CHROMIUM-ALUMINUM ORTHOPHOSPHATES .1. STRUCTURE, TEXTURE, SURFACE-ACIDITY AND CATALYTIC ACTIVITY IN CYCLOHEXENE SKELETAL ISOMERIZATION AND CUMENE CONVERSION OF CRPO4-ALPO4 CATALYSTS

A series of CrPO4-AlPO4 (5-10wt.% AlPO4, CrAlP) catalysts have been pr epared by precipitation in aqueous ammonia or in aqueous ammonia-propy lene oxide. The catalysts were calcined at 773-1273 K. All catalysts w ere amorphous for calcination temperatures below 1073 K. At 1273 K the beta-CrPO4 structure was formed. CrAlP catalysts exhibited low surfac e areas which decreased as the calcination temperature increased. More over, surface acidity (acid amount and acid strength), measured by ads orption of pyridine and 2,6-dimethylpyridine at various temperatures ( 573-673 K) by using a pulse method, was better than for the individual components. This increased surface acidity is responsible for their b etter performance for cyclohexene skeletal isomerization (CSI) and cum ene conversion (CC), reactions that were selected as dynamic methods f or surface-acid characterization.