Upgrading of Bio-Oil Aqueous Fraction by Dual-Stage Hydrotreating–Cocracking with Methanol

Upgrading of the bio-oil aqueous fraction (BAF) for liquid hydrocarbon production was studied in this work. Hydrotreating pretreatment and methanol cocracking were combined as a dual-stage hydrotreating–cocracking process to overcome the severe coking problem caused by the hydrogen-lacking property of BAF. The influences of hydrotreating temperature, reaction pressure, and BAF/methanol ratio in feedstock were investigated. It was found that the hydrogenation efficiencies of phenols in BAF were elevated with increases in hydrotreating temperature and reaction pressure, which were important for maintaining cracking catalyst activity. However, a too high hydrotreating temperature significantly enhanced the gasification reaction and led to reduction in the final liquid hydrocarbon yield. Meanwhile, an excessively high BAF/methanol ratio obviously accelerated the deactivation of the cracking catalyst. The comparison of different cracking processes showed that dual-stage hydrotreating–cocracking was the most su...