JP2021115508A - Modification catalyst and manufacturing method thereof - Google Patents

Abstract

To provide a modification catalyst of which catalyst performance is difficult to be deteriorated by a sulfur component contained in fuel gas and a manufacturing method thereof.SOLUTION: The modification catalyst 1 comprises a composite powder 10 represented by (BaO1-a(CO3)a)YM14-cM2cO6-b (here, 0≤a≤1, 0≤b≤4.5, 0≤c<4). A manufacturing of the modification catalyst 1 includes a step for preparing at least basis particle powder represented by BaYM14-cM2cO7+σ(here, 0≤c<4, 0<σ≤1.5), and a step of generating composite powder represented by base particle powder represented by (BaO1-a(CO3)a)YM14-cM2cO6-b (here, 0≤a≤1,0≤b≤4.5, 0≤c<4) by heating at least the basis particle powder in reducing gas containing CO2 or in the reducing gas containing no CO2. However, M1 and M2 are transition metals selected from the group consisting of CO, V, Cr, Mn, Fe, Ni, Cu and Zn, respectively.SELECTED DRAWING: Figure 1

Description

The present invention relates to a reforming catalyst and a method for producing the same.

Conventionally, a reforming catalyst has been used for steam reforming a fuel gas such as a hydrocarbon or an oxygen-containing hydrocarbon. For example, in the vehicle field such as automobiles, since the fuel gas is steam reformed by using the steam contained in the exhaust gas, the exhaust gas recirculation route in the exhaust recirculation device that re-intakes a part of the exhaust gas discharged from the internal combustion engine. A reforming catalyst may be placed in.

The catalyst performance of the conventional reforming catalyst tends to deteriorate due to the sulfur component contained in the fuel gas. Therefore, a sulfur component adsorbent that selectively adsorbs the sulfur component is arranged on the upstream side of the reforming catalyst, and the reforming catalyst arranged on the downstream side is protected from the sulfur component. Further, a technique for regenerating a reforming catalyst by heating a sulfur-poisoned reforming catalyst to release a sulfur component is also known.

In the preceding Patent Document 1, the general formula: L _1-x Ba _x CoO _y (however, the L component is a lanthanoid (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho). , Er, Tm, Yb, Lu), which is at least one of the elements and contains a material of 0 <x ≦ 1, 2 ≦ y ≦ 4).

Special Table 2009-501078

The above-mentioned technique using a sulfur component adsorbent cannot protect the reforming catalyst when a sulfur component exceeding an adsorbable amount comes. Further, in this technique, a large amount of sulfur component adsorbent is required in order to sufficiently suppress the deterioration of the catalytic performance of the reforming catalyst. On the other hand, the technique of regenerating the reforming catalyst cannot be reformed at the time of the regeneration process, so that the fuel consumption is deteriorated. From the above, there is a demand for a reformed catalyst in which the catalyst performance is not easily deteriorated by the sulfur component contained in the fuel gas.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a reformed catalyst in which the catalyst performance is not easily deteriorated by the sulfur component contained in the fuel gas, and a method for producing the same.

One aspect of the present invention is the general formula: (BaO _1-a (CO ₃ ) _a ) YM1 _4-c M2 _c O _6-b (where 0 ≦ a ≦ 1, 0 ≦ b ≦ 4.5, 0 ≦ It is in the reforming catalyst (1) containing the composite powder (10) represented by c <4).
However, the above M1 and the above M2 are transition metals selected from the group consisting of Co, V, Cr, Mn, Fe, Ni, Cu, and Zn, respectively, so as to be different from each other.

Another aspect of the present invention is _{a preparatory step of preparing at least the base particle powder represented by the general formula: BaYM1 4-c} M2 _c O _{7 + σ} (where 0 ≦ c <4, 0 <σ ≦ 1.5). ,
By heat-treating at least the base particles powder in a reducing gas containing no in a reducing gas or CO ₂ containing CO _2, the general _{formula: (BaO 1-a (CO} 3) a) YM1 4-c M2 _{A production step for producing a composite powder represented by c} O _6-b (however, 0 ≦ a ≦ 1, 0 ≦ b ≦ 4.5, 0 ≦ c <4).
It is in the method of manufacturing a reforming catalyst having.
However, the above M1 and the above M2 are transition metals selected from the group consisting of Co, V, Cr, Mn, Fe, Ni, Cu, and Zn, respectively, so as to be different from each other.

The reforming catalyst contains the composite powder. Therefore, the catalyst performance of the reforming catalyst is unlikely to deteriorate due to the sulfur component contained in the fuel gas.

The method for producing a reforming catalyst has each of the above steps. Therefore, according to the method for producing the reformed catalyst, it is possible to suitably produce the reformed catalyst in which the catalyst performance is not easily deteriorated by the sulfur component contained in the fuel gas.

The reference numerals in parentheses described in the scope of claims and the means for solving the problem indicate the correspondence with the specific means described in the embodiments described later, and limit the technical scope of the present invention. It's not a thing.

FIG. 1 is a diagram schematically showing an example of the reforming catalyst according to the first embodiment. FIG. 2 is a diagram schematically showing an example of the microstructure of the reforming catalyst according to the first embodiment. FIG. 3 is a diagram schematically showing an example of a HAADF-STEM image of a reforming catalyst by a high-resolution scanning transmission electron microscope (HR-STEM).

The reforming catalyst of the present embodiment has a general formula: (BaO _1-a (CO ₃ ) _a ) YM1 _4-c M2 _c O _6-b (where 0 ≦ a ≦ 1, 0 ≦ b ≦ 4.5, It contains a composite powder (10) represented by 0 ≦ c <4). However, the above M1 and the above M2 are transition metals selected from the group consisting of Co, V, Cr, Mn, Fe, Ni, Cu, and Zn, respectively, so as to be different from each other. Therefore, the reforming catalyst of the present embodiment is unlikely to deteriorate in catalytic performance due to the sulfur component contained in the fuel gas.

