Tuning the selectivity of cerium oxide for ethanol dehydration to ethylene

Abstract

Ethylene is a prized raw material in the chemical industry, as well as a valued monomer to produce important commodities. At present, ethylene is mainly produced via the cracking of hydrocarbons, but there is an increasing interest in exploiting renewable biomass-derived feedstocks. The catalytic dehydration of bioethanol is a sustainable alternative route to produce ethylene. Ceria-based catalysts are active for ethanol dehydration to ethylene at low-temperature, but their selectivity is limited by the undesired formation of acetaldehyde. Partially reduced ceria can promote the dehydration of primary alcohols into alkenes over their dehydrogenation to aldehydes. This work provides computational insight into the role of surface oxygen vacancies in the selectivity of ceria. Based on this, it is proposed that the selectivity of ceria toward ethylene can be tuned by substituting Ce4+ with La3+ cations. This is tested using both density functional theory (DFT) calculations and temperature-programmed desorption (TPD) experiments to quantify the impact of doping ceria with lanthanum on the production of ethylene and acetaldehyde. The La-doped ceria sample is found to be more active and selective. This insight can guide the rational design of new ceria-based catalysts for an ethanol dehydration reaction with high selectivity to ethylene.