A conceptual framework for an integrated lignin biorefinery-petroleum refinery

Co-feeding of renewable feedstocks in general, and lignin streams in particular, in petroleum refineries is an attractive means of increasing the proportion of renewable fuel. Four separate units in an integrated refinery can be envisioned using lignin as a feedstock: the hydrotreater, the fluidised catalytic cracker, the hydrocracker and the slurry hydrotreater. A conceptual process design study, including cost assessments, is presented on the possibility of co-feeding lignin in one of these stages in a conventional crude oil refinery. The addition of lignin to an existing diesel hydrotreating unit is investigated in a refinery environment. Rigorous process simulation models were developed for such an integrated lignin-petroleum refinery based on real data. The lignin product shows good potential of ending up in the gasoline pool with about one third having a boiling point within the gasoline range, one third in the diesel range and the final third ending up in the LPG and kerosene pools. The total production cost of gasoline from lignin is estimated to be 0.82 €/L. If all or most tax reductions on fuels from sustainable sources could be utilised, lignin would be a viable resource for the production of biomass-based gasoline.