Reaction kinetic approach to study activity, selectivity and deactivation of Pt/Al 2O 3 in n-hexane conversion

Abstract

In this work factors influencing the activity and selectivity of the Pt/Al 2O 3 catalyst were investigated in n-hexane conversion. Based on steady state and transient reaction kinetic data it was concluded that the main factors controlling the selectivity of this catalyst in n-hexane conversion are: (i) the amount of substrate (n-hexane) chemisorbed, i.e. the substrate coverage and (ii) the mobility of all surface species including chemisorbed hydrogen. These two factors strongly influence both the extent of dehydrogenation and the geometry of the surface species originated from the hydrocarbon. It is suggested that on the Pt sites there are at least two types of surface intermediates involved in the formation of different reaction products. Surface carbon, responsible for the catalyst deactivation, appeared to be a selective poison, which strongly suppressed the formation of benzene.