Multifunctional Pd/Ni-Co Catalyst for Hydrogen Production by Chemical Looping Coupled With Steam Reforming of Acetic Acid

High yield of high-purity H-2 from acetic acid, a model compound of bio-oil obtained from the fast pyrolysis of biomass, was produced by sorption-enhanced steam reforming (SESR). An oxygen carrier was introduced into a chemical loop (CL) coupled to the cyclical SESR process to supply heat insitu for the endothermic sorbent regeneration to increase the energy efficiency of the process. A new multifunctional 1%Pd/20%Ni-20%Co catalyst was developed for use both as oxygen carrier in the CL and as reforming catalyst in the SESR whereas a CaO-based material was used as CO2 sorbent. In the sorbent-air regeneration step, the Ni-Co atoms in the catalyst undergo strong exothermic oxidation reactions that provide heat for the CaO decarbonation. The addition of Pd to the Ni-Co catalyst makes the catalyst active throughout the whole SESR-CL cycle. Pd significantly promotes the reduction of Ni-Co oxides to metallic Ni-Co during the reforming stage, which avoids the need for a reduction step after regeneration. H-2 yield above 90% and H-2 purity above 99.2vol% were obtained.