Evaluation of Canadian tree barks to produce sustainable biocrude

Abstract

Ten bark species of Canadian-grown trees were categorized into softwoods and hardwoods and then screened for bio-crude production using hydrothermal liquefaction under identical conditions. The biocrude yield from these screenings ranged from 16 to 64 wt.%. Among the hardwoods, birch bark produced a biocrude yield of over 55 wt.% with a heating value of 35 MJ/kg. Softwood species such as fir, pine, and spruce yielded around 30 wt.% biocrude, with heating values between 32.6 and 33.9 MJ/kg. The biocrude yield was analyzed in relation to fiber content, volatile matter, and extractives to determine their impact. It was found that the biocrude yield had a strong correlation with the volatile matter in the feedstock. The screening suggests that fir, pine, and spruce barks, due to their relative abundance, have the potential for further exploration, including upgrading biocrude to meet transportation fuel specifications in Canada. Detailed physicochemical characterizations were performed on the Canadian-grown feedstocks, biocrudes, and hydrochars. Based on the characterization results, the biocrude cannot be used directly as fuel; therefore, catalytic upgrading is recommended to reduce the oxygen content for co-refining in existing refineries. Hydrochars were also characterized, and promising applications have been proposed.