FINE PARTICLES OF GAMMA-ALUMINA-MAGNESIA MULTIPLE OXIDE AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To industrially produce fine particles ofγ-alumina-magnesia multiple oxide exhibiting heat resistance and durability, less liable to a change in the crystal form, specific surface area and particle diameter even at high temp. and capable of maintaining catalyst carrier function and catalytic activity over a long period of time. SOLUTION: A starting material contg. Al and Mg is evaporated with thermal plasma in an oxygen atmosphere. Preferably an arc discharge is caused between an electrode comprising an Al-Mg alloy or based on the alloy and a counter electrode in a state that protects the latter electrode with an inert gaseous stream and allows the stream to orient toward the former electrode to generate a plasma flame. The Al-Mg alloy is evaporated with the plasma flame and an oxygen-contg. gas is introduced and brought into contact with a vapor stream generated in the plasma flame and/or on the downstream side of the plasma flame.