Process for the production of alcohols

The increased consumption of finite fossil raw materials raises the necessity to find ­alternatives for the production of basic chemicals and fuels. A sustainable procedure is the gas ­fermentation, where a synthesis gas (e.g. CO, CO₂, H₂) is converted by microorganisms in a bioreactor. The synthesis gas is available as a by-product of the agriculture, iron-, oil- and ­chemical ­industry and can thereby be recycled. Gas fermentation is a relatively new field in the cultivation of ­bacteria. In this repect Clostridium carboxidivorans is of special ­interest since it is one of the few ­acetogenic bacteria which is able to produce longer chained ­carbon ­compounds like ­butanol and hexanol directly from synthesis gas, besides acetic acid and ­ethanol.

This technology provides an opportunity for product formation where different cell-regulated phases are present by using a cascade of two serially connected stirred-tank reactors. Both reactors are constantly supplied with synthesis gas (CO : CO₂ = 60 : 40). The first reactor is controlled at a pH value of 6 and thereby provides optimal conditions for anaerobic growth of biomass as well as production of acetat and ethanol. A part of the medium containing the bacertia and their products is constantly transfered to the second reactor, where a pH value of 5 is adjusted. In reactor two, cells do not grow anymore and convert acetat in ethanol, butanol and hexanol. This technology provides a de novo synthesis for long-chain alcohols.

• Utilization for small application as well as for industrial scale up
• Possible adaptation for the production of other bacteria & chemicals

Prototype