Hydrogen-rich syngas production via sorption-enhanced steam gasification of biomass using FexNiyCaO bi-functional materials

Sorption-enhanced steam gasification (SESG) of biomass using Ca-based materials is a promising technology for H2 production and in-situ CO2 capture. Herein, FexNiyCaO bi-functional materials were prepared from carbide slag and used for hydrogen-rich syngas production in a two-stage fixed-bed system with continuous biomass feeding. The results showed that the Fe-doped CaO exhibited better catalytic activity on the water gas shift reaction than Ni-doped CaO, while the Ni-doped CaO was more favorable to steam reforming of tar than Fe-doped CaO. Besides, bimetallic Fe7Ni3CaO possessed the best performance in cyclic CO2 capture capacity, H2 production and catalytic stability among all monometallic and other bimetallic Fe/Ni-doped CaO bi-functional materials. The positive interaction between Fe and Ni alleviated the sintering of Ca2Fe2O5 and improved the resistance of NiO to carbon deposition, thereby improving the catalytic activity and stability of Fe7Ni3CaO. When the catalyst/biomass mass ratio was 3.33, the H2 concentration and H2 yield for Fe7Ni3CaO were 69.2 vol% and 660 mL/g, respectively. Finally, Fe7Ni3CaO exhibited good cyclic stability in H2 production, and the H2 yield of Fe7Ni3CaO was still more than twice that of pure CaO after 5 SESG cycles.