An INS investigation on the effect of a regeneration cycle for post-reaction Fe-modified ZSM5 catalysts applied to xylene isomerization reactions (TOSCA)

The global demand for p-xylene production is considerable. One production route involves the use of ZSM5 zeolites to affect the isomerisation of m-xylene to p-xylene. However, catalyst deactivation constitutes a significant impediment to the process operation. In partnership with a major catalyst manufacturer, this application seeks to use the TOSCA spectrometer to examine the effect of a regeneration cycle on a series of new Fe-doped ZSM5 catalyst formulations under development. Carbon deposition as a function of time-on-stream results in a significant reduction of activity, necessitating the zeolite to experience an oxidative treatment to burn off the ‘coke’. Laboratory testing has established that discrete Fe loadings can induce ‘soft’ coke formation (reversible via regeneration) over ‘hard’ coke (irreversible). However, the durability of the Fe-doped catalysts with respect to the regeneration treatment is uncertain. TOSCA beamtime is requested to analyse a selection of post-reaction samples after deployment of a regeneration stage. This procedure will provide spectral insight as to how the regeneration stage perturbs the catalysts’ acid site distribution, with particular emphasis on strong Brønsted acid sites. Further measurement of the samples after a second reaction sequence will be used to speciate the form of the hydrocarbonaceous species that results post-regeneration. This TOSCA application is linked to an associated MAPS proposal.