Insights into the Reaction Mechanism of Ethanol Conversion into Hydrocarbons on H-ZSM-5

Ethanol dehydration to ethene is mechanistically decoupled from the production of higher hydrocarbons due to complete surface coverage by adsorbed ethanol and diethyl ether (DEE). The production of C3+ hydrocarbons was found to be unaffected by water present in the reaction mixture. Three routes for the production of C3+ hydrocarbons are identified: the dimerization of ethene to butene and two routes involving two different types of surface species categorized as aliphatic and aromatic. Evidence for the different types of species involved in the production of higher hydrocarbons is obtained via isotopic labeling, continuous flow and transient experiments complemented by UV/Vis characterization of the catalyst and ab initio microkinetic modeling.