This composite powder in the reforming catalyst of the present embodiment, toxic sulfur component contained in the fuel gas _{^{(S, S 2-, SO,}} SO 2, SO 3, SO 4 2- , etc.) occludes It can also react the toxic sulfur component with hydrogen and carbon monoxide generated by steam reforming of the fuel gas to make a sulfur compound gas with a low effect on catalyst deterioration (detoxify the toxic sulfur component). It is thought that this is due to being able to do). Therefore, according to the reformed catalyst of the present embodiment, the catalytic function can be exhibited for a long time without using a sulfur component adsorbent. Further, according to the reformed catalyst of the present embodiment, it is not necessary to control the regeneration process and the like, and it is easy to improve the fuel efficiency. Hereinafter, the reforming catalyst of the present embodiment will be described in detail with reference to the drawings.

(Embodiment 1)
The reforming catalyst of the first embodiment will be described with reference to FIG. As illustrated in FIG. 1, the reforming catalyst 1 of the present embodiment contains the composite powder 10. The composite powder 10 has a general formula: (BaO _1-a (CO ₃ ) _a ) YM1 _4-c M2 _c O _6-b (where 0 ≦ a ≦ 1, 0 ≦ b ≦ 4.5, 0 ≦ c. It is represented by <4). However, M1 and M2 are different from each other in that they are Co (cobalt), V (vanadium), Cr (chromium), Mn (manganese), Fe (iron), Ni (nickel), Cu (copper), and , Zn (zinc) is a transition metal selected from the group.

In the general formula of the composite powder 10, a is a sulfur compound gas SG having an excessive adsorption force of the toxic sulfur component Sc, which makes it easy to suppress a change in the fuel reforming rate with time, and has a low influence on catalyst deterioration. From the viewpoint of improving the activity of the alteration reaction, it is preferably more than 0, more preferably 0.1 or more, still more preferably 0.2 or more, even more preferably 0.3 or more, and even more. Preferably, it can be 0.4 or more. Further, a is preferably less than 1 from the viewpoint of suppressing a decrease in the reaction frequency for converting the toxic sulfur component Sc into a sulfur compound gas SG having a low degree of influence on catalyst deterioration due to insufficient adsorption power. , More preferably 0.9 or less, still more preferably 0.8 or less, even more preferably 0.7 or less, and even more preferably 0.6 or less.

In the general formula of the composite powder 10, b is the activity of the reaction of transforming the toxic sulfur component Sc into a sulfur compound gas SG having a low influence on catalyst deterioration, which makes it easy to suppress the change of the fuel reforming rate with time. It is preferably more than 0, more preferably 0.5 or more, still more preferably 1 or more, even more preferably 1.5 or more, and even more preferably 2 or more, from the viewpoint of improving be able to. Further, b is preferably less than 4.5, more preferably less than 4.5, from the viewpoint of improving the activity of the reaction of transforming the toxic sulfur component Sc into a sulfur compound gas SG having a low influence on catalyst deterioration. It can be 4 or less, more preferably 3.5 or less, and even more preferably 3 or less.

In the general formula of the composite powder 10, M2 is a substitution element of M1. When c = 0, M1 is not replaced by M2. When 0 <c <4, a part of M1 is replaced with M2. In this case, c is preferably 0.3 or more, more preferably 0.6 or more, still more preferably 0.8 or more, from the viewpoint of enhancing the shape retention ability in the fuel reforming environment. Can be done. Further, in this case, c is preferably 2 or less, more preferably 1.5 or less, still more preferably 1.2 or less, from the viewpoint of enhancing the shape retention ability in the fuel reforming environment. Can be done.

In the general formula of the composite powder 10, M1 can preferably be Co. That is, the composite powder 10 has a general formula: (BaO _1-a (CO ₃ ) _a ) YCo _4-c M2 _c O _6-b (however, 0 ≦ a ≦ 1, 0 ≦ b ≦ 4.5, 0). The configuration can be represented by ≦ c <4). However, M2 is a transition metal selected from the group consisting of V, Cr, Mn, Fe, Ni, Cu, and Zn. According to this configuration, it is possible to ensure that the deterioration of the catalyst performance due to the sulfur component Sc contained in the fuel gas FG is suppressed.

In the general formula of the composite powder 10, M1 can be Co and c = 0 more preferably. In other words, the composite powder 10 has the general _{formula: (BaO 1-a (CO} 3) a) YCo 4 O 6-b ( where, 0 ≦ a ≦ 1,0 ≦ b ≦ 4.5) is represented by the structure Can be. According to this configuration, it is possible to more reliably suppress the deterioration of the catalyst performance due to the sulfur component Sc contained in the fuel gas FG.

As illustrated in FIG. 2, the composite powder 10 includes at least one of the base particles 101, the BaCO ₃ fine particles 102 attached to the surface of the base particles 101, and the M1 fine particles and the M2 fine particles attached to the surface of the base particles 101. It can be configured to include a transition metal fine particle 103 composed of one. According to this configuration, it is possible to ensure that the deterioration of the catalyst performance due to the sulfur component Sc contained in the fuel gas FG is suppressed. _{This is because the BaCO 3} fine particles 102 and the transition metal fine particles 103 are highly dispersed and arranged on the surface of the base particles 101, so that the adsorption of the sulfur component Sc, which is considered to be _{mainly contributed by the BaCO 3 fine particles 102, and the main} The formation of sulfur compound gas SG, which has a low influence on catalyst deterioration due to the reaction with _{H 2} and CO gas (generated in the atmosphere by steam reforming) in the reformed gas RG, which is considered to be contributed by the transition metal fine particles 103. However, it is presumed that this is because it occurs with high efficiency in a desired temperature range (for example, 300 ° C. or higher and 900 ° C. or lower).

