Inelastic Neutron Scattering Studies of Propene and 1-Octene Oligomerisation in HZSM-5

Abstract

Neutron scattering methods (quasielastic neutron scattering (QENS) and inelastic neutron scattering (INS)) have been used to study the reactivity of propene and 1-octene over the acid zeolite catalyst H-ZSM 5. The high activity of the catalyst causes the alkenes to form linear oligomers below room temperature. INS has shown that the reaction proceeds through a hydrogen-bonded intermediate. Studies using propane as an inert analogue for propene have found that the adsorbed C3 molecules spend the majority of their time undergoing short jumps within the pore channels of the zeolite. Hydrothermal de-alumination plays an important role in determining the activity of zeolite catalysts. De-alumination was found to delay the onset of catalytic activity for oligomerization to higher temperatures and increase the mobility of hydrocarbons within the zeolite, both due to reduced acid-hydrocarbon interactions.