Hydrogen rich fuel gas production by gasification of wet biomass using a CO_2 sorbent

摘要

Hydrogen rich fuel gas production by gasification of wet biomass accompanied by CO_2 absorption is proposed. The paper addressed this topic, and experiments were conducted to investigate the effects of the moisture content (M), the molar ratio of Ca(OH)_2 to carbon in the biomass ([Ca]/[C]) and the reactor temperature (T) on hydrogen production and CO_2 absorption by CaO. Measurement of the calcium compounds in solid residues was carried out with XRD and SEM. The results show that directly gasifying of wet biomass not only favors hydrogen production but also promotes CO_2 absorption by CaO. For the experiment with wet biomass (M = 0.90), the H_2 yield is increased by 51.5% while the CO_2 content is decreased by 28.4% than that for experiments with dry biomass (M = 0.09). CaO plays the dual role of catalyst and sorbent. It is noteworthy that CaO reveals a stronger effect on the water gas shift reaction than on the steam reforming of methane. The increase of the reactor temperature contributes to produce more H_2, but goes against CO_2 absorption by CaO. XRD spectrum and SEM image of the solid residues further confirmed that high temperature is unfavorable to CO_2 absorption by CaO. For the new method, the optimal operating temperature is in the 923-973 K range.