Optimization of Biolubricant Synthesis Using Heterogeneous Catalysis: A Response Surface Methodology Approach

In this study, KIT-6, a cubic mesoporous silica with an Ia3d structure, was modified with varying amounts of zirconium and sulfate groups and used as a catalyst for biolubricant synthesis through the esterification of oleic acid and trimethylpropane (TMP). Characterization by Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction (confirmed the successful incorporation of zirconium and sulfate groups without altering the primary mesoporous structure. The reaction conditions were optimized using response surface methodology with variables including temperature, oleic acid/TMP ratio, catalyst concentration, and catalyst type. The optimized conditions (160 °C, 2.0% catalyst, 3:1 oleic acid/TMP ratio, and KIT-6(10) as the catalyst) resulted in an 86.0% conversion yield, confirmed by nuclear magnetic resonance 1H NMR analysis. Postreaction analyses demonstrated the structural stability of the catalyst under reaction conditions, indicating its suitability for multiple applications. This work highlights the potential of modified KIT-6 in catalysis, offering insights into reaction efficiency and catalyst stability.