One-pot hydrogenolysis of cellulose to bioethanol over Pd-Cu-WOx/SiO2 catalysts

The chemo-catalytic production of ethanol from nonedible lignocellulosic biomass is essential for mitigating energy shortage. In this work, we developed a multifunctional Pd-Cu-WO x /SiO 2 catalyst for the one-pot aqueous-phase conversion of cornstalk-derived cellulose to ethanol with a yield of 42.5C% at 300 °C and 4 MPa H 2 . Kinetic studies demonstrated that the transformation of cellulose to ethanol followed a number of consecutive steps namely, cellulose hydrolysis to glucose with H + in hot water (k 1 ), glucose conversion to glycolaldehyde over W species (k 2 ), glycolaldehyde hydrogenation to ethylene glycerol (EG) over Pd (k 3 ), and EG hydrogenolysis to ethanol over Cu (k 4 , rate-determining step). The individual rates were well balanced on Pd, Cu, and WO x species to achieve an ethanol formation rate of 0.163 g·g Cat . −1 h −1 . The addition of Au to Cu-WO x species led to a relatively low k 3 and thus the formation of a substantial amount of humins, while the Ru introduction catalyzed the over-hydrogenolysis of ethanol to methane and ethane with a high rate, thereby lowering the selectivity to ethanol. The characterization results showed that both the electronic properties of Cu + species and the Cu + /Cu 0 ratio on the Pd-Cu-WO x /SiO 2 catalyst contributed to a specific C O bond cleavage, especially for EG hydrogenolysis to ethanol during the cellulose conversion.