科研之友
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摘要
Concerns over energy security, economic development and climate change are driving the search and development of bio-fuels as one of a number of possible alternatives to fossil fuels to meet increasing global energy demands. Biomass derived fuels or bio-fuels, such as ethanol and butanol, are thought to offer the only renewable liquid alternatives to petroleum based transportation fuels. Although ethanol has long been recognised as a typical bio-fuel, butanol is also being due to several advantages it has over ethanol as a liquid fuel. The production of butanol by acetone, butanol and ethanol (ABE) fermentation using mainly Clostridium acetobutylicum and C. berjerinkii has been used by industry for decades. However, ABE fermentation was replaced by cheaper petrochemical methods in the 1920's although by 1945 the ABE fermentation became second in importance only to ethanol production by yeast. Unfortunately, by the 1960's ABE fermentation was no longer in use industrially because of the high cost of substrate, low productivity and low solvent concentration due to butanol toxicity to the production strains, low yield, and high solvent recovery cost. Although recent advances in the use of cheaper and more abundant raw materials, strain developments through genetic engineering combined with advanced fermentation, and product recovery technologies are critical for overcoming some of these obstacles, the economics of butanol production is still affected by the type and cost of raw material, the type of fermentation system used, the butanol recovery techniques, by-product credit, solvent yield, concentration and productivity. This paper reviews some current progress/developments in ABE production in terms of fermentation technology, strain development, novel upstream and downstream processing in an attempt to make the ABE fermentation economically competitive and environmentally favorable.
