Synthesis of Fe2O3-supported lightweight expanded clay aggregate (LECA) via solution combustion: An Innovative and Cost-Effective catalyst for biodiesel generation

This study investigates the application of ultrasound-assisted Fe 2 O 3 supported on treated lightweight expanded clay aggregate (LECA), synthesized via the solution combustion method, as a catalyst for biodiesel production. The catalyst was characterized using various techniques, including XRD , FESEM , EDX , TEM , BET-BJH, and TPD-NH 3 . Characterization results indicated that the Fe(0.15)-LECA(U) catalyst exhibited a pore volume of 0.05 cm³/g, a surface area of 22.74 m²/g, and a well-dispersed Fe 2 O 3 on the support surface. TPD-NH 3 analysis revealed a significant presence of medium and strong acidic sites, with total acidic site concentrations of 0.736, 2.104, 0.939, and 0.412 mmol NH 3 /g at temperatures of 214.7, 350.6, 501.3, and 692.4°C, respectively. The high dispersibility of acidic sites increased the rate of reaction as in the condition of 3 wt.% catalyst loading, 95°C reaction temperature, 1-hour reaction time, and a methanol-to-oil molar ratio of 20, the catalyst achieved a remarkable biodiesel conversion of 98.49% with an apparent rate constant of 0.0218. Notably, a 2.02% decrease in conversion was observed after five consecutive reaction cycles, demonstrating the catalyst's excellent stability attributed to the strong bonding between Fe 2 O 3 and treated LECA facilitated by ultrasound treatment.