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

Abstract

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 γ-Al2O3 support and KI/γ-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 γ-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/γ-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.