S117: Developing a hybrid conversion process for producing fuels and chemicals from lignocellulosic biomass

Producing biofuel and chemicals from lignocellulosic biomass has attracted significant research efforts. Currently, the majority of those efforts are focusing on biological platform, in which biomass is converted into reduced sugars through pretreatments and enzymatic hydrolysis, followed by fermentation of the sugars. Researchers at Iowa State University have been working on a novel hybrid platform as an alternative to the biological platform. I.e., a thermochemical based fast pyrolysis is used to convert biomass into pyrolytic substrates, then, a biological process is used to ferment those substrates into fuel and chemicals. Compared with biological platform, the hybrid platform is potentially faster, cheaper, and applicable to a wide spectrum of feedstocks.

To better utilize the pyrolytic substrates, the crude pyrolytic subtract solution was fractionated into five distinct stage fractions (SF) with distinctive physical and chemical characteristics, and each fraction can be used for different purposes. The stage fraction #1 (SF1), which contains the majority of levoglucosan, was used as a fermentation substrate for E-coli fermentation producing ethanol, while stage fraction #5 (SF5), which contains the majority of acetic acid and acetol, was used for heterotrophic microalgal and yeast fermentation cultivation for lipid and 1,-2 propanedial production, respectively. Currently research focus on mitigating the toxicity of those bio-oil streams though various treatment methods such as activated carbon and alkali treatment, and enhancing the toxicity tolerance of the microorganisms through metabolic evolution.  Eventually, the hybrid process will be providing a novel and viable platform for making fuels and various chemicals.