Study on the process of transformation of olefin into aromatics over HZSM-5

In order to investigate the process of transformation of olefin into aromatics over HZSM-5, TPSR and pulse reaction were performed over HZSM-5, using alkenes, dienes and cycloolefins as reactants. The results illustrated that the initial step (i.e. the formation of diene or cycloolefin) in all hydrogen-transfer reactions during alkene aromatization could be carried out at temperatures lower than 200 degrees C, while the further hydrogen-transfer reactions between dienes/cycloolefins and alkenes/cycloolefins, leading to the formation of aromatics required relatively higher temperatures. It is concluded that the formation of aromatics is a result of repeated adsorption-reaction-desorption of alkenes on various acid sites. Furthermore, the pathway of olefin aromatization was not by a single pathway. (c) 2005 Elsevier B.V. All rights reserved.