KR100406366B1 - A method for manufacturing of high-temperature combustion catalyst of cation-substituted hexa-aluminate system - Google Patents

Abstract

The present invention relates to a method for producing a cationic substituted hexaaluminate catalyst for high temperature combustion, and its purpose is to form a substituted solid solution by replacing a cation with barium hexaaluminate in a composite oxide having a large specific surface area, thereby providing excellent hexa-hexahexane. An object of the present invention is to provide a method for obtaining an aluminate-based high temperature combustion catalyst.

The present invention for achieving the above object in the method for producing a hexaaluminate-based high temperature combustion catalyst, one or two or more salts selected from chromium salts, manganese salts, cobalt salts are prepared in an aqueous solution, respectively, barium After preparing an aqueous salt solution and a lanthanum salt solution and preparing gamma alumina, the aqueous solution and gamma alumina were converted to BaMAl ₁₁ O _19-α or Ba _1-x La _x MAl ₁₁ O _19-α (M is Cr, Mn, Co Cationic substituted barium hexaaluminate-based high temperature combustion catalyst, characterized in that the selected solid species or two or more, X is reacted to a composition of 0.2-0.5), impregnated and dried, and then heat treated at 1300 ° C. or more to obtain a substituted solid solution. The thing regarding a manufacturing method shall be the summary.

Description

Catalytic substituted hexaaluminate-based catalyst for high temperature combustion {A METHOD FOR MANUFACTURING OF HIGH-TEMPERATURE COMBUSTION CATALYST OF CATION-SUBSTITUTED HEXA-ALUMINATE SYSTEM}

The present invention relates to a method for producing a catalyst for high temperature combustion that can be used for catalytic combustion at a burner inlet, and more particularly, to produce a thermally stable catalyst for high temperature combustion by substituting a cation to form a hexaaluminate-based solid solution. It is about a method.

In the high temperature combustion catalyst, a typical conventional technique is to improve the heat resistance by adding a noble metal as an active ingredient to gamma alumina, but has some limitations. Therefore, metal oxides or composite oxides are excellent in heat resistance, so they are attempting to be applied as catalysts for high temperature combustion.

Perovskite-type oxides are known to have an oxidation catalyst activity interspersed with precious metals, but due to their poor thermal stability, development of related technologies for improving heat resistance is required.

Meanwhile, a complex of a metal or metal oxide including barium, calcium, magnesium and strontium of Group 2, and titanium and zirconium of Group 4A is primarily heat treated at 500 ° C. and heat treated at 1200 ° C. to maintain a specific surface area of 20 m 2 / g. A US patent (US 3,966,790) is proposed.

However, this invention has a problem that it cannot be applied at a high temperature of more than 1300 ℃.

The present invention takes into consideration that high temperature heat resistance of 1300 ° C. or higher is required when used as a catalyst material for high temperature combustion, and its purpose is barium hexaaluminate in a composite oxide having a large specific surface area because the specific surface area of the catalyst is directly connected to the heat resistance. It is to provide a method for obtaining a hexaaluminate-based high temperature combustion catalyst having excellent heat resistance by replacing a cation with a cation.

In addition, it is an object of the present invention to maintain the crystal structure of barium hexaaluminate by replacing Cr, Mn, Co in the cation instead of aluminum ions so that a large specific surface area is maintained at high temperature, and also barium in the cation substituted barium hexaaluminate Instead, by forming a lanthanum-substituted solid solution by substituting a part with lanthanum, it is to provide a method for obtaining a hexaaluminate-based high temperature combustion catalyst having excellent heat resistance.

1 is a flow chart schematically showing the process of producing a catalyst for high temperature combustion of the present invention

2 is a graph showing the change in specific surface area (m 2 / g) of hexaaluminate according to the amount of lanthanum substitution

The present invention for achieving the above object in the method for producing a hexaaluminate-based high temperature combustion catalyst, one or two or more salts selected from chromium salts, manganese salts, cobalt salts are prepared in an aqueous solution, respectively, barium After preparing an aqueous salt solution and preparing gamma alumina, the aqueous solution and gamma alumina were impregnated by reacting to form a composition of BaMAl ₁₁ O _19-α (M is one or more selected from Cr, Mn, and Co). Next, the present invention relates to a method for producing a cationic substituted barium hexaaluminate-based high temperature combustion catalyst, characterized in that a substituted solid is obtained by heat treatment at 1300 ° C. or higher.

