Blends of bio-oil/biogas model compounds for high-purity H2 production by sorption enhanced steam reforming (SESR): Experimental study and energy analysis
S. Rodríguez, A. Capa, R. García, D. Chen, F. Rubiera, C. Pevida, M.V. Gil
Abstract
H2 production by sorption enhanced steam reforming (SESR) of bio-oil/biogas blends was demonstrated in a fluidized bed reactor. It combines steam reforming (SR) with simultaneous CO2 capture by a solid sorbent. SESR was performed on a Pd/Ni-Co catalyst derived from a hydrotalcite-like material (HT) using dolomite as CO2 sorbent. Bio-oil from fast pyrolysis of biomass is a carbon–neutral and renewable energy source with great potential for clean H2 production by steam reforming processes. Biogas is also a promising renewable bio-based resource for hydrogen generation that can be used to increase the H2 production of a biomass-based plant. In turn, it could improve the energy efficiency of the process due to the exothermic reaction of the CO2 contained in biogas with the sorbent. Bio-oil composed of acetic acid and acetone (1/1 mol/mol) and biogas composed of CH4 and CO2 (60/40 vol%) were used as fuels. They were blended (50 wt% bio-oil + 50 wt% CH4) to study the SESR process. Effects of temperature, steam/C molar ratio, and pressure on the process performance were evaluated. SESR results showed an effective reforming of bio-oil/biogas blends and an enhancement in the H2 production and fuel conversion compared to conventional SR. Higher temperature and steam/C ratio, but lower pressure, favored H2 yield and purity. High H2 yield (87.1%) and H2 purity (98.6 vol%) were obtained at 625 °C and 2.5 bar (steam/C molar ratio three times higher than the stoichiometric value). The thermodynamic energy analysis of the SESR of bio-oil/biogas blends rendered 1.34% higher cold gas efficiency (CGE) than bio-oil SESR.