JP2010131588A - Exhaust gas treatment catalyst and method of selecting the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas treatment catalyst which is a platinum alternating catalyst and makes combustion start temperature of a particulate substance equal to or lower than that of a platinum-based catalyst. <P>SOLUTION: The exhaust gas treatment catalyst promotes the combustion of the particulate substance contained in an exhaust gas and comprises AxByOz or AxByCwOz. The compopnent A is any one of a transition metal, bismuth or zinc, the component B is a transition metal, and the component C is any one of a transition metal or gallium. The band gap of the AxByOz or the AxByCwOz is equal to or lower than 3.0 eV, and oxygen orbital content of a conductor band obtained by numerically expressing contribution ratio of an oxygen atom to an electronic state is averagely equal to or higher than 20% with respect to three electronic states having low energy level right above a Fermi level in the band structure of the AxByOz or the AxByCwOz. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust gas treatment catalyst and a selection method thereof, and particularly to an exhaust gas treatment catalyst suitable for treatment of exhaust gas discharged from a diesel engine or the like and a selection method thereof.

  Exhaust gas discharged from a diesel engine or the like contains particulate matter (PM), and a diesel particulate filter (DPF) is used as a method for removing the particulate matter. In this DPF, PM in exhaust gas is captured, and the captured PM is burned and removed. As a catalyst for promoting the combustion of PM, various catalysts having platinum supported on a base material (hereinafter referred to as a platinum-based catalyst) have been developed. However, platinum itself is expensive, and the production cost of the catalyst is increased in proportion to the amount of platinum supported. For this reason, various research and developments have been conducted on catalysts with reduced platinum loading and platinum substitute catalysts in which a platinum substitute material is carried on a substrate.

As the platinum substitute catalyst described above, for example, Patent Document 1 proposes an exhaust gas treatment catalyst containing a composite oxide such as La ₂ CuO ₄ .

JP-A-5-184929 (see paragraphs [0038], [0042], etc. of the specification)

  Although the exhaust gas treatment catalyst containing the composite oxide promotes the combustion of particulate matter to lower the combustion start temperature of the particulate matter, it exhibits catalytic performance equivalent to or higher than the platinum-based catalyst described above. It was hoped to do.

  In developing an exhaust gas treatment catalyst containing the above-mentioned composite oxide, the target catalytic action (the temperature at which the combustion start temperature of the particulate matter is made equal to or lower than that of the platinum catalyst) In general, a method of selecting a substance that is expected to exhibit a catalytic ability) and confirming the catalytic action of the selected substance by an experiment is generally used. In such a method, the selection of the above-described substances depends on experience, and even the selected substances may not sufficiently exhibit the catalytic action, which requires a lot of labor.

  Therefore, the present invention has been proposed in view of the above-described problems, and is a platinum alternative catalyst, in which the combustion start temperature of the particulate matter is made equal to or lower than that of the platinum catalyst. An object is to provide an exhaust gas treatment catalyst.

  Moreover, it is a platinum alternative catalyst, and an exhaust gas treatment catalyst that expresses catalytic ability to make the combustion start temperature of the particulate matter equal or lower than that of the platinum catalyst is predicted with high accuracy. It is an object of the present invention to provide a method for selecting an exhaust gas treatment catalyst with reduced labor for selecting a substance that exhibits the catalytic ability.

The exhaust gas treatment catalyst according to the first invention for solving the above-described problem is
An exhaust gas treatment catalyst that promotes combustion of particulate matter contained in exhaust gas,
It consists of AxByOz or AxByCwOz,
A is any one of transition metal, bismuth or zinc,
B is a transition metal,
The C is one of a transition metal or gallium;
The band gap of the AxByOz or the AxByCwOz is 3.0 eV or less, and
In the band structure of the AxByOz or the AxByCwOz, the oxygen orbital content of the conduction band obtained by quantifying the contribution ratio of the oxygen atom to the electronic state by averaging the three electronic states having low energy ranks immediately above the Fermi level in the band structure of 20 % Or more.

The exhaust gas treatment catalyst according to the second invention for solving the above-described problem is
An exhaust gas treatment catalyst according to the first invention,
The AxByOz or the AxByCwOz has a structure excluding a perovskite type.

The exhaust gas treatment catalyst according to the third invention for solving the above-described problem is
An exhaust gas treatment catalyst according to the first or second invention,
A and B are zinc and manganese, cobalt and manganese, bismuth and molybdenum, nickel and chromium, iron and molybdenum, nickel and molybdenum, copper and chromium, copper and molybdenum, copper and tungsten, yttrium and ruthenium, holmium and manganese. Bismuth and silver, lanthanum and nickel, lanthanum and molybdenum, lanthanum and ruthenium, terbium and ruthenium, dysprosium and ruthenium, ytterbium and chromium, bismuth and cobalt, bismuth and nickel, bismuth and gold And

The exhaust gas treatment catalyst according to the fourth invention for solving the above-described problem is
An exhaust gas treatment catalyst according to the first or second invention,
The A, B, and C are any combination of lanthanum, cobalt, iridium, lanthanum, nickel, ruthenium, zinc, lanthanum, rhodium, zinc, lanthanum, iridium, bismuth, iron, gallium, bismuth, yttrium, and ruthenium. It is characterized by being.

The method for selecting an exhaust gas treatment catalyst according to the fifth invention for solving the above-described problem is as follows.
A method for selecting an exhaust gas treatment catalyst for selecting a candidate for an exhaust gas treatment catalyst comprising a composite oxide that promotes combustion of particulate matter contained in exhaust gas,
Obtaining the band structure of the composite oxide by scientific calculation,
Based on the band structure, the band gap is calculated,
The oxygen orbital content of the conduction band is calculated by averaging the contribution ratio of the oxygen atom to the electronic state by averaging the three electronic states having a low energy level immediately above the Fermi level in the band structure,
A candidate complex oxide is selected based on the oxygen orbital content of the band gap and the conduction band.

The method for selecting an exhaust gas treatment catalyst according to the sixth invention for solving the above-described problem is as follows.
A method for selecting an exhaust gas treatment catalyst according to a fifth invention,
The band structure of a known platinum-based catalyst and a known perovskite-type composite oxide is obtained by scientific calculation,
Based on the band structure, the band gap of the platinum-based catalyst and the perovskite complex oxide and the oxygen orbital content of the conduction band are calculated.
The candidate composite oxide is selected based on the band gap of the platinum-based catalyst and the perovskite-type composite oxide and the oxygen orbital content of the conduction band.

The method for selecting an exhaust gas treatment catalyst according to the seventh invention for solving the above-described problem is as follows.
A method for selecting an exhaust gas treatment catalyst according to the fifth or sixth invention,
Obtaining the band structure of the upward spin and the downward spin of the composite oxide by scientific calculation,
Calculate the band gap in the band structure of the upward spin and the band structure of the downward spin, respectively.
The candidate oxide is selected based on the smaller band gap by comparing the band gap of the upward spin and the band gap of the downward spin.

  According to the exhaust gas treatment catalyst of the present invention, it is a platinum substitute catalyst, and the combustion start temperature of the particulate matter can be made equal to or lower than that of the platinum-based catalyst.

  According to the method for selecting an exhaust gas treatment catalyst according to the present invention, it is a platinum substitute catalyst, and exhibits catalytic ability to make the combustion start temperature of the particulate matter equal to or lower than that of the platinum-based catalyst. Therefore, it is possible to predict the exhaust gas treatment catalyst to be performed with high accuracy, and to reduce labor for selecting a substance that exhibits the catalytic ability.