Specifically, the base particle 101 _{may have a configuration represented by the general formula: BaYM1 4-c} M2 _c O _{7 + σ} (where 0 ≦ c <4, 0 <σ ≦ 1.5). M1 and M2 are transition metals selected from the group consisting of Co, V, Cr, Mn, Fe, Ni, Cu, and Zn, respectively, so as to be different from each other. The Y (yttrium) in the base particles 101 is difficult to be reduced by the reducing gas (details will be described later) when the composite powder 10 is generated, maintains the oxide state, and is the BaCO ₃ fine particles 102 and the transition metal. It is suitable for holding the fine particles 103.

In the general formula of the base particle 101, M2 is a substitution element of M1. When c = 0, M1 is not replaced by M2. When c is 0 <c <4, a part of M1 is replaced with M2. In this case, c is preferably 0.3 or more, more preferably 0.6 or more, still more preferably 0.8 or more, from the viewpoint of enhancing the shape retention ability in the fuel reforming environment. Can be done. Further, in this case, c is preferably 2 or less, more preferably 1.5 or less, still more preferably 1.2 or less, from the viewpoint of enhancing the shape retention ability in the fuel reforming environment. Can be done.

In the general formula of the base particle 101, σ can be preferably more than 0, more preferably 0.1 or more, from the viewpoint of improving the fuel reforming rate. Further, σ is preferably less than 1.5, more preferably 1 or less, still more preferably 0.5 or less, still more preferably 0.2 or less, from the viewpoint of improving the fuel reforming rate. Can be.

In the general formula of the base particle 101, M1 can preferably be Co. That is, the base particle 101 _{can be configured to be represented by the general formula: BaYCo 4-c} M2 _c O _{7 + σ} (where 0 ≦ c <4, 0 <σ ≦ 1.5). However, M2 is a transition metal selected from the group consisting of V, Cr, Mn, Fe, Ni, Cu, and Zn. According to this configuration, it is possible to ensure that the deterioration of the catalyst performance due to the sulfur component Sc contained in the fuel gas FG is suppressed.

In the general formula of the base particle 101, more preferably, M1 can be Co and c = 0. That is, the base particle 101 _{can have a configuration represented by the general formula: BaYCo 4} O _{7 + σ} (where 0 <σ ≦ 1.5). According to this configuration, it is possible to more reliably suppress the deterioration of the catalyst performance due to the sulfur component Sc contained in the fuel gas FG. This is because the transition metal fine particles 103 composed of Co fine particles are present around the _{BaCO 3} fine particles 102 on the surface of the base particles 101, _{so that the sulfur component Sc adsorbed on the BaCO 3} fine particles 102 and the steam of the fuel gas FG It is considered that this is because the production of the sulfur compound gas SG having a low influence on the catalyst deterioration due to the reaction with _{the H 2} and CO gas in the atmosphere generated by the reforming is promoted.

Both the composite powder 10 and the base particle 101 are oxides. The amount of oxygen in the general formula of each oxide can be identified by the Infrared gas melting-infrared absorption method. Specifically, in a helium gas atmosphere as an inert gas, when a graphite crucible is pressed between the upper and lower electrodes of the extraction furnace and a large current is passed, the crucible itself rapidly becomes hot due to Joule heat. The oxide sample is put into a graphite crucible that has been degassed once in a high temperature state, and the oxide sample is thermally decomposed in a high temperature state again. Oxygen contained in the oxide sample reacts with carbon in the graphite abutment to become carbon monoxide (CO) gas, and the generated CO gas is transported to the carrier gas and detected by a non-dispersed infrared detector. The amount of oxygen in the oxide sample can be identified from the amount of CO detected.

The atomic number ratio of each metal element in the general formula of the composite powder 10 and the base particle 101 can be measured by high frequency inductively coupled plasma atomic emission spectrometry (ICP-AES).

When the composite powder 10 contains the base particles 101, the BaCO ₃ fine particles 102, and the transition metal fine particles 103, _{the average particle size of the BaCO 3} fine particles 102 is 10 nm or more and 50 nm or less, and the average particle size of the transition metal fine particles 103 is 0.5 nm or more. It can be 30 nm or less. According to this configuration, it is possible to more reliably suppress the deterioration of the catalytic performance with time due to the sulfur component Sc contained in the fuel gas FG. The average particle size of the BaCO ₃ fine particles 102 can be preferably 10 nm or more, more preferably 15 nm or more, still more preferably 20 nm or more, from the viewpoint of enhancing the shape retention ability in a fuel reforming environment. .. The average particle size of the BaCO ₃ fine particles 102 can be preferably 45 nm or less, more preferably 40 nm or less, and further preferably 30 nm or less from the viewpoint of improving the fuel reforming rate. The average particle size of the transition metal fine particles 103 is preferably 1 nm or more, more preferably 2 nm or more, still more preferably 4 nm or more, from the viewpoint of enhancing the shape retention ability in a fuel reforming environment. Can be done. The transition metal fine particles 103 can be preferably 25 nm or less, more preferably 20 nm or less, still more preferably 10 nm or less from the viewpoint of improving the fuel reforming rate.

The average particle size can be measured using a high-resolution scanning transmission electron microscope (HR-STEM) and an energy dispersive X-ray spectrometer (EDS). Specifically, an observation image (HAADF-STEM image) of the reforming catalyst 1 as shown in FIG. 3 is acquired using a high-resolution scanning transmission electron microscope. Next, EDS analysis is performed on each particle on the surface of the base particle 101 in the obtained observation image. Then, the particles in which the Ba element and the C element are detected are _{determined to be BaCO 3} fine particles 102. Further, the particles in which the transition metal element is detected are determined to be the transition metal fine particles 103. Next, each particle size is calculated from the scale in the observation image. Next, the arithmetic mean value of the particle sizes _{of the 30 BaCO 3} fine particles 102 in the observation image is taken as the average particle size of the _{BaCO 3 fine particles 102.} Further, the arithmetic mean value of the particle diameters of the 30 transition metal fine particles 103 in the observation image is taken as the average particle diameter of the transition metal fine particles 103.

