Evaluating cocoa pod ash as a heterogeneous catalyst for biodiesel production: The case of Fundo Gibaja, Quillabamba, Cusco

Abstract

Biodiesel production typically employs homogeneous catalysts due to their high activity and rapid reaction rate; however, there are gaps for technical and environmental improvement. Separating and recovering the catalyst is complex and necessitates subsequent washing and purification stages, which increase water consumption for biodiesel washing, the use of neutralization agents, and operating costs. Furthermore, it can promote saponification and reduce the sustainability of the process. Therefore, it is necessary to identify alternative, environmentally friendly, and low-cost catalysts, preferably heterogeneous, that maintain high conversion rates and facilitate their recovery and reuse. In this regard, cocoa pod husks, an abundant agricultural residue in Peru and worldwide, contain inorganic compounds with significant catalytic potential, such as potassium oxide (K2O). In this study, the residues were transformed into a heterogeneous catalyst by calcination at 700 °C for 4 hours. The catalyst was then characterized using the following analytical techniques: Energy Dispersive Spectroscopy (EDS) to identify the elements present, Fourier Transform Infrared Spectroscopy (FTIR) to confirm the presence of carbonates and associated functional groups, Scanning Electron Microscopy (SEM) to evaluate particle morphology and size, and Brunauer-Emmett-Teller (BET) spectroscopy to determine the specific surface area. Catalytic activity was evaluated at 20 minutes, 2%–3%, 1:15, and 200 rpm, achieving a biodiesel conversion rate of at least 96.2%. These results suggest viability and provide evidence for designing processes oriented towards the standardized criteria of ASTM D6751 and EN 14214.