Mechanistic Studies on the Coupled Reaction of n-Hexane and Ethanol Over HZSM-5 Zeolite Catalyst

The coupled reaction of n-hexane and ethanol over HZSM-5 zeolite has been, for the first time, investigated with a pulse-reaction system. The catalytic reaction results showed an improvement of the initial conversion activity of n-hexane when ethanol was introduced as co-reactant. The FT-IR analysis revealed that the ethanol molecules adsorbed on Bronsted acidic sites were immediately transformed into surface ethoxy groups, which were active species for converting n-hexane and improving the initial conversion activity of n-hexane by a bimolecular hydride transfer mode. Also, the catalytic tests suggested that alkenes resulting from the transformation of ethanol could not enhance the initial conversion of n-hexane compared to active ethoxy groups at the shortest contact time. A mechanism involving the ethoxy groups was proposed to understand the coupled reaction of ethanol and n-hexane.