When the composite powder 10 contains the base particles 101, the BaCO ₃ fine particles 102, and the transition metal fine particles 103, the _{amount of the BaCO 3} fine particles 102 adhered to the surface of the base particles 101 is such that the sample of the composite powder 10 is placed in an inert gas atmosphere. It can be identified from the amount of carbon dioxide released at 400 ° C. or higher and 1500 ° C. or lower, which is the barium carbonate decomposition temperature range.

The reforming catalyst 1 can contain the catalyst metal 11 in addition to the composite powder 10. In this case, the composite powder 10 can function as a carrier that supports the catalyst metal 11. Further, as illustrated in FIG. 1, the reforming catalyst 1 can include a catalyst metal 11 and a carrier 12 that supports the catalyst metal 11. According to this configuration, steam reforming of the fuel gas FG and detoxification of the sulfur component Sc (conversion to the sulfur compound gas SG having a low influence on catalyst deterioration) can be ensured. Further, according to this configuration, the degree of freedom in selecting the carrier is higher than in the case where the composite powder 10 is used as the carrier of the catalyst metal 11, so that the electronic state of the catalyst metal 11 can be easily made more suitable for steam reforming. There is also an advantage. The support described above includes not only the case where the catalyst metal 11 is supported on the surface of the carrier 12, but also the case where the catalyst metal 11 is contained inside the carrier 12. Note that FIG. 1 shows an example in which the catalyst metal 11 is supported on the surface of the carrier 12. Further, the reforming catalyst 1 can include a void 13 through which the fuel gas FG and the reforming gas RG flow.

Specific examples of the catalyst metal 11 include Rh (rhodium), Pt (platinum), Pd (palladium), Ru (ruthenium), Ir (iridium), Au (gold), Ag (silver), and Os (osmium). , Ni, Co, Fe, and at least one metal selected from the group consisting of Cu, or an alloy of these metals can be preferably used. According to this configuration, it is possible to ensure the reforming activity of the reforming catalyst 1. The catalyst metal 11 is preferably at least one metal selected from the group consisting of Rh, Pt, Pd, Ru, Ir, Au, Ag, and Os, or an alloy of these metals, more preferably. , Rh.

Specific examples of the carrier 12 include ceria zirconia composite oxide, titania (TiO ₂ ), and alumina (Al ₂ O ₃ ). These can be used alone or in combination of two or more. Specifically, the ceria zirconia composite oxide has a general formula: Ce _1-x Zr _x O ₂ (where 0.05 ≦ X ≦ 0.5, preferably 0.1 ≦ X ≦ 0.4, and further. Preferably, those represented by 0.2 ≦ X ≦ 0.3) can be preferably used.

When the reforming catalyst 1 is composed of a mixture containing the composite powder 10, the catalyst metal 11, and the carrier 12, the mass ratio of the composite powder 10 to the carrier 12 can be 20% or more and 80% or less. .. According to this configuration, the catalytic function can be exerted for a long time, so that it becomes easy to suppress the time-dependent change of the fuel reforming rate. The mass ratio of the composite powder 10 to the carrier 12 can be preferably 25% or more, more preferably 30% or more. The mass ratio of the composite powder 10 to the carrier 12 can be preferably 75% or less, more preferably 70% or less. The mass ratio of the composite powder 10 is the mass percentage of the mass of the composite powder 10 to the total mass of the composite powder 10 and the carrier 12 (= 100 × (mass of the composite powder 10) / (composite powder 10 and). The total mass of the carriers 12)).

Examples of the fuel gas FG steam reformed by the reforming catalyst 1 include at least one of hydrocarbons and oxygen-containing hydrocarbons. Hydrocarbons may basically contain carbon atoms and hydrogen atoms, for example, _{alkanes represented by C n} H _{2n + 2} (n: natural number) such as methane, ethane, propane, butane, and them. The structural isomers of the above can be exemplified. Further, the hydrocarbon may contain a cyclic, double bond, benzene ring or the like. The oxygen-containing hydrocarbon is a hydrocarbon containing an oxygen atom, and examples thereof include alcohols such as methanol and ethanol, ethers, epoxides, and carboxylic acids. These can be used alone or in combination of two or more. Further, hydrocarbons and oxygen-containing hydrocarbons also include gasoline, light oil, ethanol-blended gasoline and the like.

The form of the reforming catalyst 1 is not particularly limited, and can be appropriately selected depending on the intended use. Examples of the form of the reforming catalyst 1 include a honeycomb shape, a pellet shape, a plate shape, a powder shape, and a film shape. Further, the reforming catalyst 1 can also be coated (fixed) on a base material such as a honeycomb base material, a pellet base material, and a plate base material. In this case, examples of the material of the base material include ceramics such as cordierite, silicon carbide, and mullite, and metal materials such as stainless steel containing chromium and aluminum.

(Embodiment 2)
The method for producing the reforming catalyst of the second embodiment will be described. In addition, among the codes used in the second and subsequent embodiments, the same codes as those used in the above-described embodiments represent the same components and the like as those in the above-mentioned embodiments, unless otherwise specified.

The method for producing a reformed catalyst of the present embodiment (hereinafter, may be referred to as the present production method) includes a preparation step and a production step.

The preparation step is a step of preparing at least the base particle powder represented by the general formula: BaYM1 _4-c M2 _c O _{7 + σ} (where 0 ≦ c <4, 0 <σ ≦ 1.5). However, M1 and M2 are transition metals selected from the group consisting of Co, V, Cr, Mn, Fe, Ni, Cu, and Zn, respectively, so as to be different from each other. Since the general formula of the base particle powder in the present production method is the same as the base particle 101 in the composite powder 10 described above in the first embodiment, the description thereof will be omitted.

