Kinetics of the Homogeneous and Heterogeneous Coupling of Furfural with Biomass-Derived Alcohols

The tandem dehydrogenation and aldol condensation of butanol with furfural was investigated over homogeneous and heterogeneous catalysts using kinetics and isotope effects. In the homogeneous system, Ni(dppe)Cl-2 catalyzes the transfer dehydrogenation of butanol to the furfural, whereas the aldol condensation of butyraldehyde and furfural takes place over the basic K2CO3 cocatalyst. In the heterogeneous system, a transition-metal-free mixed Mg-Al oxide, both the transfer hydrogenation and aldol condensation take place over the basic sites of the catalyst, and the rate-determining step is the alpha-hydride transfer from the butanol to the furfural.