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

High yield of H2 of high purity from acetic acid, a model compound of bio-oil from the biomass fast pyrolysis, 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 in situ for the endothermic sorbent regeneration, in order to increase the energy efficiency of the process. A new multifunctional 1%Pd/20%Ni20%Co catalyst was developed for use both as oxygen carrier in the CL and as reforming catalyst in the SESR, while 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 which 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. H2 yield above 90% and H2 purity above 99.2 vol.% were obtained.