In addition, the present invention is a method for producing a hexaaluminate-based high-temperature combustion catalyst, one or two or more salts selected from chromium salts, manganese salts, cobalt salts are prepared in an aqueous solution, respectively, barium salt solution and lanthanum After preparing an aqueous salt solution and preparing gamma alumina, these aqueous solutions and gamma alumina are Ba _1-x La _x MAl ₁₁ O _19-α (M is one or two or more selected from Cr, Mn, and Co), and X Is reacted to a composition having a value of 0.2-0.5, impregnated and dried, and then heat-treated at 1300 ° C. or more to provide a cationic substituted barium hexaaluminate-based catalyst for high temperature combustion.

Hereinafter, the present invention will be described in detail.

In the present invention, a chromium salt solution, a manganese salt solution, a cobalt salt solution, a barium salt solution, and gamma alumina are used as starting materials, and a lanthanum salt solution is used in the case of the lanthanum substitution type.

The chromium saline solution, manganese saline solution, cobalt saline solution can be used to select one kind, and can be used to select two or more kinds, the ratio is not a big problem when selecting two or more kinds.

The barium salt solution is for supplying barium ions, and the lanthanum salt solution is used to improve heat resistance by replacing with lanthanum ions instead of barium ions, and may control heat resistance by controlling the amount of substitution.

In addition, the brine solutions may take the usual salt form because the catalyst for high temperature combustion is prepared through pyrolysis, and examples thereof include hydrochloric acid, sulfuric acid, and nitrate.

The gamma alumina is conventional and preferably 99% or more in purity.

In the present invention, the reaction is carried out to the composition of BaMAl ₁₁ O _19-α or to the composition of Ba _1-x La _x MAl ₁₁ O _19-α (wherein M is one selected from Cr, Mn, and Co, or 2 or more types)

M is a transition metal, and one or two or more selected from Cr, Mn, and Co. The barium hexaaluminate substituted with Cr, Mn, and Co has a large specific surface area and is thermally stable at high temperature. This is substituted with aluminum ions of barium hexaaluminate (BaO · 6Al ₂ O ₃ ), and the size of ions is similar, and thermal stability is poor when elements such as Fe and Ni are substituted. In other words, the heat resistance of the substituted hexaaluminate crystal structure varies depending on the type of ion.

When the lanthanum is substituted in the barium site, the composition is Ba _1-x La _x MAl ₁₁ O _19-α , and X has a range of 0.2-0.5. If X is less than 0.2, the addition effect of lanthanum is insignificant, and if it exceeds 0.5, the specific surface area tends to decrease, which is not preferable.

In the present invention, impregnated and dried, and then heat treated at 1300 ° C. or higher to obtain a substituted solid solution.

If the heat treatment temperature is less than 1300 ℃ is not suitable for use as a catalyst for combustion above 1300 ℃.

The present invention relates to a method for producing a barium hexaaluminate-based high temperature combustion catalyst substituted with a cation.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

In this example, gamma alumina and water-soluble salts of metals as shown in Table 1 were prepared. Prepared gamma alumina and a water-soluble salt in the barium hexaaluminate composition so that the aluminum ion is replaced with a cation (M), that is, to have a composition of BaMAl ₁₁ O _19-α , respectively, according to the type of cation according to the method of the present invention Samples were prepared by heat treatment at 1300 ° C. for 2 hours. The specific surface area of the prepared sample was measured by the BET method and is shown in Table 1 below. It was also compared with barium hexaaluminate prepared by the same method.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Inventive Example 1 Inventive Example 2 Inventive Example 3 Substituted Cation (M) Al Ni Fe Cr Co Mn Specific surface area (㎡ / g) 16.2 12.2 13.2 17.3 15.1 14.8 % Of specific surface area (Comparative Example 1) 100 81 75 107 93 90

