Optimising H2 production from model biogas via combined steam reforming and CO shift reactions

H, production was studied through steam reforming of a clean model biogas in a fluidized-bed reactor followed by two stages of CO shift reactions (fixed-bed reactors). The steam reforming of biogas was per-formed over 11.5 wt.% Ni/Al2O3 and a molar CH4/CO2 ratio of 1.5 was employed as clean model biogas. Excess steam resulted in strong inhibition of carbon formation and an almost complete CH4 (>98%) conversion was achieved. To optimise H-2 production, CO shift reactions were carried out at high (523-723 K) and low temperatures (423-523 K) using commercial catalysts. based on Cu/Fe/Cr and Cu/Zn, respectively. Increasing steam concentrations led to a lean CO, high H-2 product. The final product compositions following low temperature CO shift reaction (steam to dry gas ratio of 1.5 at 483 K) yielded H-2 at 68% and a CO concentration of 0.2% (equivalent to CO conversion of > 99%). (c) 2005 Elsevier Ltd. All rights reserved.