(576c) Supercritical Fluid Processing of Biomass-Derived Pyrolysis Oil

Authors: 
Amundsen, T. J., Mainstream Engineering Corporation
Hagelin-Weaver, H., University of Florida
Liquid hydrocarbon fuels are essential to our current modes of transportation due to their high energy density. However, new technologies are needed to satisfy the demand for these fuels using sustainable resources. Biofuels are an attractive renewable substitute for petroleum-based fuels. The challenge is that woody biomass, although abundant enough to supply a meaningful fraction of the nationâ??s fuel, is recalcitrant to many chemical processes. Fast pyrolysis to convert biomass into a crude bio-oil has gained recent attention as the basis of a distributed biofuels production capability. Despite promise, the disadvantages of fast pyrolysis are that the resulting bio-oil has low energy density, high water content, acidic pH, and poor storage stability. Vigorous research efforts have been mounted in the past few years to upgrade and stabilize pyrolysis bio-oil. Unfortunately, bio-oil upgrading has been plagued by unacceptable hydrogen consumption, catalyst failure, and inability to process whole bio-oil.

A particularly attractive scenario is to efficiently separate out multiple fractions of bio-oil so that each portion can be treated with a process specifically tailored to the functionalities present in that phase. Bio-oil can be selectively condensed to create multiple fractions, or separated during post-processing. Efficient extractive post-processing is an appealing approach due to the potential for tailoring an extraction for specific components, and facilitating in-situ upgrading where hydrotreating/cracking can be performed during the extraction. Supercritical fluid processing is especially promising for this application due to the ease of solvent recovery, good solvency for organic chemicals and the flexibility of tailoring the solvent for desired chemical fractions. Results of supercritical fluid processing of biomass-derived pyrolysis oil will be presented. This includes characterization of the fractions obtained during various processing conditions as well as conversion strategies tailored to these specific fractions.