Graphitic carbon nitrides: Efficient heterogeneous catalysts for biodiesel production

Abstract

Abstract Biodiesel remains one of the most promising sustainable alternatives to fossil fuel-derived energy; however, current process limitations and steep production costs associated with the use of homogeneous catalysts have limited global-wide acceptance and adoption. While heterogeneous catalysts have been put forth as suitable alternatives, they suffer from numerous drawbacks including high metal content and cost. As such, the search for novel and inexpensive alternatives is currently underway. Graphitic carbon nitride macrostructures have been widely investigated for photocatalytic applications yet their role in driving chemically-catalyzed reactions remains relatively unexplored. Herein, we synthesized and investigated the use of bulk, fiber, acid- and thermal-treated carbon nitrides as heterogeneous catalysts for the transesterification of canola oil to biodiesel. A conversion of 96% was achieved using 1 wt% catalyst loading, a low oil to methanol ratio of 1:24 and a reaction temperature and time of 150 °C and 3 h, respectively. Carbon nitrides offer a high thermal stability, cost effective and metal-free alternative to the many proposed metal-containing heterogeneous catalysts for biodiesel production, while maintaining high biodiesel conversions of >90%.