For the base particle powder, for example, Ba salt, Y salt, M1 salt, and M2 salt are weighed so that Ba, Y, M1, and M2 have a predetermined molar ratio, and these are dissolved in water to form an aqueous solution. Is produced, the aqueous solution is sprayed and dried to form granulated powder, and the obtained granulated powder is tentatively fired in an air atmosphere. Examples of the salts of the above metals include acetates, nitrates, sulfates, chlorides and the like.

Generation step, by heat-treating at least the base particles powder in a reducing gas containing no reducing gas or CO ₂ containing CO _2, the general _{formula: (BaO 1-a (CO} 3) a) YM1 4 _-c M2 _c O _6-b (where, 0 ≦ a ≦ 1,0 ≦ b ≦ 4.5,0 ≦ c <4) is a step of producing a composite powder represented by.

Specifically, the reducing gas containing CO _{2 can include a CO 2} gas, a reducing gas, and a base gas composed of an inert gas. Specifically, the reducing gas containing no CO ₂ can include a reducing gas and a base gas composed of an inert gas. Examples of the reducing gas include hydrogen gas, carbon monoxide gas, hydrocarbon gas, and ammonia gas. Further, as the inert gas, for example, nitrogen gas, helium gas, argon gas and the like can be exemplified. The _{reducing gas containing CO 2} is used when producing the composite powder 10 in which 0 <a. On the other hand, the _{reducing gas containing no CO 2} is used when producing the composite powder 10 having a = 0.

The concentration of the reducing gas contained in the reducing gas can be, for example, 1% by volume or more and 10% by volume or less. _{The concentration of CO 2} gas contained in the reducing gas can be, for example, 1% by volume or more and 90% by volume or less.

The heat treatment temperature can be, for example, 800 ° C. or higher and 1000 ° C. or lower. The heat treatment time can be, for example, 0.5 hours or more and 10 hours or less. The heat treatment pressure can be, for example, 0.1 atm or more and 5 atm or less.

When producing a modified catalyst containing a composite powder, a catalyst metal, and a carrier, for example, a mixed powder in which a base particle powder and a carrier powder are mixed can be prepared in a preparation step. In this case, at least a step of supporting the catalyst metal on the carrier powder can be added before the above-mentioned production step. At this time, the catalyst metal can be supported on the mixed powder, that is, the catalyst metal can be supported not only on the carrier powder but also on the base particle powder. In addition, for example, after the above-mentioned production step, a step of mixing the composite powder and the carrier powder carrying the catalyst metal can be added.

When producing a modified catalyst containing a composite powder and a catalyst metal and not containing a carrier, a step of supporting the catalyst metal on the base particle powder can be added before the above-mentioned production step. In addition, for example, after the above-mentioned production step, a step of supporting the catalyst metal on the composite powder can be added. In these cases, the composite powder functions as a carrier.

The mixing method in the above is not particularly limited, but for example, a method of dry mixing with a mixer such as a tumbler mixer, a double cone mixer, a V-type mixer, a kneader kneader, a bag mixer mixer, a ball mill, or the like. A method of wet mixing and then drying in the mixer of the above can be exemplified. Water or an organic solvent can be used as the solvent at the time of wet mixing, and a desired amount of binder can be mixed in order to improve the dispersed state and the like.

Further, as a method of supporting the catalyst metal, for example, a method of impregnating a solution of a catalyst metal salt with a carrier or a carrier and a composite powder and then firing, and a method of converting a solution of the catalyst metal salt into a carrier or a carrier and a composite powder. Examples thereof include a method in which the material is adsorbed and supported and then fired. For example, when Pt is used as the catalyst metal, examples of the platinum salt include acetates, carbonates, nitrates, ammonium salts, citrates, dinitrodiammine salts of platinum, and solutions thereof, and among them, they are supported. From the viewpoint of ease and high dispersibility, dinitrodiammine salt is preferable. For example, when Rh is used as the catalyst metal, examples of the rhodium salt include a solution of rhodium acetate, carbonate, nitrate, ammonium salt, citrate, dinitrodiammine salt or a complex thereof, and among them, the rhodium salt is supported. Nitrate is preferred from the standpoint of ease and high dispersibility. As the solvent, for example, a solvent capable of dissolving the catalytic metal salt in an ionic state, such as water (preferably pure water such as ion-exchanged water and distilled water), is preferable.

Firing in such a supporting method can be carried out in the atmosphere. The firing temperature is preferably 200 to 600 ° C. When the calcination temperature is less than the above lower limit, the platinum group metal compound is not sufficiently thermally decomposed, and it becomes difficult for the platinum group metal compound to be in a metallic state exhibiting catalytic activity, so that the activity tends to be low. On the other hand, when the above upper limit is exceeded, the supported platinum group metal tends to grow into grains and the catalytic activity in the steam reforming reaction of the fuel gas tends to decrease. The firing time is preferably 0.1 to 100 hours. When the calcination time is less than the above lower limit, the platinum group metal compound is not sufficiently thermally decomposed, and it becomes difficult for the platinum group metal compound to be in a metallic state exhibiting catalytic activity, so that the activity tends to be low. On the other hand, even if the above upper limit is exceeded, no further effect can be obtained, which leads to an increase in the cost for preparing the catalyst.

In the present production method, the composite powder produced in the production step is composed _{of at least one of the base particles, BaCO 3} fine particles adhering to the surface of the base particles, and M1 fine particles and M2 fine particles adhering to the surface of the base particles. It can be configured to include transition metal fine particles to be formed. That is, in the production step, by heat-treating the base particle powder in a reducing gas atmosphere, BaCO ₃ fine particles and transition metal fine particles can be precipitated on the surface of the base particles.

According to this configuration, it is possible to ensure that the deterioration of the catalyst performance due to the sulfur component contained in the fuel gas is suppressed. Since the general formula of the base particles is the same as that of the base particles 101 in the composite powder 10 described above in the first embodiment, the description thereof will be omitted.

