Biodiesel Carbonaceous Nanoparticle-Supported Potassium Carbonate as a Catalyst for Biodiesel Production via Transesterification

This study primarily focuses on the development and optimization of a high-efficiency catalyst for biodiesel production. Potassium carbonate-supported solid catalysts were synthesized using soot as the support material via an equal-volume impregnation method. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses confirmed the successful deposition of potassium carbonate onto the soot surface, resulting in uniformly dispersed spherical nanoparticles on the catalyst. The catalytic performance was evaluated through single-factor experiments, assessing the effects of catalyst loading, alcohol-to-oil molar ratio, reaction temperature, and reaction time on the transesterification reaction. The maximum biodiesel yield obtained from the Single-factor experiments was 95.29% under the optimal conditions of 6 wt% catalyst loading (relative to oil), alcohol-to-oil molar ratio of 14:1, reaction temperature of 60 °C, and reaction time of 3 h. Furthermore, response surface methodology (RSM) using a four-factor, three-level Box–Behnken design (BBD) was employed to systematically analyze the interaction effects of these variables on the biodiesel yield. The optimized conditions identified by RSM were 61.1 °C, 3.3 h, alcohol-to-oil molar ratio of 14.2:1, and 6.1 wt% catalyst dosage, yielding 95.37% biodiesel conversion. These findings demonstrate that the soot-supported potassium carbonate catalyst developed in this study exhibits excellent catalytic activity, offering a novel catalyst system for industrial biodiesel production with significant academic and practical potential.