HEAT RESISTANT TRANSITION ALUMINA AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To obtain heat resistant transition alumina especially fit for a catalyst carrier by coating the surfaces of specified transition alumina particles with an Al compd. so as to form transition alumina having a double structure. SOLUTION: The surfaces of transition alumina particles having <=0.10wt.% Na2 O content, >=90m<2> /g initial BET specific surface area and >=0.5cc/g pore volume of pores each having 32-1,000Åpore radius are coated with alumina shells contg. partially fused adjacent particles and having through holes from the outer surfaces to the alumina particles to obtain the objective heat resistant transition alumina having 1-50μm average particle diameter. The alumina shells are formed by coating the transition alumina particles as cores with 3-30 pts.wt. (expressed in terms of alumina) Al compd. based on 100 pts.wt. of the particles and firing the Al compd. at a temp. below theα-transition temp. of the transition alumina.