Catalytic evaluation of Li and K supported on CaO in the transesterification of triolein, triestearin, and tributyrin

CaO-supported Li and K catalysts were studied for transesterification reactions. The CaO was obtained from calcined commercial limestone. The catalysts were impregnated with LiNO 3 and KNO 3, reaching a loading of 3 wt.% of alkali metal. The synthesized catalysts were characterized by thermogravimetric analysis, X-ray diffraction, and Hammett indicators. The catalytic transesterification evaluations of tributyrin, triestearin, and triolein with methanol were carried out with methanol/triglyceride molar ratio of 20:1 and 3 wt.% of catalyst at 60 °C for one hour. It was found that the strength of the alkaline sites increased when alkali metal was added to the support since these metals prevented the formation of Ca(OH) 2 . The Li/CaO catalyst presented higher basic strength and higher catalytic activity. It was observed that short-chain triglycerides were found to be more reactive than long-chain and unsaturated ones; likewise, saturated chain triglycerides are more reactive than unsaturated ones due to fewer interactions with the active sites. Finally, potassium avoided the lixiviation of the catalysts to the liquid phase. Graphical abstract