Interesterification of triglycerides with methyl acetate for biodiesel production using a cyclodextrin-derived SnO@γ-Al₂O₃ composite as heterogeneous catalyst

Abstract : Particle morphology and surface properties of metal oxides are topics of great importance in the field of heterogeneous catalysis. Herein, we have developed a molecular-colloidal coassembly approach combined with an ultrasonic-assisted precipitation method to fabricate SnO@γ-Al₂O₃ composites with tuneable pore size and well-defined octahedral-shape crystal structure. The supramolecular assemblies formed between the randomly methylated β-cyclodextrin (RaMeβCD) and Pluronic F127 were employed as template to tailor the size and shape of γ-Al₂O₃ nanoparticles and direct their assembly almost exclusively on the surface of micrometer-sized SnO single crystals. Results revealed that the cooperative action of the supramolecular template and γ-Al₂O₃ nanoparticles may have a critical effect on the growth and orientation of SnO microcrystals and ultimately determine their catalytic performance in the interesterification of rapeseed oil with methyl acetate. The compartmentalized SnO@γ-Al₂O₃ structures could achieve fatty acid methyl esters (FAME) and triacetin (TA) yields of 33.5% and 1.5% respectively after 30 min at 210 °C, exceeding by 38% the FAME yield of the commercial catalyst.