Biomass pyrolysis-gasification over Zr promoted CaO-HZSM-5 catalysts for hydrogen and bio-oil co-production with CO2 capture

In order to enhance biomass conversion technology, a three-stage conversion process for biomass pyrolysis-gasification with applied Zr modified CaO-HZSM-5 catalysts is proposed for hydrogen and bio-oil co-production with CO2 capture. The process is divided into three parts: biomass pyrolysis, steam biochar gasification, and catalyst regeneration with CO2 capture. The Zr modified CaO-HZSM-5 catalysts are prepared using ion exchange and incipient wetness impregnation methods. The bifunctional catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), energy dispersive X-ray fluorescence (EDXRF), and transmission electron microscopy (TEM). The cycled CaO-Zr-ZSM-5 catalysts were also characterized by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Results indicate that CaO-HZSM-5 catalyst shows the best bio-oil selectivity (56% of phenols and 73% of aromatic compounds determined by GC/MS). Furthermore, higher hydrogen yields and concentration can be obtained using the modified CaO-Zr/H-ZSM-5 catalysts.