Attapulgite as a Potential Clay Catalyst in Biodiesel Production: Properties, Modifications, and Applications

Biodiesel, a renewable and eco-friendly alternative to fossil diesel, is primarily produced via the transesterification of vegetable oils or animal fats with short-chain alcohols, catalyzed by acidic or basic agents. Attapulgite, a naturally abundant magnesiumaluminum phyllosilicate clay, has emerged as a promising heterogeneous catalyst support owing to its high surface area, thermal stability, and low cost. This review synthesizes recent advancements in the use of attapulgite for biodiesel production, focusing on its structural properties, modification strategies such as acid treatment, elemental functionalization, metal loading, catalytic performance in transesterification and esterification reactions, and integration with emerging technologies. Key studies have demonstrated biodiesel yields exceeding 90% under mild conditions, such as 60°C, 6 wt% catalyst, and 9:1 methanol: oil ratio, with enhanced reusability up to 10 cycles. However, challenges such as limited basicity, mass transfer limitations in three-phase systems, and deactivation by impurities remain. Future prospects include attapulgite-based composites, microwave-assisted processes, and life cycle assessments for scalable and sustainable biodiesel production. This comprehensive analysis highlights the potential of attapulgite to reduce production costs by 2030% compared to homogeneous catalysts, paving the way for industrial adoption. Keywords – Attapulgite, Biodiesel, modification, transesterification