Biomass to liquids via fast pyrolysis and upgrading the products: a review on chemical reaction engineering aspects

The utilization of biomass resources for producing valuable chemicals and drop-in fuels via biomass to liquid (BTL) processes has attracted much interest as alternative to today’s petroleum economy. However, biomass-derived liquids by thermochemical processes are not suitable for fuel application using available infrastructures. The undesirable characteristics of pyrolysis bio-oils originate from their high oxygen levels that should be eliminated or reduced. Among different upgrading strategies, thermocatalytic approach is considered as a promising processing for converting bio-oils into renewable carbon-neutral fuels. This includes reactions such as catalytic cracking, hydrodeoxygenation, and steam reforming similar to the mature technologies that are being used in refining and petrochemical industries. However, the high levels of oxygen containing compounds in bio-oil compared to crude oil and rapid catalyst deactivation avoid direct use of commercial catalysts and processes. Nevertheless, potential use of bio-oil as a co-feed in refineries has received attention for economic reasons. Due to the complex nature of real bio-oil, most of catalyst screening research was performed with model compounds. This article reviews the principles and current status of research and development on conversion of bio-oil to added-values chemicals and fuels.