Biochar-derived heterogeneous catalysts for biodiesel production

Population increase, urbanization and industrialization induce a drastic need for energy. Actually, fossil fuel resources are heavily exploited to meet the energy demand and result in the emission of greenhouse gases. Alternatively, biodiesel is a renewable fuel produced by transesterification of biomass lipidic feedstocks. Biodiesel is a renewable fuel that can replace fossil diesel. Short-chain alcohols and efficient catalysts are required for biodiesel production. For instance, biochar can be used as a heterogeneous catalyst for biodiesel production owing to its high surface area and porosity. Biochar is a low-cost, carbon-rich material produced by pyrolysis of plant biomass. Here, we review the production, activation, and application of biochar, with focus on characteristics of biochar-derived catalysts, such as surface chemistry, thermal stability, total acidity or basicity, structural morphology, and elemental composition. We also present the developments of biochar-based catalysts from various biomass sources for biodiesel production.