Vapor-phase deoxydehydration of 1,2-propanediol to form propylene over Cu-loaded H3PO4/SiO2-Al2O3 catalyst

Abstract

Vapor-phase catalytic deoxydehydration of 1,2-propanediol (1,2-PDO) to form propylene was performed over various metal-loaded catalysts in an H2 flow at an ambient pressure. Cu-based catalysts exhibited a relatively high activity for the formation of propylene, while other metal-based catalysts, such as Pt-, Ru-, Rh-, Ni-, and Co-loaded SiO2-Al2O3, primarily produced C-C bond cleavage products. Cu-loaded H3PO4/SiO2-Al2O3 catalysts showed the best catalytic performance, and the catalyst with a Cu and H3PO4 loading of 8 and 10 wt%, respectively, could provide a propylene selectivity of 95.0% with a complete conversion of 1,2-PDO at 280 °C. The Cu-loaded H3PO4/SiO2-Al2O3 catalysts primarily contained Lewis acid sites, and the Cu particles were well dispersed on the catalyst surface with an averaged particle size of 3.1 nm. It is proposed that the vapor-phase deoxydehydration of 1,2-PDO to propylene undergoes multi-step reactions with propanal and 1-propanol as the reaction intermediates.