Skeletal isomerization of 1-butene over micro/mesoporous materials based on FER zeolite Original Research Article

Skeletal isomerization of 1-butene has been studied over composite micro/mesoporous zeolitic catalysts prepared by the recrystallization of ferrierite (FER) in alkaline solutions in the presence of cethyltrimethylammonium bromide and by the desilication of FER in alkaline solutions. Desilication procedure led to the creation of large mesopores in zeolite crystal with broad distribution of size. Recrystallization procedure resulted in two types of mesoporosity: uniform intracrystalline mesopores homogeneously distributed along the crystal and intercrystalline ordered mesoporous layers covering zeolite crystal. Recrystallized materials showed improved catalytic performance in skeletal isomerization of 1-butene with respect to both parent and desilicated ferrierites. The effect is due to the improved accessibility of the acid sites and the creation of new pore mouths, in which the active carbonaceous species responsible for selective pseudo-monomolecular pathway can be formed. The improved stability of catalytic activity with time on stream is due to coating of ferrierite crystals with mesoporous layes, which prevent the deactivation of the catalysts. The best catalytic performance was achieved over composite micro/mesoporous materials with intermediate degree of recrystallyzation due to proper balance between zeolitic and mesoporous phases and the amount and density of the acid sites.