Sulfation of metal-organic framework (MOF) nanocatalyst for esterification of oleic acid with methanol to produce biodiesel

Abstract

Background: Metal-organic frameworks (MOFs) represent tremendous potential as heterogeneous catalyst in renewable energy production. In this study, biodiesel production using the modified MOF nanocatalyst was investigated in the esterification reaction. Methods: MOF nanocatalyst was prepared using solvothermal method and modified through sulfation process. The nanocatalysts was characterized by XRD, FT-IR, FE-SEM, TEM, N2 adsorption-desorption, and NH3 -TPD techniques. The performance of the nanocatalysts was evaluated in the esterification reaction of free fatty acid (FFA) at different operating conditions. Results: The results showed the high crystallinity, appropriate textural properties (995.6 m2 g-1), well-adjusted acidity, and high hydrophobicity. The sulfation degree of 4 cc g-1 resulted in the best nanocatalyst, which led to the highest FFA conversion (97%) at the optimal conditions: methanol to FFA ratio of 10:1, 3wt.% nanocatalyst, 160 °C, and 6 hours. Surprisingly, the developed nanocatalyst had a great reusability while the conversion reduction was only 8% after six sequence cycles. Conclusion: These results proved the high capability of the developed nanocatalyst in the esterification reaction to produce biodiesel.