Biomass waste-derived catalysts for biodiesel production: Recent advances and key challenges

Biomass -derived catalysts are being intensively studied as potential replacements for traditional chemical catalysts in the sustainable generation of biodiesel because of their unique combination of characteristics; catalytic activity, low-cost, plentiful supply and ecologically friendly and efficient manufacturing procedures. This critical review discusses the recently reported approaches that have been used (mostly since 2016) towards cost-effective and environmentally benign solid base/acid/acid-base catalysts from a range of biomass. Sources include shells, animal bones, and plants. Outlined alongside the push for optimized conversion and yield is the increasing trend for enhanced catalyst reusability and recyclability. Outstanding technical problems associated with catalyst preparation or stability, or waste generation are considered individually. The outlook for solving each of these is discussed, as is the potential of biomass -derived catalysts and the biodiesel they produce to develop the fields of fuel synthesis and energy use. Overall, this review aims to assess the viability of biomass -derived catalysts in the commercial sector and the most promising routes for transferring new technologies from the academic environment to industry.