(633d) Production of Fermentation Substrates from Thermal Deconstruction of Lignocellulose

Authors: 
Rover, M., Iowa State University
Hall, P. H., Iowa State University
Smith, R. G., Iowa State University
Brown, R. C., Iowa State University
Stanford, J. P., Kansas State University
Fast pyrolysis of biomass utilizing a condensation train that condenses and collects pyrolysis products according to their vapor pressures has permitted the separation and purification of multiple bio-oil streams. Heavy ends bio-oil derived during fast pyrolysis of lignocellulosic and carbohydrate fractions of biomass can be separated by liquid-liquid extraction with water for the effective recovery of sugars (water-soluble) and phenolic oil (water-insoluble). While the light ends bio-oil contains the vast majority of water, we have the ability to separate the water from the organics. Our research has shown that the separate recovery of these streams and removal of toxic inhibitors allows for effective fermentation substrates. These substrates are obtained from both heavy and light ends. The sugar stream recovered from the heavy ends can be cleaned using polymeric resin absorbents, SP207 or XAD-4. These resins adsorb the phenolics remaining in the water-soluble sugar stream, ultimately producing a clean stream of sugars. This stream can be hydrolyzed and used in fermentation to butanol or ethanol or directly fermented with ethanol-producing Escherichia coli. The water-insoluble fraction from the heavy ends can be further separated into monomeric phenols and larger molecular weight phenols with liquid-liquid extraction utilizing toluene as the solvent. Exploitation of nontoxic emulsifiers has permitted utilizing the monomeric phenol fraction, obtained using toluene, for potential biochemical transformation, by Pseudomonas putida KT2440, to muconic acid. Light ends contain carboxylic acids, water and other light oxygenates. The carboxylic acids produced during pyrolysis can be separated from the water stream using ionic resin or membrane technology, both hydrophobic and hydrophilic, producing a clean stream of water that can be easily be disposed of. The acetic acid, by far the highest concentration of carboxylic acids in light ends, is then used in fermentation to methane for process heat.