Free sterols from acid hydrolysis of steryl glucosides

Abstract

Steryl glucosides (SG) are a group of insoluble chemicals in biodiesel. Steryl glucosides may cause clogging in production line and even small amounts of them may also cause low storage stability of biodiesel and plugging in a diesel engine. Therefore, an additional separation step is required to remove these contaminants. Since steryl glucosides have low solubility in many organic solvents, it is difficult to utilize the solid waste generated from the separation. Transformation of steryl glucosides to the form that are more soluble in general organic solvents should increase feasibility of utilization of the solid waste. In this study, hydrolysis of steryl glucosides to free sterols (FS) was investigated using nontoxic organic acid as catalyst. The hydrolysed products obtained from citric, lactic, and acetic acids were identified using a gas chromatograph connected with a mass spectrometer (GC-MS). The amounts of steryl glucosides and free sterols were also measured to compare efficiency of the catalysts. The most suitable catalyst was selected according to conversion of steryl glucoside (X <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SG</sub> ), selectivity to free sterols (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FS</sub> ), and yield of free sterols (Y <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FS</sub> ). To determine important parameters effecting the steryl glucosides conversion, the reaction test was performed with the selected catalyst at various operating condition.