Propene oligomerization on Beta zeolites: Development of a microkinetic model and experimental validation

Abstract

The microkinetic modelling methodology that we developed previously to describe Brønsted acid-catalyzed propene oligomerization on medium-pore MFI zeolites has been extended successfully to large-pore Beta zeolites. The extension of the model was supported by the identification of the key descriptors that account for the different topologies and acid strengths of the zeolite frameworks (physisorption enthalpies, stabilization enthalpies, frequency factors). The model is validated with experimental conversion and selectivity data measured in a plug-flow reactor on a commercial Beta zeolite over a range of operating conditions. Analysis of net reaction rates allowed identifying the preferred pathways that increase oligomerization selectivity toward C9 species with increasing propene pressure. The model was additionally used to investigate how the stabilization enthalpies of chemisorbed intermediates, an important catalyst descriptor, influenced the selectivity and surface coverage at iso-conversion. This analysis provides mechanistic insights into the propene oligomerization reaction network and its dependence on zeolite topology, and demonstrates how microkinetic models can describe catalyst behaviour and aid in catalyst and process optimization.