Comparison of Various Ion Exchange Resins for the Separation of Phenols in a Wood Pyrolysis-Based Biorefinery

Fast pyrolysis of pre-treated birch wood in a super-heated steam environment produces a condensate rich in anhydrosugars. With the objective to obtain several product streams from this condensate, the possibility of extracting additional chemical species is explored, thus promoting the development of a pyrolysis-based biorefin-ery. In this work, the extraction and recovery of pyrolytic phenols from birch wood pyrolysis condensate was stu-died using ion exchange resins. With an aim to achieve effective phenol recovery, while obtaining high purity levoglucosan, basic ion exchange resins, both in OH⁻ and Cl⁻ form, as well as polystyrene-divinyl resins without functional groups were compared. This study characterizes the influence of sorbent matrix type and porosity, functional group and counter ion on the sorption of various aromatic compounds. It was concluded that the counter ion of the ion exchange resins had the most influence on the pyrolytic phenol adsorption, while in the case of unfunctionalized resins smaller pore size improved removal of phenols from the pyrolysis liquids. Of the resins tested, the most effective at the removal and recovery of pyrolytic phenols were strongly basic, macroporous, anion exchange resins in OH⁻ form. The possibility to reuse the sorbents and solvents is explored to make the over-all process more environmentally friendly and economically feasible.