It is a graph which shows the relationship between the band gap and the oxygen orbital content rate of a conduction band in the exhaust gas treatment catalyst used by one Embodiment of the selection method of the exhaust gas treatment catalyst which concerns on this invention. It is a graph which shows the relationship between the band gap and the oxygen orbital content rate of a conduction band in the exhaust gas treatment catalyst used by one Embodiment of the selection method of the exhaust gas treatment catalyst which concerns on this invention. It is a graph which shows the relationship between the band gap and the oxygen orbital content rate of a conduction band in the exhaust gas treatment catalyst used by one Embodiment of the selection method of the exhaust gas treatment catalyst which concerns on this invention. It is a table | surface which shows the relationship between the band gap of the exhaust gas treatment catalyst which concerns on this invention, and the oxygen orbital content rate of a conduction band. It is a diagram showing the band structure of ZnMn ₂ O _4. It is a diagram showing the band structure of Co ₂ Mn ₃ O _8. Is a diagram showing the band structure of Bi ₂ MoO _6. Is a diagram showing the band structure of NiCrO _4. Is a diagram showing the band structure of _{Fe 2 (Mo 3 O 8)} , shows the case of an upward spin in FIG. 9 (a), shows the case of a downward spin in Figure 9 (b). Is a diagram showing the band structure of NiMoO _4, shows the case of a spin-up in FIG. 10 (a), shows the case of down spin in Figure 10 (b). Is a diagram showing the band structure of Cu (CrO _2), illustrates the case of an upward spin in FIG. 11 (a), shows the case of a downward spin in FIG 11 (b). Is a diagram showing the band structure of the CuMoO _4, shows the case of an upward spin in FIG. 12 (a), shows the case of a downward spin in Figure 12 (b). Is a diagram showing the band structure of Cu (WO _4), shows a case of an upward spin in FIG. 13 (a), shows the case of a downward spin in Figure 13 (b). Is a diagram showing the band structure of _{Y 2 (Ru 2 O 7)} , FIG. 14 (a) shows the case of spin up, showing a case of downward spin in FIG 14 (b). Is a diagram showing the band structure of Ho (Mn ₂ O _5), shows the case of a spin-up in FIG. 15 (a), shows the case of a downward spin in FIG 15 (b). Is a diagram showing the band structure of the Ag ₄ Bi ₂ O _5, shows the case of a spin-up in FIG. 16 (a), shows the case of a downward spin in FIG 16 (b). Is a diagram showing the band structure of Ag ₅ (BiO _4), shows a case of an upward spin in FIG. 17 (a), shows the case of a downward spin in FIG 17 (b). Is a diagram showing the band structure of La ₃ Ni ₂ O _6.35, FIG. 18 (a) shows the case of spin up, showing a case of downward spin in FIG 18 (b). La is a diagram showing the band structure of ₂ (Mo ₂ O _7), shows the case of a spin-up in FIG. 19 (a), shows the case of a downward spin in FIG 19 (b). La is a diagram showing the band structure of ₂ (RuO _5), shows the case of a spin-up in FIG. 20 (a), shows the case of a downward spin in FIG 20 (b). Is a diagram showing the band structure of _{Tb 2 (Ru 2 O 7)} , shows a case of an upward spin in FIG. 21 (a), shows the case of a downward spin in FIG 21 (b). Is a diagram showing the band structure of _{Dy 2 (Ru 2 O 7)} , shows the case of a spin-up in FIG. 22 (a), shows the case of a downward spin in FIG 22 (b). Is a diagram showing the band structure of Yb (CrO _4), shows a case of an upward spin in FIG. 23 (a), shows the case of a downward spin in FIG 23 (b). (Bi _12.24 Co _10.8) is a diagram showing the band structure of Co ₂ O _40, shows the case of a spin-up in FIG. 24 (a), shows the case of down spin in FIG 24 (b). (Bi _19.68 Ni _4.32) is a diagram showing the band structure of Ni ₂ O _40, shows the case of a spin-up in FIG. 25 (a), shows the case of a downward spin in FIG 25 (b). Is a diagram showing the band structure of Bi ₂ (AuO _5), shows the case of a spin-up in FIG. 26 (a), shows the case of a downward spin in FIG 26 (b). La is a diagram showing the band structure of ₂ (CoIrO _6), shows the case of a spin-up in FIG. 27 (a), shows the case of a downward spin in FIG 27 (b). Is a diagram showing the band structure of La ₂ NiRuO _6, shows the case of a spin-up in FIG. 28 (a), shows the case of a downward spin in FIG 28 (b). La is a diagram showing the band structure of ₂ Zn (RhO _6), shows the case of a spin-up in FIG. 29 (a), shows the case of a downward spin in FIG 29 (b). La is a diagram showing the band structure of ₂ (IrZnO _6), shows the case of a spin-up in FIG. 30 (a), shows the case of a downward spin in FIG 30 (b). Is a diagram showing the band structure of _{Bi 2 Ga 2 Fe 2 O 9} , shows the case of a spin-up in FIG. 31 (a), shows the case of a downward spin in FIG 31 (b). (Bi _0.2 Y _1.8) is a diagram showing the band structure of (Ru ₂ O _7), shows the case of a spin-up in FIG. 32 (a), shows the case of a downward spin in FIG 32 (b).

[Main embodiments]
Embodiments of an exhaust gas treatment catalyst and a selection method thereof according to the present invention will be described with reference to FIGS. 1, 2, 3, and 4.

  The exhaust gas treatment catalyst according to the present embodiment promotes combustion of particulate matter (PM) contained in exhaust gas discharged from a diesel engine or the like, and is composed of AxByOz or AxByCwOz, where A is a transition metal or bismuth. Or zinc, B is a transition metal, C is any one of transition metal or gallium, and the band gap of AxByOz or AxByCwOz is 3.0 eV or less, and In the band structure of the AxByOz or the AxByCwOz, the oxygen orbital content of the conduction band obtained by quantifying the contribution ratio of the oxygen atom to the electronic state by averaging the three electronic states having low energy ranks immediately above the Fermi level in the band structure of the AxByOz or the AxByCwOz It is 20% or more.

  In the exhaust gas treatment catalyst, the AxByOz or the AxByCwOz has a structure excluding a perovskite type.

  Specifically, A and B are zinc and manganese, cobalt and manganese, bismuth and molybdenum, nickel and chromium, iron and molybdenum, nickel and molybdenum, copper and chromium, copper and molybdenum, copper and tungsten, yttrium, and the like. Ruthenium, holmium and manganese, bismuth and silver, lanthanum and nickel, lanthanum and molybdenum, lanthanum and ruthenium, terbium and ruthenium, dysprosium and ruthenium, ytterbium and chromium, bismuth and cobalt, bismuth and nickel, bismuth and gold It is.

  The A, B, and C are any combination of lanthanum, cobalt, iridium, lanthanum, nickel, ruthenium, zinc, lanthanum, rhodium, zinc, lanthanum, iridium, bismuth, iron, gallium, bismuth, yttrium, and ruthenium. It is.

  According to such an exhaust gas treatment catalyst according to this embodiment, it is a platinum substitute catalyst, and the combustion start temperature of the particulate matter can be made equal to or lower than that of the platinum-based catalyst. it can. The reason will be described below.

  The band gap of the AxByOz or the AxByCwOz is a parameter that affects the PM combustion start temperature. When the band gap exceeds 3.0 eV, the PM combustion start temperature becomes higher than that of the platinum-based catalyst. 0.0 eV or less.

  The band gap described above is defined as the average value of one electronic state having the lowest energy level when the electron shell is Χ or Γ (gamma) in the conduction band, and the electron shell is 価 (chi) in the valence band. Alternatively, it is a value obtained by calculating the difference between the average values of one electronic state having the largest energy ranking in Γ (gamma). When there are a large number of bands near 0 eV, the AxByOz or the AxByCwOz is a conductor, and the band gap is 0.00 eV.

  The oxygen orbital content of the conduction band in the band structure of AxByOz or AxByCwOz is a parameter that affects the PM combustion rate. When it is less than 20%, the PM combustion rate is lower than that in the case of a platinum-based catalyst. Because it will be late, it is 20% or more. Note that the upper limit value of the oxygen orbital content of the conduction band of the composite oxide, in other words, the upper limit value of the index z is appropriately determined by the combination of A and B or the combination of A, B, and C. The

  Here, the oxygen orbital content of the above-described conduction band is obtained by averaging the three electronic states with low energy ranks immediately above the Fermi level in terms of energy and quantifying the contribution ratio of oxygen atoms to the electronic state. It is. The contribution ratio of oxygen atoms to the electronic state can be obtained by calculating how many electrons are included in a spherical surface containing oxygen atoms. When the AxByOz or AxByCwOz material is magnetic, the oxygen orbital content of the conduction band due to the upward spin band structure is used when selecting a candidate composite oxide. This is because the downward spin has fewer electrons than the upward spin, and some of the electronic states above the Fermi level in the downward spin band diagram may correspond to the valence band state of the upward spin. The valence band of an oxide mainly consists of orbital components of oxygen atoms. Therefore, if the orbit of oxygen is included in the state immediately above the band gap in the upward spin, it can be predicted that the orbit of oxygen atoms is also included in the state near the Fermi level of the downward spin.

  Subsequently, a method for selecting an exhaust gas treatment catalyst having the above-described composition, showing the range of the band gap described above, and indicating the range of the oxygen orbital content of the conduction band described above will be described below.

First, scientific calculation, for example, first-principles band calculation was performed on a platinum-based catalyst (for example, PtO, PtO _2, or Pt ₂ O ₃ ) that promotes the combustion of particulate matter contained in the exhaust gas. Based on this calculation result, the band structure of the platinum-based catalyst was obtained.

Subsequently, experimentally good catalytic ability, that is, a platinum substitute catalyst that can make the combustion start temperature of the particulate matter equal to or lower than that of the platinum catalyst can be confirmed. Catalysts (Mn-based perovskite type catalyst (for example, LaMnO ₃ doped with a small amount of potassium), Co-based perovskite type catalyst (for example, LaCoO ₃ doped with a small amount of potassium), and Fe-based perovskite A type catalyst (for example, LaFeO ₃ doped with a small amount of potassium) was modeled, and scientific calculations such as first-principles band calculations were performed. Based on the calculation results, band structures were determined for various catalysts (Mn-based perovskite-type catalyst, Co-based perovskite-type catalyst, and Fe-based perovskite-type catalyst).

Here, the above-described modeling is, for example, that a compound having a non-integer composition such as La _0.9 K _0.1 FeO ₃ is converted into an integer ratio of the composition such as LaFeO ₃ to obtain a structure capable of calculation. .

Further, a Cu-based perovskite-type catalyst (for example, a platinum substitute catalyst having a relatively low catalytic activity, which has a catalytic performance to increase the combustion start temperature of the particulate matter as compared with the case of a platinum-based catalyst (for example, For example, LaCuO ₃ doped with a small amount of potassium was also modeled, and scientific calculation, for example, first-principles band calculation was performed. Based on this calculation result, the band structure of the Cu-based perovskite catalyst was obtained.

  Subsequently, for each of the above-described catalysts (platinum-based catalyst, Mn-based perovskite-type catalyst, Co-based perovskite-type catalyst, Fe-based perovskite-type catalyst, and Cu-based perovskite-type catalyst), the oxygen orbital content of the band gap and conduction band Was calculated respectively.

