JPS60166038A - Manufacture of oxidizing catalyst for catalytic combustion - Google Patents

Abstract

PURPOSE:To obtain a highly active oxidizing catalyst consisting of a composite metal oxide which has perovskite structure of large surface area by depositing various mixed salts soln. of prescribed ratio quantities on activated carbon and thereafter drying and calcining said activated carbon. CONSTITUTION:In case of adjusting an oxidizing catalyst for catalytic combustion consisting of a composite metal oxide provided with perovskite structure wherein in the crystal structures A1-xA'xB1-yB'yO3, A and A' are rare earth elements such as La and Ce or an element selected from the elements whose ion radiuses are >=0.90Angstrom among alkaline earth metals such as Sr and Ca, and x is number of 0-1.0 range and B, B' are an element selected from the elements whose ion radiuses are >=0.51Angstrom among transition-metallic elements such as Co, Fe, Ni and Mn and y has number of 0-1.0 range, a mixed soln. consisting of one kind of common salt among various salts such as nitrate and acetate of the prescribed ratio quantity is deposited at once the activated carbon and thereafter the activated carbon is dried and calcined. As a result, the oxidizing catalyst having a large surface area and high activity is obtained.

Description

Detailed Description of the Invention: Industrial Application Field The present invention provides a catalytic combustor that catalytically combusts a relatively light hydrocarbon gas such as natural gas or propane gas on an oxidation catalyst mat, and utilizes the heat generated at the time. The present invention relates to an oxidation catalyst mat.

Structures of conventional examples and their problems In general, with regard to the activity of oxidation catalysts that completely oxidize hydrocarbons into carbon dioxide gas and water in the presence of air, those supporting platinum group metals such as platinum and palladium are said to have the highest activity. It's here. However, platinum group metals are expensive and have problems in heat resistance. On the other hand, it has recently been reported that some composite metal oxides having a bepskite structure have an activity comparable to that of platinum group metals. Composite metal oxides with a perovskite structure have high heat resistance and are relatively inexpensive in terms of cost, but there are problems in the manufacturing method. Powders with a cyperopskite structure have been prepared, but there is a problem in that the surface area, which is a basic factor for activity, is less than 1 mm''/y/y.

OBJECTS OF THE INVENTION An object of the present invention is to provide a highly active oxidation catalyst comprising a composite metal oxide having a perovskite structure with a high surface area.

Structure of the Invention In preparing an oxidation catalyst to achieve this object,
A method was used in which a predetermined ratio of various mixed salt solutions was supported on activated carbon, followed by drying and firing. According to this method, compared to the conventional powder method, a highly active oxidation catalyst with a much larger surface area per unit weight can be obtained.

Description of examples Next, examples of the present invention will be described.

Activated carbon prepared by bathing a mixed salt aqueous solution prepared by dissolving 63 parts by weight of lanthanum acetate, 7 parts by weight of cesium acetate, and 50 parts by weight of cobal acetate in an appropriate amount of water in a 10% nitric acid solution for 2 hours, washing with water, and drying. Add and leave for day and night. After drying this in a hot water bath, it was calcined at 300° C. for 1 hour, at EOOC for 1 hour, and then at 850° C. for 5 hours to obtain an oxidation catalyst for catalytic combustion.

The following Table 1 shows the reaction temperatures to obtain the respective conversion rates of the reaction gas with methane and 1% air balance. Catalyst A
Catalyst B was prepared according to the present invention and Catalyst B was prepared by the conventional powder method without the addition of activated carbon.

S, V, 18000b71 Effects of the Invention As can be seen from the above-mentioned Cloth 1, as a result of impregnating activated carbon with a predetermined amount of mixed salt aqueous solution when preparing an oxidation catalyst for catalytic combustion made of a composite metal oxide having a perovskite structure, it is possible to Pores can be utilized, reducing the particle size of the oxidation catalyst and increasing the surface area. Therefore, a highly active oxidation catalyst for catalytic combustion can be obtained.

Claims (1)

[Claims] Crystal structure A, -xA'xB1-. Of B'yO3, A
, A' consists of one or more elements selected from rare earth elements such as lanthanum and cerium, or alkaline earth metals such as strontium and calcium, with an ionic radius of 0.908 or more. X is 0-1
．． It has a numerical value in the range of 0. B, B/ is cobalt,
1 selected from transition metal elements such as iron, nickel, manganese, etc. with an ionic radius of 0.61 or more.
When preparing an oxidation catalyst for veneer combustion consisting of a composite metal oxide with a perovskite structure consisting of a species or two or more elements, and y having a value in the range of 0 to 1.0,
Production of an oxidation catalyst for catalytic combustion, characterized in that a mixed solution consisting of one type of common salt among various salts such as nitrates and phosphates in a predetermined ratio is supported on activated carbon, and then dried and calcined. Method.