Catalytic upgrading of intermediate pyrolysis bio-oil to hydrocarbon-rich liquid biofuel via a novel two-stage solvent-assisted process

Abstract

A novel two-stage solvent-assisted batch catalytic hydroprocessing method has been developed for upgrading intermediate pyrolysis bio-oil to produce blended liquid fuels with ≈23 wt% hydrocarbon-rich biofuel content. Stage I reactions (160 °C for 3 h, then 300 °C for 3 h) involving mixtures of dodecane and bio-oil (mass ratio = 3:2), hydrogen gas and 5 wt%-metal supported catalysts (Pd/C, Pt/Al2O3 Pd/Al2O3, Ru/Al2O3) suppressed char formation. Up to 80 wt% liquid organic products were obtained, with the biofuel component dominated by ketones and phenols. Significant amounts of water and gas (mainly CO2) were also produced. Stage II reactions (300 °C for 3 h; 5 wt% Pt/Al2O3; hydrogen gas) with Stage I organic liquid products gave >90 wt% of blended liquid fuel. Overall, up to 96 wt% bio-oil deoxygenation and 53.4 wt% bio-carbon retention were achieved in the final organic liquid product via a combination of various reaction mechanisms. Pt/Al2O3 catalyst deactivated via hydrolysis of alumina and coking in stage I but remained stable during Stage II.