  Subsequently, for each of the above-described catalysts (platinum-based catalyst, Mn-based perovskite-type catalyst, Co-based perovskite-type catalyst, Fe-based perovskite-type catalyst, and Cu-based perovskite-type catalyst), the oxygen orbital content of the band gap and conduction band. FIG. 1 which is a graph showing the correlation between the two is created. In FIG. 1, the square indicates the case of a Pt-based catalyst, the rhombus indicates the case of a Mn-based perovskite-type catalyst, the triangle indicates the case of a Co-based perovskite-type catalyst, and the round shape indicates the case of an Fe-based perovskite-type catalyst. The cross mark indicates the case of a Cu-based perovskite catalyst. As shown in FIG. 1, the Pt-based catalyst falls within the range of the region A, and the Mn-based perovskite-type catalyst, the Co-based perovskite-type catalyst, and the Fe-based perovskite-type catalyst substantially fall within the range of the region B, and the Cu-based perovskite-type catalyst. The catalyst was within range C.

Here, although the Pt-based catalyst has a high oxygen orbital content of the conduction band, it has a characteristic that the combustion start temperature of PM is higher than that of the Mn-based perovskite type catalyst (the catalytic ability is low). Are known. Therefore, it is considered that the narrow band gap is mainly a parameter related to the combustion start temperature of PM. Further, it is considered that the oxygen orbital content of the conduction band is a parameter related to the low temperature at the maximum CO ₂ concentration, that is, the PM combustion rate.

  It is known that the catalyst (Cu-based perovskite-type catalyst) entering the region C has a higher PM combustion start temperature than that of the Pt-based catalyst, and the PM combustion rate is lower than that of the Pt-based catalyst. . Therefore, the catalyst entering the region C can be classified into a low catalytic ability expression group that expresses catalytic ability in which the combustion start temperature of the particulate matter is higher than that of the Pt-based catalyst.

  In contrast, the catalyst entering the region B has a PM combustion start temperature equal to or lower than that of the Pt-based catalyst, and the PM combustion speed is faster than that of the Pt-based catalyst. It has been. Therefore, the catalyst entering the region B can be classified into a high catalytic ability expression group that expresses catalytic ability in which the combustion start temperature of the particulate matter is equal to or lower than that in the case of the Pt-based catalyst.

  Therefore, a compound having high catalytic ability, that is, a platinum substitute catalyst, and a composite oxidation that expresses catalytic ability to make the combustion start temperature of the particulate matter equal to or lower than that of the platinum-based catalyst. The product is considered to be mainly distributed in a region where the band gap is narrow and the oxygen band content of the conduction band is high.

Subsequently, 2,000 kinds of materials were extracted from the inorganic compound database, each material was modeled, and scientific calculation, for example, first principle band calculation was performed. Based on this calculation result, a band structure was obtained and a band gap was calculated. Of these materials, the oxygen orbital content of the conduction band described above was calculated for substances having a relatively narrow band gap. For these materials, FIG. 2 is created in which the band gap and the oxygen orbital content (screening data) of the conduction band are plotted on a graph showing the correlation between the bandgap and the oxygen orbital content of the conduction band. In FIG. 2, the rectangle indicates the case of screening data, the star I indicates the case of an exhaust gas treatment catalyst (ZnMn ₂ O ₄ ), and the star II indicates the case of an exhaust gas treatment catalyst (Co ₂ Mn ₃ O ₈ ). Asterisk III indicates an exhaust gas treatment catalyst (Bi ₂ MoO ₆ ), asterisk IV indicates an exhaust gas treatment catalyst (NiCrO ₄ ), and a cross indicates a reference catalyst (La ₂ CuO ₄ ). Show.

  From the above, regarding the composite oxide, it is considered that when the band gap is 3.0 eV or less, the effect that the combustion start temperature of PM becomes equal to or lower than that in the case of the Pt catalyst is exhibited. It is done. Furthermore, regarding the composite oxide, it is considered that the combustion rate of PM is equal to or faster than that of the Pt-based catalyst because the oxygen orbital content of the conduction band is 20% or more. In other words, with respect to the above-described exhaust gas treatment catalyst, as shown in FIG. 2, region D (region where the band gap is 0 eV or more and 3.0 eV or less and the oxygen band content of the conduction band is 20% or more) By using the composite oxide, it is considered that the combustion start temperature of PM can be made equal to or lower than that of the Pt-based catalyst. Furthermore, by using the above-described composite oxide, it is considered that the PM combustion rate can be made equal to or faster than that of the Pt-based catalyst.

In addition, magnetic materials other than NiCrO ₄ were modeled in the same manner as described above, and scientific calculations such as first-principles band calculations were performed. Based on the calculation results, the band structures of the upward spin and the downward spin were obtained, and the band gaps of the upward spin and the downward spin were calculated. In these materials, the band gap of the upward spin and the band gap of the downward spin were compared, and the oxygen orbital content of the conduction band was calculated for a material having a relatively narrow band gap. Here, as described above, when the band gap is 3.0 eV or less and the oxygen orbital content of the conduction band is 20% or more, the same effect as or more than that of the Pt-based catalyst is achieved. Since it is considered, the materials (Fe ₂ (Mo ₃ O ₈ ), NiMoO ₄ , satisfying these conditions (the band gap is 3.0 eV or less and the oxygen band content of the conduction band is 20% or more), Cu (CrO ₂ ), CuMoO ₄ , Cu (WO ₄ ), Y ₂ (Ru ₂ O ₇ ), Ho (Mn ₂ O ₅ ), Ag ₄ Bi ₂ O ₅ , Ag ₅ (BiO ₄ ), La ₃ Ni ₂ O _6.35 , La ₂ (Mo ₂ O ₇ ), La ₂ (RuO ₅ ), Tb ₂ (Ru ₂ O ₇ ), Dy ₂ (Ru ₂ O ₇ ), Yb (CrO ₄ ), (Bi _12.24 Co _10.8 ) Co ₂ O ₄₀ , (Bi _19.68 Ni _4.32 ) Ni ₂ O ₄₀ , Bi ₂ (A uO ₅ ), La ₂ (CoIrO ₆ ), La ₂ NiRuO ₆ , La ₂ Zn (RhO ₆ ), La ₂ (IrZnO ₆ ), Bi ₂ Ga ₂ Fe ₂ O ₉ , (Bi _0.2 Y _1.8 ) (Ru ₂ O ₇ )) is plotted in FIG. 3 and shown in FIG. In other words, regarding the above-described exhaust gas treatment catalyst, as shown in FIG. 3, region F (region where the band gap is 0 eV or more and 3.0 eV or less and the oxygen orbital content of the conduction band is 20% or more) By using the composite oxide, it is considered that the combustion start temperature of PM can be made equal to or lower than that of the Pt-based catalyst. Furthermore, by using the above-described composite oxide, it is considered that the PM combustion rate can be made equal to or faster than that of the Pt-based catalyst.

[Composite oxide of zinc and manganese]
Here, a composite oxide of zinc and manganese (ZnMn ₂ O ₄ ) will be specifically described with reference to FIG.
FIG. 5 is a diagram showing a band structure of ZnMn ₂ O ₄ . The band structure shown in FIG. 5 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 5, the vertical axis represents the energy state, and the horizontal axis represents each electron shell. In FIG. 5, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 5, a1 (thick line), a2 (one-dot chain line), and a3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band). In the region from the vicinity of the electron shell Δ to the vicinity of Λ, the one-dot chain line almost coincides with the thick line.

A composite oxide of zinc and manganese (ZnMn ₂ O ₄ ) is composed of AxByOz, wherein A is zinc and B is a transition metal.

In the composite oxide of zinc and manganese (ZnMn ₂ O ₄ ), as shown in FIG. 5, the region Ev below about −0.28 eV becomes a valence band, while the region Ec above about 0.8 eV It became a conduction band. The size of the forbidden band (band gap) Eg between these regions was about 1.08 eV.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of zinc and manganese is obtained by averaging the three electronic states (a1, a2, and a3) immediately above the Fermi level (conduction band). The percentage of contribution to the work was quantified and was 34%.

Therefore, as shown in FIG. 2, the composite oxide of zinc and manganese (ZnMn ₂ O ₄ ) has a band gap of 0 eV or more and 3.0 eV or less and an oxygen orbital content of the conduction band of 20% or more. It was confirmed to be within the range of the region D indicating a certain range. This composite oxide (ZnMn ₂ O ₄ ) has a structure excluding the perovskite type.

[Composite oxide of cobalt and manganese]
Here, a complex oxide of cobalt and manganese (Co ₂ Mn ₃ O ₈ ) will be specifically described with reference to FIG.
FIG. 6 is a diagram showing a band structure of Co ₂ Mn ₃ O ₈ . The band structure shown in FIG. 6 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 6, the vertical axis represents the energy state, and the horizontal axis represents each electron shell. In FIG. 6, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 6, b1 (thick line), b2 (one-dot chain line), and b3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

A complex oxide of cobalt and manganese (Co ₂ Mn ₃ O ₈ ) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

In the complex oxide of cobalt and manganese (Co ₂ Mn ₃ O ₈ ), as shown in FIG. 6, the region Ev below about −0.05 eV becomes the valence band, while the region above about 1.55 eV. Ec became the conduction band. The size of the forbidden band (band gap) Eg between these regions was about 1.60 eV.

