ACTIVE SITES OF ALUMINUM PHOSPHATE CATALYSTS FOR THE ISOMERIZATION OF cis-2-BUTENE

Various aluminum phosphate-alumina mixed catalysts (APA) having different P/Al ratios were prepared, and their activity and selectivity for n-butene isomerization as well as their physical properties were examined. The APA catalysts consisted of crystalline aluminum phosphate and alumina. Some APA catalysts showed infinite selectivity (initial trans-2-butene/1-butene ratio) in cis-2-butene isomerization; this extraordinary selectivity indicates that the surfaces of the catalysts are occupied by aluminum phosphate featuring such selectivity. Others, however, showed no infinite selectivity, which suggests that alumina involved in them catalyzes the cis-2-butene isomerization too. It was also concluded that the active sites featuring the infinite selectivity were located in amorphous aluminum phosphate moiety in the neighborhood of catalytically inactive crystalline aluminum phosphate.