Reactivity of triglycerides and fatty acids of rapeseed oil in supercritical alcohols

Assessment of process variables on the use of macauba pulp oil as feedstock for the continuous production of ethyl esters under pressurized conditions

“…The solubility of free fatty acids at sub-or supercritical fluid conditions is greater than that of triacylglycerols, so the esterification reaction can proceed more easily (Warabi et al, 2004). Increased pressure favors the solubility of ethanol in oil.…”

“…Aiming to solve the drawbacks of processes using homogeneous catalysts and enzymes, non-catalytic reactions in pressurized medium using alcohols at sub-or supercritical conditions can be applied, as it allows for the simultaneous transesterification of triacylglycerides and esterification of free fatty acids, and hydrolysis of triacylglycerides when water is present in the reaction medium (Warabi et al, 2004, Kusdiana and. The fact that the alcohol is present under pressurized conditions in the reaction medium leads to higher solubility of the substrate, increasing reaction rates and ester yields .…”

Transesterification in Supercritical Conditions

“…The rate constants of saturated triglycerides were found to be faster than unsaturated triglycerides and slow down with increasing levels of double bonds in the triglyceride molecule (Rathore & Madras, 2007;Varma & Madras, 2006). However, saturated fatty acids have a slightly lower reactivity than the unsaturated fatty acids (Warabi et al, 2004). On the other hand, a second-order kinetic model with respect to both the triglycerides and alcohol concentrations has also been proposed (Diasakou et al, 1998;Song et al, 2008).…”

“…2003; Kusdiana & Saka, 2004a) and the reactivity of supercritical alcohols were all reported (Warabi et al, 2004). In 2004, the first supercritical transesterification of sunflower oil with ethanol and supercritical carbon dioxide in the presence of a lipase enzyme were investigated in a batch reactor (Madras et al, 2004).…”

“…For example, the esterification of free fatty acids with alcohols increases the fatty acid alkyl ester content in the biodiesel product, while the thermal cracking of unsaturated fatty acids decreases the esters content. The earlier research on supercritical transesterification mostly employed methanol as the reacting medium and reacting alcohol at the same time due to the fact that it has the lowest critical point and the highest activity (Warabi et al, 2004). Ethanol is also an interesting candidate because it can be industrially produced from renewable sources in many countries nowadays.…”