  Further, the oxygen orbital content of the conduction band of the cobalt-manganese composite oxide averages the three states (b1, b2, b3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio of was quantified and was 31%.

Therefore, as shown in FIG. 2, the complex oxide of cobalt and manganese (Co ₂ Mn ₃ O ₈ ) has a band gap of 0 eV or more and 3.0 eV or less, and the oxygen orbital content of the conduction band is 20%. It was confirmed to be within the range of the region D indicating the above range. This composite oxide (Co ₂ Mn ₃ O ₈ ) has a structure excluding the perovskite type.

[Composite oxide of bismuth and molybdenum]
Here, a composite oxide of bismuth and molybdenum (Bi ₂ MoO ₆ ) will be specifically described with reference to FIG.
FIG. 7 is a diagram showing a band structure of Bi ₂ MoO ₆ . The band structure shown in FIG. 7 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 7, the vertical axis represents the energy state, and the horizontal axis represents each electron shell. In FIG. 7, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 7, c1 (thick line), c2 (one-dot chain line), and c3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

Bismuth and molybdenum complex oxide (Bi ₂ MoO ₆ ) is composed of AxByOz, wherein A is bismuth and B is a transition metal.

In the bismuth-molybdenum complex oxide (Bi ₂ MoO ₆ ), as shown in FIG. 7, the region Ev below about −0.4 eV becomes a valence band, while the region Ec above about 1.36 eV has a region Ec. It became a conduction band. The size of the forbidden band (band gap) Eg between these regions was about 1.76 eV.

  Further, the oxygen orbital content of the conduction band of the bismuth-molybdenum complex oxide averages the three states (c1, c2, c3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was 29%.

Therefore, the composite oxide of bismuth and molybdenum (Bi ₂ MoO ₆ ) has a band gap of 0 eV or more and 3.0 eV or less and an oxygen orbital content of the conduction band of 20% or more as shown in FIG. It was confirmed to be within the range of the region D indicating a certain range. This composite oxide (Bi ₂ MoO ₆ ) has a structure excluding the perovskite type.

[Complex oxide of nickel and chromium]
Here, the composite oxide of nickel and chromium (NiCrO ₄ ) will be specifically described with reference to FIG.
FIG. 8 is a diagram showing the band structure of NiCrO ₄ . The band structure shown in FIG. 8 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 8, the vertical axis represents the energy state, and the horizontal axis represents each electron shell. In FIG. 8, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 8, d1 (thick line), d2 (one-dot chain line), and d3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

The complex oxide of nickel and chromium (NiCrO ₄ ) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

As shown in FIG. 8, the composite oxide of nickel and chromium (NiCrO ₄ ) has a valence band in the region Ev below about −0.4 eV, and a conduction band in the region Ec above about 1.53 eV. It became. The size of the forbidden band (band gap) Eg between these regions was about 1.93 eV.

  Furthermore, the oxygen orbital content of the conduction band of the nickel-chromium composite oxide averages the three states (d1, d2, d3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and 28%.

Therefore, the composite oxide of nickel and chromium (NiCrO ₄ ) has a band gap of 0 eV or more and 3.0 eV or less and the oxygen band content of the conduction band is 20% or more as shown in FIG. It was confirmed to be within the range of the region D indicating This composite oxide (NiCrO ₄ ) has a structure excluding the perovskite type.

[Composite oxide of lanthanum and copper]
Here, the lanthanum and copper composite oxide (LaCuO ₄ ) will be described with reference to FIG.

The lanthanum and copper complex oxide (LaCuO ₄ ) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

Regarding the lanthanum and copper complex oxide (LaCuO ₄ ), the oxygen gap content of its band gap and conduction band was calculated by scientific calculation. This band gap was 1.47 eV. The oxygen band content of this conduction band was 19%.

Accordingly, as shown in FIG. 2, the lanthanum and copper composite oxide (LaCuO ₄ ) has a band gap of 0 eV or more and 3.0 eV or less and an oxygen orbital content of the conduction band of 20% or more. It was confirmed that it was out of the range of the region D showing

[Composite oxide of iron and molybdenum]
Here, a composite oxide of iron and molybdenum (Fe ₂ (Mo ₃ O ₈ )) will be described with reference to FIG.
The band structure shown in FIG. 9 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 9, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 9, A1 (thick line), A2 (one-dot chain line), and A3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

The complex oxide of iron and molybdenum (Fe ₂ (Mo ₃ O ₈ )) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

In the complex oxide of iron and molybdenum (Fe ₂ (Mo ₃ O ₈ )), as shown in FIG. 9B, there are many bands in the vicinity of 0 eV due to downward spin, so the size of the band gap Eg is small. It became 0.00 eV.

  Further, the oxygen orbital content of the conduction band of the composite oxide of iron and molybdenum is averaged from the three states (A1, A2, A3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was about 22%.

Therefore, as shown in FIG. 3, the complex oxide of iron and molybdenum (Fe ₂ (Mo ₃ O ₈ )) has a band gap of 3.0 eV or less and an oxygen band content of the conduction band of 20%. It was confirmed to be within the range of the region F indicating the above range. This composite oxide (Fe ₂ (Mo ₃ O ₈ )) has a structure excluding the perovskite type.

[Complex oxide of nickel and molybdenum]
Here, a composite oxide of nickel and molybdenum (NiMoO ₄ ) will be described with reference to FIG.
The band structure shown in FIG. 10 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 10, the vertical axis represents the energy state, and the horizontal axis represents each electron shell. In FIG. 10, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 10, B1 (thick line), B2 (one-dot chain line), and B3 (dotted line) indicate three electronic states with low energy orders immediately above the Fermi level (conduction band).

A composite oxide of nickel and molybdenum (NiMoO ₄ ) is a composite oxide made of AxByOz, where A is a transition metal and B is a transition metal.

In the composite oxide of nickel and molybdenum (NiMoO ₄ ), as shown in FIG. 10B, the region Ev below about 0 eV becomes a valence band, while the region Ec above about 0.60 eV has a conduction band. It became. The size of the forbidden band (band gap) Eg between these regions was 0.60 eV.

  Further, the oxygen orbital content of the conduction band of the nickel-molybdenum composite oxide averages the three states (B1, B2, B3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was quantified and was about 27%.

Therefore, the composite oxide of nickel and molybdenum (NiMoO ₄ ) shows a range in which the band gap is 3.0 eV or less and the oxygen orbital content of the conduction band is 20% or more, as shown in FIG. It was confirmed to be within the range of region F. This composite oxide (NiMoO ₄ ) has a structure excluding the perovskite type.

[Composite oxide of copper and chromium]
Here, a composite oxide of copper and chromium (Cu (CrO ₂ )) will be described with reference to FIG.
The band structure shown in FIG. 11 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 11, the vertical axis represents the energy state, and the horizontal axis represents each electron shell. In FIG. 11, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 11, C1 (thick line), C2 (one-dot chain line), and C3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

A complex oxide of copper and chromium (Cu (CrO ₂ )) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

As shown in FIG. 11, the composite oxide of copper and chromium (Cu (CrO ₂ )) has a region Ev below about −0.30 eV as a valence band, while a region Ec above about 1.80 eV. Became the conduction band. The size of the forbidden band (band gap) Eg between these regions was 2.10 eV.

  Furthermore, the oxygen orbital content of the conduction band of the complex oxide of copper and chromium averages the three states (C1, C2, C3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was about 22%.

Therefore, the composite oxide of copper and chromium (Cu (CrO ₂ )) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band of 20% or more as shown in FIG. It was confirmed to be within the range of the region F indicating the range. This composite oxide (Cu (CrO ₂ )) has a structure excluding the perovskite type.

[Composite oxide of copper and molybdenum]
Here, a composite oxide of copper and molybdenum (CuMoO ₄ ) will be described with reference to FIG.
The band structure shown in FIG. 12 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 12, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 12, D1 (thick line), D2 (one-dot chain line), and D3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

The complex oxide of copper and molybdenum (CuMoO ₄ ) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

As shown in FIG. 12B, the complex oxide of copper and molybdenum (CuMoO ₄ ) has many bands in the vicinity of 0 eV in the lower spin, so the band gap Eg becomes 0.00 eV. It was.

  Further, the oxygen orbital content of the conduction band of the composite oxide of copper and molybdenum is averaged from the three states (D1, D2, D3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was quantified and was about 27%.

Therefore, as shown in FIG. 3, the composite oxide of copper and molybdenum (CuMoO ₄ ) shows a range in which the band gap is 3.0 eV or less and the oxygen orbital content of the conduction band is 20% or more. It was confirmed to be within the range of region F. This composite oxide (CuMoO ₄ ) has a structure excluding the perovskite type.

[Composite oxide of copper and tungsten]
Here, a composite oxide of copper and tungsten (Cu (WO ₄ )) will be described with reference to FIG.
The band structure shown in FIG. 13 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 13, the vertical axis represents the energy state, and the horizontal axis represents each electron shell. In FIG. 13, E1 (thick line), E2 (one-dot chain line), and E3 (dotted line) indicate three electronic states having low energy orders immediately above the Fermi level (conduction band).

A complex oxide of copper and tungsten (Cu (WO ₄ )) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

As shown in FIG. 13B, the complex oxide of copper and tungsten (Cu (WO ₄ )) has a large number of bands in the vicinity of 0 eV in the lower spin, so the band gap size is 0.00 eV. It became.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of copper and tungsten is averaged from the three states (E1, E2, E3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was about 25%.