This manufacturing method has each of the above steps. Therefore, according to the present production method, the reformed catalyst of the first embodiment in which the catalyst performance is not easily deteriorated by the sulfur component contained in the fuel gas can be suitably produced.

(Experimental example)
-Preparation of reforming catalyst for Samples 1 to 26-
_{Y (CH 3 COO) 3 ·} 4H2O, Ba and _{(CH 3 COO) 2, Co} (CH 3 COO) 2 · 4H 2 O, Y: Ba: Co = 1: 1: weighed such that the molar ratio of 4 did. Then, these were dissolved in pure water to prepare an aqueous acetate solution. The prepared aqueous acetate solution was spray-dried to obtain a powder. The obtained powder was calcined in air at 600 ° C. for 7 hours to prepare _{BaYCo 4} O _{7.1 powder as a base particle powder used for producing a composite powder.}

In addition, _{each base particle powder was prepared by substituting a part of Co in BaYCo 4} O _7.1 with V, Cr, Mn, Fe, Ni, Cu, and Zn. At this _{time, VCl 3, Mn (CH 3} COO) 2 · 4H 2 O, Fe (NO 3) 3 · 9H 2 O, Ni (CH 3 COO) 2, Cu (CH 3 COO) 2, Zn (CH 3 COO ) ₂ was used and weighed so that Co to V, Cr, Mn, Fe, Ni, Cu, and Zn had a molar ratio of 3: 1 in the same manner as above. As a result, as the base particle powder used for producing the composite powder, BaYCo ₃ V ₁ O _7.1 powder, BaYCo ₃ Cr ₁ O _7.1 powder, BaYCo ₃ Mn ₁ O _7.1 powder, BaYCo ₃ Fe ₁ O _7.1 powder, BaYCo ₃ Ni ₁ O _7.1 powder, BaYCo ₃ Cu ₁ O _7.1 powder, and BaYCo ₃ Zn ₁ O _7.1 powder were prepared, respectively.

In addition, a base particle powder in which all of Co in the _{BaYCo 4} O _{7.1 powder was Fe was prepared.} In this case, Fe _{(NO 3)} using the _{3 · 9H 2 O, Y:} Ba: Fe = 1: 1: except that weighed so a molar ratio of 4, and in the same manner as above. _{As a result, BaYFe 4} O _7.1 powder was produced as a base particle powder used for producing the composite powder.

_{Next, 3 g of BaYCo 4} O _7.1 powder as a base particle powder and 7 g of CeO-ZrO powder (Ce _0.75 Zr _0.25 O ₂ powder) as a carrier powder were added to 25 g of ion-exchanged water. This was mixed with 150 g of zirconia balls having a diameter of 5 mm, and mixed by ball milling for 3 hours in a 250 cc pot. As a result, a mixed powder for producing the reforming catalyst of Sample 1 in which the base particle powder and the carrier powder were mixed was prepared. In the same manner, each mixed powder for preparing the reforming catalyst of Samples 2 to 26, in which the base particle powder and the carrier powder were mixed in the combinations shown in Tables 1 and 2 described later, was prepared. The mixing of the base particle powder and the carrier powder in each mixed powder was carried out so that the mass ratio of the composite powder and the mass ratio of the carrier were the values shown in Tables 1 and 2 described later.

Next, a cordierite honeycomb base material (400 cells / square inch) having a diameter of 23 mm and a length of 25 mm was coated with a mixed powder so as to be 240 g per 1 L of the honeycomb base material. Next, the honeycomb base material coated with the above mixed powder was immersed in 20 cc of a rhodium nitrate aqueous solution containing 50 mg of rhodium for 12 hours, and then dried at 120 ° C. for 10 minutes. Then, this was calcined at 500 ° C. for 3 hours in an air atmosphere to support the catalyst metal on the mixed powder. The amount of rhodium supported as the catalyst metal was 4.8 g / L.

Next, each mixed powder coated on the honeycomb substrate contains a predetermined concentration of CO ₂ gas, a predetermined concentration of H ₂ gas, and a predetermined base gas, as shown in Tables 3 and 4 described later. The heat treatment was performed in a reducing gas atmosphere at a predetermined heat treatment temperature and heat treatment time. As a result, a reforming catalyst for Samples 1 to 26 was obtained. The reforming catalysts of Samples 1 to 13 and Samples 15 to 26 contain a catalyst metal, a carrier, and a composite powder. Further, the reforming catalyst of the sample 14 contains a catalyst metal and a composite powder.

The detailed composition of the composite powder in the reforming catalyst of each sample was measured by the above-mentioned measuring method. The results are summarized in Tables 1 and 2 described later.

An inert gas melting-infrared absorption analyzer "EMGA-620W" manufactured by HORIBA, Ltd. was used as an analyzer for analyzing the amount of oxygen in the general formula of each oxide. As the flux, 0.5 g of tin pellets, which is a decomposition accelerator manufactured by HORIBA, Ltd., was used, and the flux was ultrasonically cleaned in hexane and then air-dried with a dryer for analysis. The graphite crucible was made into a double crucible by inserting an inner crucible having a diameter of 10 mm and a height of 12 mm inside a diameter of 14 mm and a height of 20 mm. The analytical sample was dried at 110 ° C. for 2 hours to remove water, and then allowed to cool to room temperature in a desiccator. A 10 mg sample was weighed, sealed in a flux, compressed to sufficiently remove air, and subjected to analysis. The calibration curve was _{prepared from the analytical values of iron oxide (Fe 2} O ₃ ) (O: 30.06%) JSS-009-2 as a standard substance and the results of a blank test. It was measured and evaluated at a melting temperature of 3.4 kW (1634 ° C.) in an atmosphere of an inert gas (helium gas).

