The Effect of in Situ Phenol Hydrogenation with Raney Ni on the Fate of Hydrogen from Glycerol Aqueous Phase Reforming

The fate of hydrogen during glycerol aqueous phase reforming (APR) and the effect of in situ phenol hydrogenation (IGAPH) with Raney Ni on the glycerol APR mechanism were studied. Glycerol APR proceeds through parallel routes via 1,2-propylene glycol or ethylene glycol. Combining phenol hydrogenation with glycerol APR changes the distribution of hydrogen among products. Hydrogen for hydrogenolysis of glycerol APR intermediate products was diverted to phenol hydrogenation, leading to enhanced glycerol conversion and suppressed hydrogenolysis. This hydrogen transfer occurred on the catalyst surface without formation of hydrogen gas as indicated by empirical results from open/closed system reactors. The lean hydrogen environment induced by hydrogen scavenging phenol on Raney Ni promoted the ethylene glycol route generating additional hydrogen for phenol hydrogenation. Moreover, removal of CO2 by adjusting process pressure in the open system can enhance phenol conversion during IGAPH and eliminate the burden of operating at autogenous high pressure. In addition to producing renewable hydrogen from glycerol and water, in situ APR-hydrogenation eliminates the transport barrier of gaseous hydrogen diffusion into solution.