Carbon Nitride-Based Nanomaterials as a Sustainable Catalyst for Biodiesel Production

Abstract

In this work, we investigated a series of carbon nitride-based nanomaterials (CNs), i.e., H-PHI, mpg-C3N4, PCN, Na-PHI, Mg-PHI, CN-OA-m, and LiK-PHI, as candidate catalysts for biodiesel synthesis. The heterogeneous catalyst design based on CNs, with tunable catalytic sites and inexpensive syntheses, can allow biodiesel production to become a more sustainable process, helping to meet future energy demands. Transesterification of canola oil with methanol using LiK-PHI as a catalyst, under the optimized conditions, displayed the best performance for biodiesel production with 94% of yield and catalyst loading of 1.6 wt %. The outstanding performance exhibited by LiK-PHI is owed to this sample presenting the highest concentrations of basic sites, among the CN materials tested, directly correlated with the alkali metal content. This is an important information to understand the very nature of these basic active sites, which were exploited in this work to boost the catalyst efficiency among the best in the field. Moreover, the biodiesel produced under the best conditions, using LiK-PHI, was verified in relation to the number of esters and glycerides in this product. All values are within the values previously established by legislation, 97.6% ± 0.1 and 0.20%, respectively, which indicates the high quality of biodiesel produced.