Biofuels & Bioenergy

Concerns over the economics of proven fossil fuel reserves, in concert with government and public acceptance of the anthropogenic origin of rising CO2 emissions and associated climate change from such combustible carbon, is driving academic and commercial research into new sustainable routes to fuel and chemicals. Catalysis has a rich history of facilitating energy efficient, selective molecular transformations, and in a post-petroleum era will play a pivotal role in overcoming the scientific and engineering barriers to economically viable, and sustainable, biofuels derived from renewable resources. Biodiesel is one of the most readily implemented and low cost, alternative source of transportation fuels to meet future societal demands. However, current practices to produce biodiesel via transesterification employ soluble acids and bases, resulting in costly fuel purification processes and undesired pollution. Heterogeneous acid and base catalysts, able to transform undesired free fatty acid (FFA) impurities and naturally-occurring triglycerides within algal or plant oils into clean biodiesel, can dramatically improve process efficiency. The microporous nature of conventional catalysts hinders their application to converting bulky and viscous plant/algal bio-oil feed streams. We show how advances in the rational design of nanoporous solid acid and base catalysts, and their utilisation in novel continuous reactors, can deliver superior performance in the energy-efficient esterification and transesterification of bio-oil components into biodiesel.