The shape selectivity in the skeletal isomerisation of n-butene to isobutene

This study explores several microporous materials to identify the most suitable structures for a skeletal isomerisation of n-butene to isobutene. The 8-membered ring zeolites are not suitable for skeletal isomerisation of n-butene to isobutene because their pore diameter does not allow diffusion of isobutene. The 12-membered ring zeolites do not suppress the formation of carbonaceous deposits and their pores are quickly blocked. The most suitable materials are the catalysts with a pore diameter between 4 and 5.5 Angstrom. This is the range as met in the 10-membered ring molecular sieves. These materials allow an isobutene diffusion but they suppress the formation of dimers (and oligomers) which are intermediates leading to by-products. (C) 1997 Academic Press.