In addition, in the measurement of the atomic number ratio of each metal element in the general formula of the composite powder and the base particle, after drying the sample at 110 ° C. for 3 hours, 0.3 g is measured and pressurized with polytetrafluoroethylene. It was put into a container. To this, 10 ml of 24% by mass sulfuric acid was added, and the pressure vessel was put into the pressure decomposition apparatus. As the pressure decomposition apparatus, "Multiwave 7000" manufactured by Anton Pearl Japan was used, and the treatment was carried out at 230 ° C. and 15 atm for 24 hours. After the treatment, it was confirmed that the sample in the pressurized container was dissolved, and the content liquid and the washing liquid in the pressurized container were transferred to a plastic beaker and 100 ml was prepared with pure water. The atomic number ratio of each metal element was measured using "ICPE-9820" manufactured by Shimadzu Corporation for the constant volume solution.

Further, the composite powders in Samples 1 to 3, Samples 5 to 7, and Samples 9 to 26 using the reducing gas containing _{CO 2 gas are composed of BaCO 3} fine particles and predetermined transition metal fine particles on the surface of the base particles. And were deposited. Further, _{in the composite powders of Samples 4 and 8 using the reducing gas containing no CO 2} gas, predetermined transition metal fine particles were precipitated on the surface of the base particles. A high-resolution scanning transmission electron microscope and "JEM-ARM300F" manufactured by JEOL Ltd. were used as an energy dispersive X-ray spectroscope for measuring the average particle size of _{BaCO 3 fine particles and transition metal fine particles.} At this time, a methanol dispersion of the sample powder was dropped onto a copper microgrid, heated under vacuum, and dried. The magnification was set to 1 million times, and the particle size was measured.

Further, _{the analysis of the amount of BaCO 3} fine particles adhered (a value in the general formula of the composite powder) in the general formula of each oxide was specifically carried out as follows. After 1.0 g of the sample is placed in a platinum boat and set in a zirconia heating tube, the temperature is raised to 1500 ° C. at 10 ° C./min under a nitrogen 500 cm flow, and the outlet gas component during that period is CO by the non-dispersion infrared absorption method. _{2 This} was done by measuring with a concentration analyzer. As the CO ₂ concentration analyzer, "VA-3000" manufactured by HORIBA, Ltd. was used.

-Preparation of reforming catalyst for Sample 1C to Sample 3C-
In the preparation of the modified catalyst of Samples 1 to 26, CeO-ZrO powder, TiO ₂ powder, or Al ₂ O ₃ powder was used instead of the mixed powder, and heat treatment was performed in a reducing gas atmosphere. The modified catalysts of Samples 1C to 3C shown in Tables 1 and 2 described later were prepared in the same manner except for the points not found.

Tables 1 and 2 summarize the detailed configuration of the reforming catalyst of each sample. Tables 3 and 4 summarize the heat treatment conditions under a reducing gas atmosphere.

-Evaluation test-
The reforming catalyst of each sample was subjected to an activity test and a durability test of the steam reforming reaction.
Specifically, first, absolute ethanol and commercially available gasoline were mixed at a volume ratio of 20:80 to prepare an E20 fuel containing 20% by volume of absolute ethanol. _{Next, for a CO 2} (14%) / N ₂ mixed gas with a gas flow rate of 9.2 L / min, E20 fuel and ion-exchanged water were added to 1.35 mL / min and 1.09 mL / min using a liquid pump, respectively. By adding at a flow rate and vaporizing, a model gas as a base to be used in the activity test and the durability test was prepared. Further, as a gas for accelerating deterioration due to the sulfur component, a sulfur component-containing gas in which 100 ppm of _{sulfur dioxide (SO 2) was introduced into the model gas in terms of mass ratio was prepared.} The water vapor / carbon ratio (S / C) was 0.80, and the gas flow rate was 10.8 L / min.

Next, the reforming catalyst of each sample was filled in a stainless steel reaction tube having an inner diameter of 23.5 mm, and this reaction tube was mounted on a fixed bed flow type reaction apparatus. Next, as a pretreatment, the model gas was supplied to the reforming catalyst at a space velocity of about 60,000 hr- ¹ , and the catalyst bed temperatures were maintained at 400 ° C., 500 ° C., and 600 ° C. for about 1 hour, respectively. Then, as an activity test and a durability test, the catalyst bed temperature was set to 500 ° C. and held for 120 minutes. The concentration of hydrogen (H ₂ ) and carbon monoxide (CO) generated at that time was measured by gas chromatography to calculate the fuel reforming rate, and the change over time was investigated. The evaluation was performed every 30 minutes for 5 points at the start, the 30th minute, the 60th minute, the 90th minute, and the 120th minute. At this time, the evaluation up to the 60th minute was carried out with the above model gas, and the sulfur component-containing gas containing sulfur dioxide was introduced after the sampling at the 60th minute was completed. That is, the latter 60 minutes were evaluated with a sulfur-containing gas. Then, the rate of change was calculated from the following formula.
Rate of change [%] = 100 x (fuel reforming rate at start-fuel reforming rate at 120 minutes) / (fuel reforming rate at start)
When the rate of change was 30% or less, it was designated as A + because the effect of suppressing the deterioration of the catalytic performance over time due to the sulfur component contained in the fuel gas was high. When the rate of change was more than 30% and 40% or less, it was designated as A because it had an effect of suppressing deterioration of the catalyst performance over time due to the sulfur component contained in the fuel gas. When the rate of change was more than 40%, it was designated as C because there was no effect of suppressing the deterioration of the catalyst performance with time due to the sulfur component contained in the fuel gas. The results are summarized in Table 5.

According to Tables 1 to 5, the following can be seen.
The reforming catalysts of Samples 1C to 3C do not contain the composite powder specified in the present disclosure. Therefore, the catalyst performance deteriorated due to the sulfur component contained in the fuel gas. On the other hand, the reforming catalysts of Samples 1 to 26 contain the composite powder specified in the present disclosure, and thus the fuel gas. The catalytic performance was unlikely to deteriorate due to the sulfur component contained therein.

