalyst for producing synthetic gas was obtained.

[evaluation]
The crystal structure of the catalyst for producing synthetic gas obtained in Example 1 was identified by X-ray Diffraction measurement. The X-ray diffraction measurement was performed under the following conditions.

Measurement range: 2θ = 10 ° to 80 °
Measurement width: 0.02 °
Tube voltage: 48kV
Tube current: 25mA

FIG. 1 is an X-ray diffraction pattern of the crystal structure of the catalyst for producing synthetic gas obtained in Example 1. In the X-ray diffraction pattern shown in FIG. 1, 2θ = 28.5 °, 33.1 °, 47.8 °, 56.5 °, 59.1 °, 69.4 °, 76.7 °, and 79. A peak derived from CeO ₂ is shown near 0 °, and a very broad peak derived from the (111) plane of platinum (Pt) is shown near 2θ = 41.0 °. Further, in the X-ray diffraction pattern shown in FIG. 1, the peak of silver (Ag) is not shown, and the peak derived from the (111) plane of platinum is shifted to the high angle side. It is suggested that silver may be dissolved in platinum in the catalyst metal of the syngas production catalyst obtained in 1.

The catalytic properties of the synthetic gas production catalysts obtained in Examples 1 to 8 and Comparative Examples 1 and 2 at 350 ° C. were evaluated by the above-mentioned catalyst characteristic evaluation method for the synthetic gas production catalyst. Thereby, the substance amount of carbon monoxide (CO) and the substance amount of methane (CH ₄ ) produced at 350 ° C. by the synthetic gas production catalyst of each example were measured, and 350 of the synthetic gas production catalyst of each example. The ratio (CH ₄ / CO) of the amount of methane produced (material amount) to the amount of carbon monoxide produced (material amount) at ° C was determined. In addition, the conversion rate of CO ₂ at 350 ° C. of the catalyst for producing synthetic gas in each example was determined. FIG. 2 shows the content of silver or gold with respect to the total content of platinum (Pt) and silver (Ag) or gold (Au) in the synthetic gas production catalysts obtained in Examples and Comparative Examples at 350 ° C. It is a graph which shows the relationship with the ratio (CH ₄ / CO) of the production amount (material amount) of methane to the production amount (material amount) of carbon oxide. Further, FIG. 3 shows the relationship between the silver or gold content and the CO ₂ conversion rate at 350 ° C. with respect to the total content of platinum and silver or gold in the synthetic gas production catalysts obtained in Examples and Comparative Examples. It is a graph which shows. In FIG. 3, the conversion rate of CO ₂ of the copper (Cu) catalyst currently used, which is 30%, is also shown by the dotted line.

As shown in FIGS. 2 and 3, in the catalyst obtained in Comparative Example 1, the conversion rate of CO ₂ is as high as 38%, but CH ₄ / CO is as high as 1.2, which is higher than that of CO. Also, a large amount of CH ₄ which is a by-product is produced. On the other hand, in the catalyst obtained in Comparative Example 2, CH ₄ / CO is as low as 0.02, and although CH ₄ is hardly produced, the conversion rate of CO ₂ is as low as 9%.

On the other hand, in the catalysts obtained in Examples 1 to 3 and 5 to 7, CH ₄ / CO was 0.01, 0.02, 0.09, 0.01, 0.02, and 0.09, respectively. The production of CH ₄ is almost suppressed. Further, even in the catalysts obtained in Examples 4 and 8, CH ₄ / CO is 0.2 in both cases, and more CO is produced than CH ₄ . Further, in the catalysts obtained in Examples 1 to 8, the conversion rates of CO ₂ are 30%, 28%, 37%, 38%, 30%, 30%, 37%, and 38%, respectively. It shows a high value equal to or higher than that of the Cu catalyst currently used. From these results, it can be seen that the catalyst obtained in the example was able to reduce the amount of CH ₄ produced while exhibiting a high CO ₂ conversion rate by adding Ag or Au to Pt. This is because the 5d electron orbit of Pt is filled with Ag or Au to suppress the dissociation adsorption of CO ₂ or CO adsorbed on the Pt surface, the reaction between Pt and Ag or Au, and Pt and Ag. Alternatively, it is considered that the reaction between Au and CeO ₂ between the three phases is the cause.

The Cu catalyst currently used has a conversion rate of CO ₂ of 30% and CH ₄ / CO of 0, that is, a selectivity of CO of 100%, so that the yield of CO is 30%. On the other hand, the relationship between the content of Ag or Au and CH ₄ / CO at 350 ° C. with respect to the total content of Pt and Ag or Au shown in FIG. 2, and the relationship between Pt and Ag or Au shown in FIG. From the relationship between the content of Ag or Au with respect to the total content of Pt and the conversion rate of CO ₂ at 350 ° C., the content of Ag or Au with respect to the total content of Pt and Ag or Au is 1 atomic% or more and 25 atoms. When it is within the range of% or less, the conversion rate of CO ₂ is 30% or more, which is the conversion rate of CO ₂ of the Cu catalyst, and the yield of CO is 30% or more, which is the yield of CO ₂ of the Cu catalyst. It is thought that it can be. That is, it is considered that the production of CH ₄ can be suppressed particularly effectively, and the yield of CO can be particularly effectively improved by suppressing the decrease in the conversion rate of CO ₂ .

The present invention is not limited to the above-described embodiment and the above-mentioned embodiment, but has substantially the same configuration as the technical idea described in the claims of the present invention, and exhibits the same function and effect. Anything is included in the technical scope of the invention and includes various modifications. For example, the above-described embodiment and the above-mentioned embodiment have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment and embodiment with the configuration of another embodiment and embodiment, and the configuration of one embodiment and example can be replaced with the configuration of another embodiment and embodiment. It is also possible to add configurations. Further, it is possible to add / delete / replace other configurations with respect to a part of the configurations of each embodiment and each embodiment.

Claims (8)

A catalyst for producing synthetic gas used for producing carbon monoxide by reacting carbon dioxide with hydrogen, at least one selected from the group consisting of platinum and silver, copper, zinc, and gold. A catalyst for producing synthetic gas, which comprises a catalyst metal containing and. The catalyst for producing a synthetic gas according to claim 1, further comprising a carrier, wherein the catalyst metal is supported on the carrier. The catalyst for producing a synthetic gas according to claim 2, wherein the carrier contains cerium oxide. The catalyst for producing synthetic gas according to any one of claims 1 to 3, wherein the catalyst metal contains the platinum and the silver or gold. The fourth aspect of claim 4, wherein the content of the silver or gold with respect to the total content of the platinum and the silver or gold in the catalyst metal is in the range of 1 atomic% or more and 25 atomic% or less. Catalyst for synthetic gas production. A synthetic gas production apparatus having an introduction path for supplying carbon dioxide and hydrogen, a reaction vessel for reacting carbon dioxide and hydrogen, and a heating means for adjusting the temperature of the reaction vessel.
A synthetic gas production apparatus comprising the catalyst for producing synthetic gas according to any one of claims 1 to 5 in the reaction vessel. The synthetic gas production apparatus according to claim 6, wherein the waste heat of another device is used for heating the reaction vessel. The synthetic gas production apparatus according to claim 6 or 7, wherein the temperature of the synthetic reaction in the reaction vessel is set to 400 ° C. or lower.

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