Influence of the Activation Conditions on the Catalytic Behaviour of Offretite

The conversion of cyclohexane has been used as test reaction to study the behaviour of mine catalysts prepared from four parent offretites. Large differences in activity, selectivity and stability were evidenced, which could not be related to the bulk properties (composition and porosity) of the zeolites. The results suggest that only a fraction of the intrazeolitic surface is involved in catalysis due to the matching of sizes between the reactant and the pores and that deactivation results from the accumulation of coke in zones of high protonic density generated by an heterogeneous exchange of the crystals.