Optimization of microwave-assisted glycerol esterification into fuel additives using a bicontinuous concentric lamellar silica catalyst

Glycerol esterification using a bicontinuous concentric lamellar silica catalyst (SiO 2 BCL) under microwave irradiation was investigated as a route to produce acetin-based oxygenated fuel additives. The SiO 2 BCL catalyst exhibited an amorphous silica framework, concentric lamellar morphology, accessible mesoporosity, and weak-to-moderate acid sites, as confirmed by XRD, FTIR, FE-SEM, N 2 adsorption–desorption, BJH analysis, and NH 3 -TPD. Response surface methodology based on a central composite design was used to optimize the effects of the glycerol-to-acetic acid molar ratio, reaction time, and microwave power on monoacetin (MAG), diacetin (DAG), triacetin (TAG), and total glycerol esterification (GE). The optimum conditions were a glycerol-to-acetic-acid molar ratio of 1:8, a reaction time of 360 min, and a microwave power of 450 W, yielding 13.53% MAG, 31.11% DAG, 6.98% TAG, and 51.62% GE. The predicted and experimental values showed good agreement, confirming the reliability of the developed models. In addition, recyclability tests demonstrated that the SiO 2 BCL catalyst maintains stable activity over four consecutive cycles, with no significant loss of catalytic activity. The esterification product showed potential as an oxygenated fuel additive, particularly at low additive concentrations, with the caveat that further purification is required before practical fuel application. Overall, these findings demonstrate the potential of SiO 2 BCL as a reusable catalyst for the microwave-assisted valorization of glycerol via esterification.