A practical approach for enhanced biodiesel production using organic modified montmorillonites as efficient heterogeneous hybrid catalysts

Abstract

Developing efficient and environmentally friendly heterogeneous catalysts for sustainable biodiesel preparation is considered a viable manner to meet global energy demand and alleviate environmental concerns. In this work, a series of novel mesoporous organic–inorganic hybrid clay materials ILs-OMt-x (x, the use of pyrrole mass, x = 0.4, 0.6, and 0.8 g), were fabricated by pyrrole in situ polymerization utilizing ionic liquid (IL)-grafted biocompatible montmorillonite (Mt) as a modified matrix under relatively mild conditions. Among these clay materials, it was determined that ILs-OMt-0.6 had favorable physicochemical properties, including large specific surface area (S_BET, 80.41 m² g⁻¹), layered mesoporous structure (12.28 nm), multiple acid sites, and relatively strong acid intensity (1.63 mmol g⁻¹). As a result, ILs-OMt-0.6 showed outstanding catalytic performance in biodiesel preparation, and the highest biodiesel yield of 97.02% was obtained after single-factor and response surface methodology (RSM) optimization (6.4 wt% catalyst dosage, 15.2 : 1 molar ratio of methanol to oleic acid (OA), 6.3 h, 83.0 °C). In addition, kinetics study further confirmed its lower activation energy compared with pristine Mt and commercial resin Amberlyst-15, and a possible esterification mechanism was also proposed. Importantly, ILs-OMt-0.6 showed excellent substrate versatility, displaying satisfactory catalytic performance in trans(esterification) of other fatty acids and raw non-edible oils. It is worth mentioning that the physicochemical properties of as-synthesized biodiesel conformed with international standards, and its life-cycle cost (LCC) indicated the good economic viability of ILs-OMt-0.6 for efficient catalytic biodiesel production. This study reveals a promising application path of novel hybrid materials with favorable physicochemical properties in biodiesel production and provides new paths for fabricating Mt-based catalysts with high efficiency and stability for the sustainable development of liquid biomass refining technology.