Therefore, as shown in FIG. 3, the composite oxide of copper and tungsten (Cu (WO ₄ )) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band of 20% or more. It was confirmed to be within the range of the region F indicating the range. This composite oxide (Cu (WO ₄ )) has a structure excluding the perovskite type.

[Compound oxide of yttrium and ruthenium]
Here, a composite oxide of yttrium and ruthenium (Y ₂ (Ru ₂ O ₇ )) will be described with reference to FIG.
The band structure shown in FIG. 14 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 14, the vertical axis represents the energy state, and the horizontal axis represents each electron shell. In FIG. 14, F1 (thick line), F2 (one-dot chain line), and F3 (dotted line) indicate three electronic states with low energy orders immediately above the Fermi level (conduction band).

The complex oxide of yttrium and ruthenium (Y ₂ (Ru ₂ O ₇ )) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

As shown in FIG. 14, the complex oxide of yttrium and ruthenium (Y ₂ (Ru ₂ O ₇ )) has a large number of bands in the vicinity of 0 eV in the lower spin, so the band gap size is 0.00 eV. It became.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of yttrium and ruthenium averages the three states (F1, F2, and F3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was about 26%.

Therefore, as shown in FIG. 3, the composite oxide of yttrium and ruthenium (Y ₂ (Ru ₂ O ₇ )) has a band gap of 3.0 eV or less and an oxygen band content of the conduction band of 20%. It was confirmed to be within the range of the region F indicating the above range. This composite oxide (Y ₂ (Ru ₂ O ₇ )) has a structure excluding the perovskite type.

[Composite oxide of holmium and manganese]
Here, a composite oxide of holmium and manganese (Ho (Mn ₂ O ₅ )) will be described with reference to FIG.
The band structure shown in FIG. 15 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 15, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 15, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 15, G1 (thick line), G2 (one-dot chain line), and G3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

A complex oxide of holmium and manganese (Ho (Mn ₂ O ₅ )) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

The composite oxide of holmium and manganese (Ho (Mn ₂ O ₅ )) has a valence band in the region Ev below about −1.00 eV, as shown in FIG. The upper region Ec became the conduction band. The size of the forbidden band (band gap) Eg between these regions was 1.00 eV.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of holmium and manganese is obtained by averaging the three states (G1, G2, G3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was about 29%.

Therefore, the composite oxide of holmium and manganese (Ho (Mn ₂ O ₅ )) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band of 20% or more as shown in FIG. It was confirmed that it was within the range of the region F indicating the range. This composite oxide (Ho (Mn ₂ O ₅ )) has a structure excluding the perovskite type.

[Composite oxide of bismuth and silver]
Here, a composite oxide of bismuth and silver (Ag ₄ Bi ₂ O ₅ ) will be described with reference to FIG.
The band structure shown in FIG. 16 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 16, the vertical axis represents the energy state, and the horizontal axis represents each electron shell. In FIG. 16, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 16, H1 (thick line), H2 (one-dot chain line), and H3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

A composite oxide of silver and bismuth (Ag ₄ Bi ₂ O ₅ ) is composed of AxByOz, wherein A is bismuth and B is a transition metal.

As shown in FIG. 16A, the bismuth-silver composite oxide (Ag ₄ Bi ₂ O ₅ ) has a valence band in the region Ev below about 0.00 eV, while it is above about 2.03 eV. The region Ec becomes a conduction band. The size of the forbidden band (band gap) Eg between these regions was 2.03 eV.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of bismuth and silver is obtained by averaging the three states (H1, H2, and H3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was about 29%.

Therefore, the composite oxide of bismuth and silver (Ag ₄ Bi ₂ O ₅ ) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band of 20% or more as shown in FIG. It was confirmed to be within the range of the region F indicating a certain range. This composite oxide ((Ag ₄ Bi ₂ O ₅ ) has a structure excluding the perovskite type.

[Composite oxide of bismuth and silver]
Here, a composite oxide of bismuth and silver (Ag ₅ (BiO ₄ )) will be described with reference to FIG.
The band structure shown in FIG. 17 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 17, the vertical axis represents the energy state, and the horizontal axis represents each electron shell. In FIG. 17, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 17, I1 (thick line), I2 (one-dot chain line), and I3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

Bismuth and silver complex oxide (Ag ₅ (BiO ₄ )) is composed of AxByOz, wherein A is bismuth and B is a transition metal.

As shown in FIG. 17A, the bismuth-silver composite oxide (Ag ₅ (BiO ₄ )) has a region Ev below about 0.00 eV serving as a valence band, while being above about 1.75 eV. The region Ec becomes a conduction band. The size of the forbidden band (band gap) Eg between these regions was 1.75 eV.

  Further, the oxygen orbital content of the conduction band of the composite oxide of bismuth and silver is obtained by averaging the three states (I1, I2, and I3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was about 28%.

Therefore, the composite oxide of bismuth and silver (Ag ₅ (BiO ₄ )) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band of 20% or more as shown in FIG. It was confirmed to be within the range of the region F indicating a certain range. This composite oxide ((Ag ₅ (BiO ₄ )) has a structure excluding the perovskite type.

[Composite oxide of lanthanum and nickel]
Here, a composite oxide of lanthanum and nickel (La ₃ Ni ₂ O _6.35 ) will be described with reference to FIG.
The band structure shown in FIG. 18 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 18, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 18, J1 (thick line), J2 (one-dot chain line), and J3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

A composite oxide of lanthanum and nickel (La ₃ Ni ₂ O _6.35 ) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

Since the lanthanum and nickel composite oxide (La ₃ Ni ₂ O _6.35 ) has many bands in the vicinity of 0 eV as shown in FIGS. 18A and 18B, the size of the band gap Eg is 0. It became 0.000V.

  Furthermore, the oxygen orbital content of the conduction band of the lanthanum-nickel composite oxide averages the three states (J1, J2, J3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was about 23%.

Therefore, the composite oxide of lanthanum and nickel (La ₃ Ni ₂ O _6.35 ) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band of 20% or more as shown in FIG. It was confirmed to be within the range of the region F indicating a certain range. This composite oxide (La ₃ Ni ₂ O _6.35 ) has a structure excluding the perovskite type.

[Composite oxide of lanthanum and molybdenum]
Here, a composite oxide of lanthanum and molybdenum (La ₂ (Mo ₂ O ₇ )) will be described with reference to FIG.
The band structure shown in FIG. 19 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 19, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 19, K1 (thick line), K2 (one-dot chain line), and K3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

A composite oxide of lanthanum and molybdenum (La ₂ (Mo ₂ O ₇ )) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

The composite oxide of lanthanum and molybdenum (La ₂ (Mo ₂ O ₇ )) has a large number of bands in the vicinity of 0 eV, as shown in FIGS. 19 (a) and 19 (b). It became 0.00 eV.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of lanthanum and molybdenum is obtained by averaging the three states (K1, K2, K3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was 20%.

Therefore, the composite oxide of lanthanum and molybdenum (La ₂ (Mo ₂ O ₇ )) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band of 20% as shown in FIG. It was confirmed to be within the range of the region F indicating the above range. This composite oxide (La ₂ (Mo ₂ O ₇ )) has a structure excluding the perovskite type.

[Composite oxide of lanthanum and ruthenium]
Here, a composite oxide of lanthanum and ruthenium (La ₂ (RuO ₅ )) will be described with reference to FIG.
The band structure shown in FIG. 20 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 20, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 20, L1 (thick line), L2 (one-dot chain line), and L3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

The complex oxide of lanthanum and ruthenium (La ₂ (RuO ₅ )) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

In the composite oxide of lanthanum and ruthenium (La ₂ (RuO ₅ )), as shown in FIG. 20B, there are many bands in the vicinity of 0 eV in the lower spin. It became 00 eV.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of lanthanum and ruthenium is obtained by averaging the three states (L1, L2, and L3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was about 29%.

Therefore, the composite oxide of lanthanum and ruthenium (La ₂ (RuO ₅ )) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band of 20% or more as shown in FIG. It was confirmed to be within the range of the region F indicating a certain range. This composite oxide (La ₂ (RuO ₅ )) has a structure excluding the perovskite type.

[Composite oxide of terbium and ruthenium]
Here, a composite oxide of terbium and ruthenium (Tb ₂ (Ru ₂ O ₇ )) will be described with reference to FIG.
The band structure shown in FIG. 21 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 21, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 21, M1 (thick line), M2 (one-dot chain line), and M3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

The complex oxide of terbium and ruthenium (Tb ₂ (Ru ₂ O ₇ )) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

In the complex oxide of terbium and ruthenium (Tb ₂ (Ru ₂ O ₇ )), as shown in FIG. 21B, there are many bands in the vicinity of 0 eV in the lower spin, so the band gap is large. It became 0.00 eV.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of terbium and ruthenium averages the three states (M1, M2, M3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was about 25%.

Therefore, as shown in FIG. 3, the terbium and ruthenium composite oxide (Tb ₂ (Ru ₂ O ₇ )) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band of 20%. It was confirmed to be within the range of the region F indicating the above range. This composite oxide (Tb ₂ (Ru ₂ O ₇ )) has a structure excluding the perovskite type.

