Green Nanocatalysts for Sustainable Biodiesel Production and Process Intensification

Abstract

Biodiesel is a promising renewable fuel, but its large‐scale commercialization is constrained by catalyst inefficiency, feedstock variability, and high production costs. Green nanocatalysts have emerged as sustainable alternatives owing to their high surface area, tunable acid–base properties, defect‐rich surfaces, and enhanced catalytic activity for esterification and transesterification. This review critically examines recent advances in bioresource‐derived metal oxide, magnetic, carbon‐based, and hybrid nanocatalysts, emphasizing the structure–activity relationships that govern catalytic performance. The roles of oxygen vacancies, surface defects, and active sites in alcohol activation and reaction pathways are highlighted. Catalyst deactivation mechanisms, including agglomeration, carbonation, metal leaching, fouling, and regeneration limitations, are also examined. Furthermore, process‐intensification strategies, particularly ultrasound‐ and microwave‐assisted transesterification, are evaluated for their potential to improve mass transfer, reduce energy consumption, and enhance biodiesel productivity. Environmental sustainability, life‐cycle assessment, toxicity, fuel‐quality aspects, and techno‐economic feasibility are critically discussed to assess the industrial potential of green nanocatalysts. Current challenges related to scalable green synthesis, catalyst durability, operando characterization, and continuous‐flow processing are identified, and future research directions are proposed. This review provides an integrated framework for the rational design and industrial implementation of next‐generation green nanocatalysts for sustainable biodiesel production.