SYNTOBU · Biological production of butanol from syngas

The global energy consumption has doubled over the last 30 years, sustained mainly by the use of fossil fuels. The potential depletion of these may leave our society at the edge of an energy crisis unless reliable alternative energy sources are developed. The current context has led to the investigation of alternatives, such as bio-fuels, a renewable energy source with carbon neutral contribution to global warming because they are generated from biomass or wastes. These can be converted to bio-fuels by different ways. One of the most common is the catalytic process Fischer-Tropsch (FT), which allows the conversion of carbon monoxide and hydrogen to liquid hydrocarbons. This process requires an initial stage of gasification to convert the wastes into a mix of CO2, CO and H2 called syngas. This gas contains also impurities (i.e. volatile sulfur compounds, tars, ammonia). The FT process is well established, but is complex and has high energetic requirements. Additionally, the process requires the use of catalysts, of high cost and elevated sensitivity to impurities. To protect them, syngas has to be pre-treated, although this is not always technically possible and economically feasible. Currently, alternatives to the FT process are being investigated. One of them is the production of ethanol and other bio-fuels using microorganisms as biocatalysts. The main advantage of these fermentative processes is the high specificity and yield. They are also conducted at temperatures slightly higher than room temperature, reducing the operational costs. Furthermore, the microorganisms have a high tolerance and adaptability to syngas contamination. The main aim of this project is to investigate the production of butanol from syngas. The study will characterise the process both kinetically and stoichiometrically and identify optimal operational conditions, as well as investigate the production of butanol in continuous mode under different bio-reactor configurations.