[Composite oxide of dysprosium and ruthenium]
Here, a composite oxide of dysprosium and ruthenium (Dy ₂ (Ru ₂ O ₇ )) will be described with reference to FIG.
The band structure shown in FIG. 22 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 22, the vertical axis represents the energy state, and the horizontal axis represents each electron shell. In FIG. 22, N1 (thick line), N2 (one-dot chain line), and N3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

The complex oxide of dysprosium and ruthenium (Dy ₂ (Ru ₂ O ₇ )) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

In the complex oxide of dysprosium and ruthenium (Dy ₂ (Ru ₂ O ₇ )), as shown in FIG. 22 (b), there are many bands in the vicinity of 0 eV in the lower spin, so the band gap is large. It became 0.00 eV.

  Further, the oxygen orbital content of the conduction band of the composite oxide of dysprosium and ruthenium averages the three states (N1, N2, and N3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was about 25%.

Therefore, the composite oxide of dysprosium and ruthenium (Dy ₂ (Ru ₂ O ₇ )) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band of 20% as shown in FIG. It was confirmed to be within the range of the region F indicating the above range. This composite oxide (Dy ₂ (Ru ₂ O ₇ )) has a structure excluding the perovskite type.

[Compound oxide of ytterbium and chromium]
Here, a composite oxide of ytterbium and chromium (Yb (CrO ₄ )) will be described with reference to FIG.
The band structure shown in FIG. 23 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 23, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 23, O1 (thick line), O2 (one-dot chain line), and O3 (dotted line) indicate three electronic states having low energy ranks immediately above the Fermi level (conduction band).

A complex oxide of ytterbium and chromium (Yb (CrO ₄ )) is composed of AxByOz, wherein A is a transition metal and B is a transition metal.

As shown in FIG. 23B, the ytterbium-chromium complex oxide (Yb (CrO ₄ )) has many bands in the vicinity of 0 eV in the lower spin, so that the band gap size is 0.00 eV. It became.

  Furthermore, the oxygen orbital content of the conduction band of the complex oxide of ytterbium and chromium averages the three states (O1, O2, O3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio of was quantified and was about 21%.

Therefore, the composite oxide of ytterbium and chromium (Yb (CrO ₄ )) has a band gap of 3.0 eV or less and an oxygen band content of the conduction band of 20% or more as shown in FIG. It was confirmed to be within the range of the region F indicating the range. This composite oxide (Yb (CrO ₄ )) has a structure excluding the perovskite type.

[Composite oxide of bismuth and cobalt]
Here, a composite oxide of bismuth and cobalt ((Bi _12.24 Co _10.8 ) Co ₂ O ₄₀ ) will be described with reference to FIG.
The band structure shown in FIG. 24 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 24, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 24, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 24, P1 (thick line), P2 (one-dot chain line), and P3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

Bismuth and cobalt complex oxide ((Bi _12.24 Co _10.8 ) Co ₂ O ₄₀ ) is composed of AxByOz, wherein A is bismuth and B is a transition metal.

Bismuth and cobalt composite oxide ((Bi _12.24 Co _10.8 ) Co ₂ O ₄₀ ) has a valence band in the region Ev below about 0.00 eV, as shown in FIG. The region Ec above .43 eV became the conduction band. The size of the forbidden band (band gap) Eg between these regions was 1.43 eV.

  Furthermore, the oxygen orbital content of the conduction band of the bismuth-cobalt complex oxide averages the three states (P1, P2, P3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was quantified and was about 31%.

Therefore, the composite oxide of bismuth and cobalt ((Bi _12.24 Co _10.8 ) Co ₂ O ₄₀ ) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band as shown in FIG. It was confirmed to be within the range of the region F indicating the range of 20% or more. This composite oxide ((Bi _12.24 Co _10.8 ) Co ₂ O ₄₀ ) had a structure excluding the perovskite type.

[Composite oxide of bismuth and nickel]
Here, a composite oxide of bismuth and nickel ((Bi _19.68 Ni _4.32 ) Ni ₂ O ₄₀ ) will be described with reference to FIG.
The band structure shown in FIG. 25 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 25, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 25, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 25, Q1 (thick line), Q2 (one-dot chain line), and Q3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

Bismuth and nickel complex oxide ((Bi _19.68 Ni _4.32 ) Ni ₂ O ₄₀ ) is composed of AxByOz, wherein A is bismuth and B is a transition metal.

Bismuth and nickel composite oxide ((Bi _19.68 Ni _4.32 ) Ni ₂ O ₄₀ ) has a valence band in the region Ev below about 0.00 eV, as shown in FIG. The region Ec above 0.000 eV became the conduction band. The size of the forbidden band (band gap) Eg between these regions was 1.00 eV.

  Further, the oxygen orbital content of the conduction band of the composite oxide of bismuth and nickel is obtained by averaging the three states (Q1, Q2, Q3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was about 24%.

Therefore, the composite oxide of bismuth and nickel ((Bi _19.68 Ni _4.32 ) Ni ₂ O ₄₀ ) has a band gap of 3.0 eV or less and the oxygen band content of the conduction band as shown in FIG. It was confirmed to be within the range of the region F indicating the range of 20% or more. This composite oxide ((Bi _19.68 Ni _4.32 ) Ni ₂ O ₄₀ ) had a structure excluding the perovskite type.

[Composite oxide of bismuth and gold]
Here, a composite oxide of bismuth and gold (Bi ₂ (AuO ₅ )) will be described with reference to FIG.
The band structure shown in FIG. 26 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 26, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 26, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 26, R1 (thick line), R2 (one-dot chain line), and R3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

Bismuth and gold complex oxide (Bi ₂ (AuO ₅ )) is composed of AxByOz, wherein A is bismuth and B is a transition metal.

As shown in FIG. 26 (a), the bismuth-gold composite oxide (Bi ₂ (AuO ₅ )) has a valence band in the region Ev below about −0.20 eV, whereas from about 1.57 eV. The upper region Ec became the conduction band. The size of the forbidden band (band gap) Eg between these regions was 1.77 eV.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of bismuth and gold is obtained by averaging the three states (R1, R2, R3) immediately above the Fermi level (conduction band) to the electronic state of the oxygen atom. The contribution ratio was numerically and was about 47%.

Therefore, the composite oxide of bismuth and gold (Bi ₂ (AuO ₅ )) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band of 20% or more as shown in FIG. It was confirmed to be within the range of the region F indicating a certain range. This composite oxide (Bi ₂ (AuO ₅ )) has a structure excluding the perovskite type.

[Composite oxide of lanthanum, cobalt and iridium]
Here, a composite oxide of lanthanum, cobalt, and iridium (La ₂ (CoIrO ₆ )) will be described with reference to FIG.
The band structure shown in FIG. 27 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 27, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 27, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 27, S1 (thick line), S2 (one-dot chain line), and S3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

A composite oxide of lanthanum, cobalt, and iridium (La ₂ (CoIrO ₆ )) is composed of AxByCwOz, wherein A is a transition metal, B is a transition metal, and C is a transition metal. is there.

The composite oxide of lanthanum, cobalt, and iridium (La ₂ (CoIrO ₆ )) has a valence band in the region Ev below about 0.00 eV, as shown in FIG. The upper region Ec became the conduction band. The size of the forbidden band (band gap) Eg between these regions was 0.50 eV.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of lanthanum, cobalt, and iridium is obtained by averaging the three states (S1, S2, S3) immediately above the Fermi level (conduction band). The contribution to the state was quantified and was about 27%.

Therefore, the composite oxide of lanthanum, cobalt, and iridium (La ₂ (CoIrO ₆ )) has a band gap of 3.0 eV or less and an oxygen band content of the conduction band of 20% as shown in FIG. It was confirmed to be within the range of the region F indicating the above range. This composite oxide (La ₂ (CoIrO ₆ )) has a structure excluding the perovskite type.

[Composite oxide of lanthanum, nickel and ruthenium]
Here, a composite oxide (La ₂ NiRuO ₆ ) of lanthanum, nickel, and ruthenium will be described with reference to FIG.
The band structure shown in FIG. 28 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 28, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 28, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 28, T1 (thick line), T2 (one-dot chain line), and T3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

A composite oxide of lanthanum, nickel, and ruthenium (La ₂ NiRuO ₆ ) is composed of AxByCwOz, and is a composite oxide in which A is a transition metal, B is a transition metal, and C is a transition metal.

As shown in FIG. 28B, the composite oxide of lanthanum, nickel, and ruthenium (La ₂ NiRuO ₆ ) has a valence band in the region Ev below about 0.40 eV, while it is above about 0.80 eV. The region Ec becomes a conduction band. The size of the forbidden band (band gap) Eg between these regions was 0.40 eV.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of lanthanum, nickel, and ruthenium is obtained by averaging the three states (T1, T2, T3) immediately above the Fermi level (conduction band). The contribution to the state was quantified and was 20%.

Therefore, as shown in FIG. 3, the lanthanum, nickel, and ruthenium composite oxide (La ₂ NiRuO ₆ ) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band of 20% or more. It was confirmed to be within the range of the region F indicating a certain range. This composite oxide (La ₂ NiRuO ₆ ) has a structure excluding the perovskite type.

[Composite oxide of zinc, lanthanum and rhodium]
Here, a composite oxide of zinc, lanthanum, and rhodium (La ₂ Zn (RhO ₆ )) will be described with reference to FIG.
The band structure shown in FIG. 29 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 29, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 29, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 29, U1 (thick line), U2 (one-dot chain line), and U3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

A composite oxide of zinc, lanthanum, and rhodium (La ₂ Zn (RhO ₆ )) is composed of AxByCwOz, wherein A is zinc, B is a transition metal, and C is a transition metal. is there.

