Mechanism Study Of Coupling Reaction Of N-hexane And Methanol Over Zeolite Catalyst

The effective coupling of exothermic methanol conversion with endothermic hydrocarbon cracking will undoubtedly lead to a practical application since its energetic and economic advantages. However, its mechanism process is unknown up to now and a detailed investigation is needed to understand and develop this promising catalytic process. In this thesis, with n-hexane cracking as model reaction, the methanol coupled conversion of alkanes on zeolite catalysts have been studied intensively with a pulse-reaction system as well as the technique of TPSR and FTIR. Furthermore, the observed kinetic behavior was also analyzed in order to verify the proposed mechanism model of this coupling reaction.The pulse catalytic tests have shown that methanol could greatly improve alkane activation, especially for the alkane with strong adsorption capacity over zeolite surface. Moreover, the results indicated that the improvement role could be strengthened on the zeolite with highly Br?nsted acid sites density, larger pore structure, and lower reaction temperature. These results clearly suggested that with methanol introduction, initial activation of n-hexane and following chain propagation may more possibly occur in bimolecular way.The FTIR and TPSR analysis accompaning catalytic tests further demonstrated that methanol adsorption on acid sites prior to n-hexane and immediately adsorped methanol was transformed to surface methoxy groups and worked as the active sites for n-hexane conversion. It improved the initial activation of n-hexane by a hydride transfer way. The acceleration of methanol...