The catalytic isomerization of 2, 4-diphenyl-1-butene over two kinds of silica-alumina catalysts (IS and Neobead-P) was carried out at 300°C in the range of 0.1×10⁴-40×10⁴g-catalyst •sec/g-mol-feed using a fixed bed flow reactor system.
The main products formed over the two catalysts were different; 1-methyl-1-phenylindan and 1, 3-diphenyl-2-butenes were the main products over the IS catalyst while 1, 3-diphenyl-2-butenes were the main products over the Neobead-P catalyst. It was found that these products were formed by catalytic isomerization reactions of 2, 4-diphenyl-1-butene (D.P.B.E). One of the reactions was isomerization of D.P.B.E to 1-methyl-1-phenylindan which occurred only over the IS catalyst, and the other was double-bond isomerization of D.P.B.E which occurred over both the IS and Neobead-P catalysts.
The experimental results were interpreted to be attributable to the differences in the acidic properties of the catalysts. In particular, it was found that strong acid sites of H₀<+1.5 promoted the formation of 1-methyl-1-phenylindan.