As can be seen from Table 1, Comparative Example 1 is a barium hexaaluminate, the specific surface area is 16.2 m 2 / g, and in the case of gamma alumina, it is known to be 1 m 2 / g or less. In case of substituted cations with Ni and Fe, Comparative Example 2-3 showed specific surface areas of 81% and 75% compared to those of Comparative Example 1, and barium hexaalumina substituted with Cr, Co, and Mn of Inventive Examples 1-3. Nate maintained a specific surface area of at least 90%. Therefore, in the present invention, it is preferable to prepare a substituted solid solution such that the composition of BaMAl ₁₁ O _19-α (M = Cr, Mn or Co) substituted with Cr, Co and Mn, including barium hexaaluminate, is preferred to maintain high temperature heat resistance. will be.

Example 2

In the present embodiment, the Ba _1-x La _x MAl ₁₁ O _19-α component is adjusted so that the aluminum ion is replaced with cation (M) and the part of barium ion is replaced by lanthanum in the barium hexaaluminate composition of gamma alumina. As shown in FIG. 2, the specific surface area of the sample prepared by changing the temperature from x = 0.1 to 0.8 and heat-treating at 1300 ° C. for 2 hours by the same process as that of FIG. 1 was measured.

In Fig. 2, when the amount of lanthanum addition is less than X = 0.2, the effect of the addition of lanthanum is not seen very much, and the specific surface area is remarkably large at X = 0.2-0.5. Therefore, it can be seen that the lanthanum content of the embodiment of the present invention is important and exerts the maximum effect at x = 0.2-0.5. Moreover, the specific surface area tends to decrease rather than x = 0.6. In the present invention, in the crystal structure of the cation-substituted barium hexaaluminate, lanthanum ions are added instead of barium ions to prepare Ba _1-x La _x MAl ₁₁ O _19-α (x = 0.2-0.5) in the preparation of the substituted solid solution. It is preferable to prepare a catalyst for high temperature combustion.

On the other hand, the catalytic combustion material of the present invention has a crystalline structure suitable for maintaining the specific surface area of the hexaaluminate of the composite oxide, it can be confirmed by electron microscopy having a layered structure in the form of a hexagonal plate. In the present invention, since the metal component is included by preparing a solid solution substituted with a cation, the activity of the catalyst can be expected, and due to the hexagonal plate structure, which is inherent in hexaaluminate, the specific surface area is large, and thus the heat resistance can be improved. Confirmed.

As described above, according to the present invention, by replacing the hexaaluminate crystal structure with a cation to prepare a substituted solid solution, it was possible to improve the heat resistance of the catalyst, and the amount of NOx generated by use in high temperature catalytic combustion of an industrial catalytic combustion device. The effect can be reduced and thermal efficiency can be increased. In addition, from the viewpoint of environmental conservation, catalytic combustion has an effect of preventing air pollution as an environmentally friendly energy conversion system.

Claims (4)

In the method for producing a hexaaluminate-based high temperature combustion catalyst, After preparing chromium salt in aqueous solution, preparing barium salt aqueous solution, preparing gamma alumina, impregnating and drying these aqueous solution and gamma alumina to a composition of BaCrAl ₁₁ O _19-α , and drying at 1300 ° C. or higher. A process for producing a cationic substituted barium hexaaluminate-based high temperature combustion catalyst, characterized in that a substituted solid solution is obtained by heat treatment. The method of claim 1, The salt is a method for producing a cationic substituted barium hexaaluminate-based high-temperature combustion catalyst, characterized in that selected from the form of hydrochloride, sulfate, nitrate. In the method for producing a hexaaluminate-based high temperature combustion catalyst, After preparing the chromium salt in the aqueous solution, preparing the barium salt solution and the lanthanum salt solution, and preparing gamma alumina, the aqueous solution and gamma alumina were Ba _1-x La _x CrAl ₁₁ O _19-α and X is 0.2. A method for producing a cationic substituted barium hexaaluminate catalyst for high temperature combustion, comprising reacting to a composition having a value of -0.5, impregnating and drying, and then performing heat treatment at 1300 ° C. or higher. The method of claim 3, wherein The salt is a method for producing a cationic substituted barium hexaaluminate-based high-temperature combustion catalyst, characterized in that selected from the form of hydrochloride, sulfate, nitrate.