Efficient production of biodiesel from palm fatty acid distillate using a novel hydrochar-based solid acid catalyst derived from palm leaf waste

Authors: ALIYU, MUHAMMAD - Universiti Putra Malaysia; Moser, Bryan; ALHARTHI, FAHAD - King Saud University; RASHID, UMER - Universiti Putra Malaysia

Submitted to: Process Safety and Environmental Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/9/2024
Publication Date: 5/13/2024
Citation: Aliyu, M., Moser, B.R., Alharthi, F.A., Rashid, U. 2024. Efficient production of biodiesel from palm fatty acid distillate using a novel hydrochar-based solid acid catalyst derived from palm leaf waste. Process Safety and Environmental Protection. 187:1126-1139. https://doi.org/10.1016/j.psep.2024.05.040.
DOI: https://doi.org/10.1016/j.psep.2024.05.040

Interpretive Summary: This research reveals a new solid catalyst for production of biodiesel from low-cost, low-quality, non-food vegetable oils. The new, inexpensive, highly stable, biomass-based solid catalyst has important advantages over the common industrial catalysts used for production of biodiesel, such as easy removal, recoverability, re-usability, and avoidance of wastewater generation. Thus, biodiesel was produced in high yield from palm fatty acid distillate, a waste product of the palm oil industry. Overall, the catalyst could be recovered and reused five times without loss of activity. These results will be important to biodiesel producers, distributors, and end-users (customers) because a new catalyst was described that produces biodiesel with favorable fuel properties. This research may ultimately improve market penetration, availability, and public perception of renewable agricultural fuels such as biodiesel, thus affording greater national independence from imported petroleum-based fuels while enhancing rural economies.

Technical Abstract: To combat fuel shortages, pollution, and the exhaustion of natural oil resources, an environmentally friendly alternative to fossil fuels, such as biodiesel, is essential for meeting global transportation demands. A novel heterogeneous acid catalyst for production of biodiesel from low-cost, high free fatty acid feedstocks was synthesized in this study by activating and impregnating hydrochar from palm leaf (PL) waste with H3PO4 and H2SO4. Subsequently, the sulfonated catalyst was utilized for the esterification of palm fatty acid distillate (PFAD). FT-IR, XRD, FESEM, EDX, BET, TGA, and surface acidity methods were employed to characterize the acid catalyst. Using the one-variable-at-a-time (OVAT) technique, the optimized reaction conditions for esterification of PFAD using the hydrochar-based catalyst were 4 wt% catalyst loading, 353.15 K reaction temperature, 4 h reaction time, and 18:1 methanol: PFAD molar ratio. At these conditions, a maximum biodiesel yield of 93.56% was achieved. The catalyst exhibited excellent reusability and stability throughout five reaction cycles, maintaining biodiesel yields above 80% after each cycle. Analysis of the fuel properties revealed that the biodiesel derived from PFAD met the physiochemical criteria outlined in ASTM D6751, the American biodiesel standard. The kinetic study revealed that the esterification reaction followed pseudo-first-order kinetics with an activation energy (Ae) of 23.70 kJ/mol.Furthermore, the thermodynamic enthalpy and Gibbs' free energy of esterification were 20.9 and 33.41 kJ/mol, respectively, indicating that the reaction was an endothermic and non-spontaneous process.