Utilization of CO2 and biomass char derived from pyrolysis of Dunaliella salina: The effects of steam and catalyst on CO and H2 gas production

Biomass char, by-product of Dunaliella salina pyrolysis at a final pyrolysis temperature of 500 °C, was used as feedstock material in this study. The reactions of biomass char with CO2 were performed in a fixed-bed reactor to evaluate the effect of temperature and steam on the CO2 conversion, CO yield and gas composition. The CO2 conversion and CO yield without steam and catalyst reached about 61.84% and 0.99 mol/(mol CO2) at 800 °C, respectively. Steam and high temperature led to high CO2 conversion. A new approach for improving H2 was carried out by using biomass char and Au/Al2O3 catalyst, which combined steam gasification of biomass char and water gas shift reaction, and the H2 concentration was 1.8 times higher than without catalyst. The process not only mitigated CO2 emission and made use of residual biomass char, but also created renewable source.