Catalytic solid derived from residual bean husk biomass applied to sustainable biodiesel production: preparation, characterization, and regeneration study

Abstract

This study investigates the use of bean husks as a precursor for the synthesis of an efficient and regenerable catalyst, with the aim of offering an economical and sustainable alternative for biodiesel production. Residual bean shell biomass (RBBH) was calcined at different temperatures (350–500 °C) and times (1–4 h) to determine the optimum synthesis conditions. The catalyst obtained was characterized by various methods, such as X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and Thermogravimetric Analysis (TG/DTG). The results showed that the catalyst contains metal oxides and carbonates as active sites. In addition, the influence of reaction conditions was evaluated in the ranges of temperature (60–120 °C), time (0.5–2.5 h), MeOH : oil molar ratio (12 : 1–28 : 1) and catalyst concentration (2–10% by weight). The maximum ester content (97.6%) was achieved at 120 °C, 2 h, a MeOH : oil molar ratio of 20 : 1 and 8% catalyst. After partial deactivation of the solid catalyst, it was regenerated with KOH, yielding biodiesels with an ester content of over 75% in three consecutive cycles, demonstrating its efficiency and potential for continuous use.