As shown in FIG. 29A, a composite oxide of zinc, lanthanum, and rhodium (La ₂ Zn (RhO ₆ )) has a valence band in the region Ev below about −0.20 eV. The region Ec above 0.03 eV became the conduction band. The size of the forbidden band (band gap) Eg between these regions was 2.23 eV.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of zinc, lanthanum, and rhodium averages the electrons of oxygen atoms by averaging the three states (U1, U2, U3) immediately above the Fermi level (conduction band). The contribution to the state was quantified and was about 34%.

Therefore, as shown in FIG. 3, the composite oxide of zinc, lanthanum, and rhodium (La ₂ Zn (RhO ₆ )) has a band gap of 3.0 eV or less and an oxygen orbital content of a conduction band of 20 % Was confirmed to be within the range of the region F indicating the range of at least%. This composite oxide (La ₂ Zn (RhO ₆ )) has a structure excluding the perovskite type.

[Composite oxide of zinc, lanthanum and iridium]
Here, a composite oxide of zinc, lanthanum, and iridium (La ₂ (IrZnO ₆ )) will be described with reference to FIG.
The band structure shown in FIG. 30 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 30, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 30, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 30, V1 (thick line), V2 (one-dot chain line), and V3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

A composite oxide of zinc, lanthanum, and iridium (La ₂ (IrZnO ₆ )) is a composite oxide composed of AxByCwOz, where A is zinc, B is a transition metal, and C is a transition metal.

As shown in FIG. 30 (a), a composite oxide of zinc, lanthanum, and iridium (La ₂ (IrZnO ₆ )) has a valence band in the region Ev below about −0.15 eV, whereas it is about 2.00 eV. The upper region Ec became the conduction band, and the size of the forbidden band (band gap) Eg between these regions was 2.15 eV.

  Further, the oxygen orbital content of the conduction band of the composite oxide of zinc, lanthanum, and iridium is obtained by averaging the three states (V1, V2, and V3) immediately above the Fermi level (conduction band). The contribution to the state was quantified and was about 34%.

Therefore, as shown in FIG. 3, the composite oxide of zinc, lanthanum, and iridium (La ₂ (IrZnO ₆ ) has a band gap of 3.0 eV or less and the oxygen band content of the conduction band is 20% or more. The composite oxide (La ₂ (IrZnO ₆ )) has a structure excluding the perovskite type.

[Composite oxide of bismuth, iron and gallium]
Here, a composite oxide of bismuth, iron, and gallium (Bi ₂ Ga ₂ Fe ₂ O ₉ ) will be described with reference to FIG.
The band structure shown in FIG. 31 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 31, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 31, Ec represents a conduction band, Ev represents a valence band, and Eg represents a forbidden band. In FIG. 31, W1 (thick line), W2 (one-dot chain line), and W3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

A composite oxide of bismuth, iron and gallium (Bi ₂ Ga ₂ Fe ₂ O ₉ ) is composed of AxByCwOz, wherein A is bismuth, B is a transition metal, and C is gallium. is there.

The composite oxide of bismuth, iron and gallium (Bi ₂ Ga ₂ Fe ₂ O ₉ ) has many bands in the vicinity of 0 eV due to upward spin as shown in FIG. Became 0.00 eV.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of bismuth, iron, and gallium is obtained by averaging the three states (W1, W2, W3) immediately above the Fermi level (conduction band). The contribution rate to the state was quantified and was about 24%.

Therefore, the composite oxide of bismuth, iron, and gallium (Bi ₂ Ga ₂ Fe ₂ O ₉ ) has a band gap of 3.0 eV or less and an oxygen orbital content of the conduction band as shown in FIG. It was confirmed to be within the range of the region F indicating the range of 20% or more. This composite oxide (Bi ₂ Ga ₂ Fe ₂ O ₉ ) has a structure excluding the perovskite type.

[Composite oxide of bismuth, yttrium, and ruthenium]
Here, a composite oxide of bismuth, yttrium, and ruthenium ((Bi _0.2 Y _1.8 ) (Ru ₂ O ₇ )) will be described with reference to FIG.
The band structure shown in FIG. 32 is a band structure obtained by band calculation (for example, first principle band calculation). In FIG. 32, the vertical axis indicates the energy state, and the horizontal axis indicates each electron shell. In FIG. 32, X1 (thick line), X2 (one-dot chain line), and X3 (dotted line) indicate three electronic states with low energy ranks immediately above the Fermi level (conduction band).

The composite oxide of bismuth, yttrium, and ruthenium ((Bi _0.2 Y _1.8 ) (Ru ₂ O ₇ )) is made of AxByCwOz, the A is bismuth, the B is a transition metal, and the C is a transition metal. It is a complex oxide.

The composite oxide of bismuth, yttrium, and ruthenium ((Bi _0.2 Y _1.8 ) (Ru ₂ O ₇ )) has many bands near 0 eV in the lower spin, as shown in FIG. The size of the band gap Eg was 0.00 eV.

  Furthermore, the oxygen orbital content of the conduction band of the composite oxide of bismuth, yttrium, and ruthenium is obtained by averaging the three states (X1, X2, and X3) immediately above the Fermi level (conduction band). The contribution rate to the state was quantified and was about 25%.

Therefore, the composite oxide of bismuth, yttrium, and ruthenium ((Bi _0.2 Y _1.8 ) (Ru ₂ O ₇ )) has a band gap of 3.0 eV or less and oxygen in the conduction band as shown in FIG. It was confirmed that the content of the orbit was within the range of the region F indicating the range of 20% or more. This composite oxide (Bi _0.2 Y _1.8 ) (Ru ₂ O ₇ )) has a structure excluding the perovskite type.

[Preparation method of composite oxide]
Complex oxides mentioned above (zinc and manganese complex oxide, cobalt and manganese complex oxide, bismuth and molybdenum complex oxide, nickel and chromium complex oxide, iron and molybdenum complex oxide, nickel and molybdenum complex oxide Complex oxides, complex oxides of copper and chromium, complex oxides of copper and molybdenum, complex oxides of copper and tungsten, complex oxides of yttrium and ruthenium, complex oxides of holmium and manganese, complex oxides of bismuth and silver Lanthanum and nickel composite oxide, lanthanum and molybdenum composite oxide, lanthanum and ruthenium composite oxide, terbium and ruthenium composite oxide, dysprosium and ruthenium composite oxide, ytterbium and chromium composite oxide, Bismuth and cobalt composite oxide, bismuth and nickel composite oxide, bis Composite oxide of lanthanum, cobalt and iridium, composite oxide of lanthanum, nickel and ruthenium, composite oxide of zinc, lanthanum and rhodium, composite oxide of zinc, lanthanum and iridium, bismuth and Complex oxide of iron and gallium, complex oxide of bismuth, yttrium and ruthenium), oxide, hydroxide, carbonate, nitrate, sulfate, acetate, oxalate or chloride of each metal element It can be prepared by mixing at a predetermined ratio and finally baking at 600 to 1000 ° C., preferably 700 to 900 ° C. for about 2 to 10 hours.

  As a method for mixing each metal element salt, a method in which each metal salt is mixed in a solid state, a method in which each metal salt solution (such as an aqueous solution) is mixed and then evaporated to dryness, and each metal salt is mixed. A coprecipitation method in which the solution is hydrolyzed with an alkaline solution such as aqueous ammonia can be used. Specifically, a solid phase method by ball mill mixing, a coprecipitation method, a thermal decomposition method, or the like can be employed.

For example, in preparing a composite oxide of zinc and manganese (ZnMn ₂ O ₄ ), zinc oxide and manganese oxide are prepared as raw materials. The powders are temporarily mixed at such a ratio that these raw materials can be obtained by stoichiometry. Further, a solvent (ethanol, dispersant, etc.) is added and mixed for 20 hours with a ball mill. Thereafter, the composite oxide can be obtained by drying at 120 ° C. and firing at 850 ° C. for 10 hours.

  Therefore, according to the method for selecting an exhaust gas treatment catalyst according to the present embodiment, the band structure of the composite oxide is obtained by scientific calculation, the band gap is calculated based on the band structure, and immediately above the Fermi level in the band structure. The oxygen band orbital content of the conduction band is calculated by averaging the three electronic states having low energy ranks at, and quantifying the contribution ratio of oxygen atoms to the electronic state. A catalyst that is a platinum substitute catalyst by selecting candidate composite oxides based on the content rate, and makes the combustion start temperature of particulate matter equal to or lower than that of platinum-based catalysts Therefore, it is possible to predict an exhaust gas treatment catalyst exhibiting high performance with high accuracy, and to reduce labor for selecting a substance that exhibits the catalytic performance.

  Furthermore, the band structure of the known platinum-based catalyst and the known perovskite-type composite oxide is obtained by scientific calculation. Based on the band structure, the band gap and conduction of the platinum-based catalyst and the perovskite-type composite oxide are determined. Calculate the oxygen orbital content of the band and select the candidate composite oxide based on the bandgap and the oxygen orbital content of the conduction band of the platinum-based catalyst and the perovskite-type composite oxide. Thus, a high catalytic activity expression group that exhibits catalytic ability in which the combustion start temperature of the particulate matter is equal to or lower than that of the platinum-based catalyst, and the combustion start temperature of the particulate matter is the platinum-based material. It can be classified into low catalytic ability expression group that expresses higher catalytic ability compared to the case of catalyst, platinum catalyst and high catalytic ability Regard the current group and the low catalytic activity expression group obtains a distribution of oxygen trajectory content of conduction band and the band gap, it is possible to select a composite oxide having a candidate on the basis of this distribution. Therefore, an exhaust gas treatment catalyst that is a platinum substitute catalyst and that exhibits catalytic ability to make the combustion start temperature of the particulate matter equal to or lower than that of the platinum catalyst is predicted with higher accuracy. Thus, it is possible to reduce labor for selecting a substance that exhibits the catalytic ability.

