Synergetic deoxygenation and demineralization of biomass by wet torrefaction pretreatment and its influence on the compound distribution of bio-oil during catalytic pyrolysis

Abstract

In this work, the synergetic deoxygenation and demineralization of biomass by wet torrefaction pretreatment (WTP) coupled with catalytic fast pyrolysis (CFP) using the metal incorporated hierarchical HZSM-5 were employed to enhance the concentration of light aromatics in bio-oil. Results showed that the removal rates of O, Na, K, Ca, and Mg increased with the raise of the WTP temperature, reaching their maximum rates of 47.96%, 81.13%, 90.99%, 66.09%, and 86.65%, respectively. In addition, the NaOH desilication pretreatment and the incorporation of metals (Zn, Ga, and Fe) on HZSM-5 could improve the pore size distribution by creating some mesopore in the framework, and thus provide more acid sites for the hydrodeoxygenation reaction. The optimal operation parameter for CFP was the wet torrefaction temperature of 220 ºC, pyrolysis temperature of 850 ºC, and the catalyst-to-feedstock ratio of 1:3 using the Zn incorporated hierarchical HZSM-5 as catalyst.