Butanol as a drop-in fuel: a perspective on production methods and current status

The rising fossil fuel prices as well as negative climatic conditions caused by fossil fuel emissions have prompted technologists and scientists to develop alternative value-added fuels. These fuels can be produced from renewable bio-based materials and have less negative impacts on the environment. Much attention has been drawn to advanced fuels such as bio-based butanol, which is considered a promising fuel compared to ethanol. Its properties such as low volatility, less ignition problems and high inter-solubility make it an ideal drop-in fuel for conventional vehicles. This type of fuel can be utilised either in pure or blended form with petrol or diesel. Conventionally, butanol is produced through the acetone–butanol–ethanol (ABE) process using mainly Clostridium species to ferment sugars obtained from biomass. This method makes use of sustainable/cost-effective bacteria that are easily accessible. Alternatively, butanol can be directly produced from bio-based ethanol through aldol condensation using metal oxides/hydroxyapatite catalysts. Catalyst synthesis involves short reaction times, but high reaction temperatures. This chapter highlights the use of butanol as a fuel, reviews different methods employed and discusses current status and potential for future prospect