  Further, the upward spin and the downward spin band structures of the composite oxide are respectively obtained by scientific calculation, and the band gaps of the upward spin band structure and the downward spin band structure are calculated, respectively. By selecting a candidate composite oxide based on the smaller band gap compared to the band gap of the downward spin, even if the composite oxide is a magnetic substance, it is a platinum substitute catalyst. , A substance that expresses the exhaust gas treatment catalyst that expresses the catalytic ability to make the combustion start temperature of the particulate matter equal to or lower than that of the platinum-based catalyst with high accuracy, and expresses the catalytic ability Can reduce the labor of selecting.

  Although the confirmation test performed in order to confirm the effect of the exhaust gas treatment catalyst according to the present invention will be described below, the present invention is not limited only to the confirmation test described below.

[Preparation of specimen]
In order to confirm the relationship between the composition of the exhaust gas treatment catalyst (composite oxide) and the combustion start temperature, the composite oxide of ZnMn ₂ O ₄ is used based on the composite oxide preparation method described in the above embodiment. A catalyst (test body 1), a catalyst (test body 2) made of a composite oxide of Co ₂ Mn ₃ O ₈ , a catalyst (test body 3) made of a composite oxide of Bi ₂ MoO _{6, and} a composite of NiCrO ₄ An oxide catalyst (test body 4) was prepared. As reference examples, a sample without a catalyst (reference test sample 1) and an Al ₂ O ₃ base material carrying Pt (reference test sample 2) were also produced.

[Test method]
In this test, the smoke combustion activity was evaluated based on the combustion start temperature of black smoke. A mixed sample in which activated carbon powder imitating black smoke and a catalyst is mixed, the mixed sample is heated under a predetermined gas flow, the generated CO ₂ is regarded as a combustion reaction, and the CO ₂ production start temperature is set to a fine particle. The temperature was evaluated as the combustion start temperature of the particulate material. The combustion start temperature was obtained by extrapolating the slope of the region where the CO ₂ concentration is stored in the CO ₂ temperature distribution to the temperature axis. The generated gas was analyzed by continuously measuring the CO, CO ₂ and NOx concentrations.

Specifically, the catalyst powder (test body 1 described above) was mixed with 5 wt% of commercially available activated carbon powder (manufactured by Wako), a small amount of alcohol was added, and the mixture was thoroughly stirred and mixed in an agate mortar and then dried at 60 ° C. Let A sample diluted to about 50 wt% with classified SiO ₂ powder is loaded into a fixed bed flow microreactor, and the temperature and generation are analyzed while raising the temperature under the flow of gas (temperature rising reaction method). The black smoke combustion performance was evaluated by investigating the gas correlation. The evaluation conditions at this time are shown in Table 1 below. For specimens 2, 3, 4 and reference specimen 2, samples were prepared in the same manner as in specimen 1 described above, and these specimens were also the same as in specimen 1 described above. Each method was evaluated. For Reference Specimen 1, a small amount of alcohol was added to 5 wt% of commercially available activated carbon powder (manufactured by Wako Co., Ltd.), stirred and mixed well in an agate mortar, dried at 60 ° C., and approximately 50 wt% with classified SiO ₂ powder. A sample diluted to 1 was prepared, and this sample was evaluated in the same manner as in the case of the specimen 1 described above.

[Test results]
The results evaluated under the conditions in Table 1 above are shown in Table 2 below.

As shown in Table 2 above, it was revealed that in the specimen 1 (ZnMn ₂ O ₄ ), which is a composite oxide of zinc and manganese, the combustion start temperature of activated carbon was 270 ° C. In the specimen 2 (Co ₂ Mn ₃ O ₈ ), which is a complex oxide of cobalt and manganese, it became clear that the combustion start temperature of the activated carbon was 272 ° C. In the specimen 3 (Bi ₂ MoO ₆ ), which is a composite oxide of bismuth and molybdenum, it became clear that the combustion start temperature of the activated carbon was 280 ° C. In the specimen 4 (NiCrO ₄ ), which is a composite oxide of nickel and chromium, it became clear that the combustion start temperature of activated carbon was 285 ° C.

Moreover, in the reference test body 1 without a catalyst, it became clear that the combustion start temperature of activated carbon is 434 degreeC. In Reference Specimen 2 (Pt / Al ₂ O ₃ ), which is a platinum-based catalyst with platinum supported on alumina, it became clear that the combustion start temperature of activated carbon was 285 ° C.

That is, it was confirmed that in the test body 1 (ZnMn ₂ O ₄ ), the combustion start temperature of the activated carbon is lower than that in the case of the reference test body 2 (Pt / Al ₂ O ₃ ). In the test body 2 (CoMn ₃ O ₈ ), it was confirmed that the combustion start temperature of the activated carbon was lower than that in the case of the reference test body 2 (Pt / Al ₂ O ₃ ). In the test body 3 (Bi ₂ MoO ₆ ), it was confirmed that the combustion start temperature of the activated carbon was lower than that in the case of the reference test body 2 (Pt / Al ₂ O ₃ ). In the specimen 4 (NiCrO ₄ ), it was confirmed that the combustion start temperature of the activated carbon was equivalent to that in the case of the reference specimen 2 (Pt / Al ₂ O ₃ ).

Therefore, according to the test bodies 1, 2, 3, and 4 of the composite oxide, it is a platinum substitute catalyst, and the combustion start temperature of the activated carbon is equivalent to that of the reference test body 2 (Pt / Al ₂ O ₃ ). It was confirmed that it can be lower or lower.

  The exhaust gas treatment catalyst and the selection method thereof according to the present invention can be used for an exhaust gas treatment catalyst for treating exhaust gas discharged from an automobile or a plant, a selection method thereof, and the like.

Claims (7)

An exhaust gas treatment catalyst that promotes combustion of particulate matter contained in exhaust gas,
It consists of AxByOz or AxByCwOz,
A is any one of transition metal, bismuth or zinc,
B is a transition metal,
The C is one of a transition metal or gallium;
The band gap of the AxByOz or the AxByCwOz is 3.0 eV or less, and
In the band structure of the AxByOz or the AxByCwOz, the oxygen orbital content of the conduction band obtained by quantifying the contribution ratio of the oxygen atom to the electronic state by averaging the three electronic states having low energy ranks immediately above the Fermi level in the band structure of 20 Exhaust gas treatment catalyst characterized by being at least%. An exhaust gas treatment catalyst according to claim 1,
The exhaust gas treatment catalyst, wherein the AxByOz or the AxByCwOz has a structure excluding a perovskite type. An exhaust gas treatment catalyst according to claim 1 or claim 2,
A and B are zinc and manganese, cobalt and manganese, bismuth and molybdenum, nickel and chromium, iron and molybdenum, nickel and molybdenum, copper and chromium, copper and molybdenum, copper and tungsten, yttrium and ruthenium, holmium and manganese. Bismuth and silver, lanthanum and nickel, lanthanum and molybdenum, lanthanum and ruthenium, terbium and ruthenium, dysprosium and ruthenium, ytterbium and chromium, bismuth and cobalt, bismuth and nickel, bismuth and gold Exhaust gas treatment catalyst. An exhaust gas treatment catalyst according to claim 1 or claim 2,
The A, B, and C are any combination of lanthanum, cobalt, iridium, lanthanum, nickel, ruthenium, zinc, lanthanum, rhodium, zinc, lanthanum, iridium, bismuth, iron, gallium, bismuth, yttrium, and ruthenium. An exhaust gas treatment catalyst characterized by A method for selecting an exhaust gas treatment catalyst for selecting a candidate for an exhaust gas treatment catalyst comprising a composite oxide that promotes combustion of particulate matter contained in exhaust gas,
Obtaining the band structure of the composite oxide by scientific calculation,
Based on the band structure, the band gap is calculated,
The oxygen orbital content of the conduction band is calculated by averaging the contribution ratio of the oxygen atom to the electronic state by averaging the three electronic states having a low energy level immediately above the Fermi level in the band structure,
A method for selecting an exhaust gas treatment catalyst, comprising selecting a candidate complex oxide based on the oxygen orbital content of the band gap and the conduction band. A method for selecting an exhaust gas treatment catalyst according to claim 5,
The band structure of a known platinum-based catalyst and a known perovskite-type composite oxide is obtained by scientific calculation,
Based on the band structure, the band gap of the platinum-based catalyst and the perovskite complex oxide and the oxygen orbital content of the conduction band are calculated.
A method for selecting an exhaust gas treatment catalyst, wherein the candidate composite oxide is selected based on the band gap of the platinum-based catalyst and the perovskite-type composite oxide and the oxygen orbital content of the conduction band. . A method for selecting an exhaust gas treatment catalyst according to claim 5 or 6,
Obtaining the band structure of the upward spin and the downward spin of the composite oxide by scientific calculation,
Calculate the band gap in the band structure of the upward spin and the band structure of the downward spin, respectively.
A method for selecting an exhaust gas treatment catalyst, wherein the candidate composite oxide is selected based on a smaller band gap by comparing the band gap of the upward spin and the band gap of the downward spin.

Images