Further, when the reforming catalysts of Samples 1 to 26 are compared with each other, the following can be said. According to Samples 1 to 3, deterioration of catalyst performance due to the sulfur component can be suppressed even when the carriers are different. According to Samples 4 to 9, deterioration of the catalytic performance due to the sulfur component can be suppressed even when the degree of carbonation of BaO and the degree of oxidation of Co in the composite powder are different. Further, by changing the reduction treatment conditions, it is possible to change the degree of carbonation of BaO and the degree of oxidation of Co. According to Samples 10 to 14, even when the mass ratios of the composite powders are different, the deterioration of the catalytic performance due to the sulfur component can be suppressed. In particular, when the mass ratio of the composite powder is 20% or more and 80% or less, the catalytic function can be exhibited for a long time, and it becomes easy to suppress the time-dependent change of the fuel reforming rate. According to Samples 15 to 18, it is possible to change the average particle size _{of the BaCO 3 fine particles and the transition metal fine particles by changing the reduction treatment conditions.} According to Samples 19 to 26, even when the transition metal of M1 in the composite powder is replaced with the transition metal of M2 different from M1, the deterioration of the catalytic performance due to the sulfur component can be suppressed.

The present invention is not limited to each of the above-described embodiments and experimental examples, and various modifications can be made without departing from the gist thereof. In addition, each configuration shown in each embodiment and each experimental example can be arbitrarily combined.

1 Reform catalyst 10 Composite powder

Claims (11)

General formula: (BaO _1-a (CO ₃ ) _a ) YM1 _4-c M2 _c O _6-b (where 0 ≦ a ≦ 1, 0 ≦ b ≦ 4.5, 0 ≦ c <4) The reforming catalyst (1) containing the composite powder (10).
However, the above M1 and the above M2 are transition metals selected from the group consisting of Co, V, Cr, Mn, Fe, Ni, Cu, and Zn, respectively, so as to be different from each other. The above composite powder has a general formula: (BaO _1-a (CO ₃ ) _a ) YCo _4-c M2 _c O _6-b (provided that 0 ≦ a ≦ 1, 0 ≦ b ≦ 4.5, 0 ≦ c The reforming catalyst according to claim 1, which is represented by <4).
However, the above M2 is a transition metal selected from the group consisting of V, Cr, Mn, Fe, Ni, Cu, and Zn. The above-mentioned composite powder is represented by the general formula: (BaO _1-a (CO ₃ ) _a ) YCo ₄ O _6-b (where 0 ≦ a ≦ 1, 0 ≦ b ≦ 4.5). The reforming catalyst according to 1. The composite powder contains the _{base particles (101) represented by the general formula: BaYM1 4-c} M2 _c O _{7 + σ} (however, 0 ≦ c <4, 0 <σ ≦ 1.5) and the surface of the base particles. The first aspect of claim 1, wherein the BaCO ₃ fine particles (102) attached to the base particles and the transition metal fine particles (103) composed of at least one of the M1 fine particles and the M2 fine particles attached to the surface of the base particles are included. Modification catalyst.
However, the above M1 and the above M2 are transition metals selected from the group consisting of Co, V, Cr, Mn, Fe, Ni, Cu, and Zn, respectively, so as to be different from each other. The composite powder contains the _{base particles (101) represented by the general formula: BaYCo 4-c} M2 _c O _{7 + σ} (however, 0 ≦ c <4, 0 <σ ≦ 1.5) and the surface of the base particles. The second aspect of the present invention, which comprises the BaCO ₃ fine particles (102) attached to the base particles and the transition metal fine particles (103) composed of at least one of the Co fine particles and the M2 fine particles attached to the surface of the base particles. Modification catalyst.
However, the above M2 is a transition metal selected from the group consisting of V, Cr, Mn, Fe, Ni, Cu, and Zn. The composite powder includes base particles (101) represented by the general formula: BaYCo ₄ O _{7 + σ} (however, 0 <σ ≦ 1.5) and BaCO ₃ fine particles (102) adhering to the surface of the base particles. The reforming catalyst according to claim 3, further comprising transition metal fine particles (103) composed of Co fine particles adhering to the surface of the base particles. The _{modification according to any one of claims 4 to 6, wherein the average particle size of the BaCO 3} fine particles is 10 nm or more and 50 nm or less, and the average particle size of the transition metal fine particles is 0.5 nm or more and 30 nm or less. Quality catalyst. The modified catalyst according to any one of claims 1 to 7, which comprises a catalyst metal (11) and a carrier (12) supporting the catalyst metal. The reforming catalyst according to claim 8, wherein the weight ratio of the composite powder is 20% or more and 80% or less. General formula: _{A preparatory step for preparing at least a base particle powder represented by BaYM1 4-c} M2 _c O _{7 + σ} (where 0 ≦ c <4, 0 <σ ≦ 1.5).
By heat-treating at least the base particles powder in a reducing gas containing no in a reducing gas or CO ₂ containing CO _2, the general _{formula: (BaO 1-a (CO} 3) a) YM1 4-c M2 _{A production step for producing a composite powder represented by c} O _6-b (however, 0 ≦ a ≦ 1, 0 ≦ b ≦ 4.5, 0 ≦ c <4).
A method for producing a reforming catalyst.
However, the above M1 and the above M2 are transition metals selected from the group consisting of Co, V, Cr, Mn, Fe, Ni, Cu, and Zn, respectively, so as to be different from each other. The composite powder adhered to the base particles represented by the general formula: BaYM1 _4-c M2 _c O _{7 + σ} (however, 0 ≦ c <4, 0 <σ ≦ 1.5) and the surface of the base particles. The _{method for producing a modified catalyst according to claim 10, further comprising BaCO 3} fine particles and transition metal fine particles composed of at least one of M1 fine particles and M2 fine particles adhering to the surface of the base particles.
However, the above M1 and the above M2 are transition metals selected from the group consisting of Co, V, Cr, Mn, Fe, Ni, Cu, and Zn, respectively, so as to be different from each other.

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