Solvent extraction, biomass economics

The ideal HMF production process would use raw biomass as its feedstock, without the necessity for extensive drying or pretreatment (apart fi om mechanical reduction to particle sizes which do not suffer mass transfer limitations). Reactions would proceed in high yield over short time scales under mild conditimis in inexpensive media and use simple, non-foulable catalysts. The HMF product would be isolated without recourse to distillation or protracted solvent extraction, and all materials would be easily recyclable. Except for product yield, none of these objectives has currently been met in such a way as to be reducible to practice on an industrial scale. In the end, it is a matter of economics. When the dust settles, only the most competitive, industrially viable processes will be left standing, and the rest will be consigned to history. 

We seek to determine an optimal composition of a multicomponent solvent utilized to remove hydrocarbons from yeast. The major index of purification here is the hydrocarbon content in biomass upon extraction (y). For technological and economic reasons, the experimental design is accomplished in a local section of the concentration, Fig. 3.23. 

Although CO2 is inhibitory to microbes, compressed hydrocarbon solvents may be appropriate for extractive bioconversions and extractions in biphasic (aqueous-compressed solvent) systems. Our laboratory investigated the metabolic activity of the anaerobic, thermophilic bacteria Clostridium ther-mocellum as a model system (45). Thermophilic bacteria have a distinct advantage over conventional yeasts for ethanol production in their ability to use a variety of inexpensive biomass feedstocks. Extractive fermentation using compressed solvents is an approach to address the end-product toxicity of these bacteria to ethanol and improve the economic viability of biofuel production by thermophilic organisms. 

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