Bioethanol conversion into hydrocarbons on HZSM-5 and HMCM-22 zeolites: Use of in situ DRIFTS to elucidate the role of the acidity and of the pore structure over the coke formation and product distribution

Abstract

In the last years there has been an increasing interest for the use of ethanol not only as biofuel but also as raw material for the production of petrochemicals. In the present work the conversion of ethanol into hydrocarbons was investigated over zeolites with different acidic properties and porous structure (HZSM-5 and HMCM-22). The samples used were active for ethanol conversion and both their acidic properties and porous structure played an important role on product selectivity. HZSM-5 zeolite was the most promising catalyst for propene formation. Raman spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were also employed to investigate the carbon species deposited on the zeolites and the adsorbed species formed during the reaction, respectively. DRIFTS results show that coke formation was severely inhibited by the pore structure of HZSM-5 justifying the high stability of this zeolite.