The effect of process parameters and catalyst support preparation methods on the catalytic efficiency in transesterification of sunflower oil over heterogeneous KI/Al2O3-based catalysts for biodiesel production

The essence of this study is synthesis of a newly developed and efficient heterogeneous catalyst based on aluminum oxide support promoted with potassium iodide (KI) as active dopant responsible for pronounced catalyst activity. Modified sol-gel, reflux and hydrothermal method were used for synthesis of aluminum-oxide support using aluminum isopropoxide as a precursor. The gamma-Al2O3 support and KI/gamma-Al2O3 catalyst samples were examined by various experimental techniques. Effects of several operational parameters were considered and those are: methanol to sunflower oil molar ratio, catalyst loadings, reaction time and reaction stirring rate. The obtained results indicated that modified sol-gel method for synthesis of gamma-Al2O3 catalyst support is the most favorable for obtaining the catalyst with superior catalytic performances in transesterification of sunflower oil. A maximum conversion (triglycerides to methyl esters) of 99.99% was achieved using the SG-KI/gamma-Al2O3-770 catalyst under following optimal process parameters: 15:1 methanol to sunflower oil molar ratio, 2.5 wt% catalysts loading, 600 rpm stirring rate and 4 h of the reaction run.