Synthesis and characterization of calcium methoxide as heterogeneous catalyst for trimethylolpropane esters conversion reaction

Trimethylolpropane (TMP) esters are potential biodegradable basestock for biolubricant. In order to attain environmental benignity, attention has been focused on utilizing heterogeneous catalysts for production of TMP esters. Alkaline homogeneous catalysts tend to react with free fatty acids to produce unwanted soap, thus reducing the overall product yield. This study had focused on the synthesis of calcium methoxide and investigating its potential as heterogeneous catalyst for the transesterification of TMP and palm oil methyl esters (POME) to TMP esters. The performance of synthesized calcium methoxide as a catalyst was examined by characterizing it through some instrumental techniques. X-ray diffraction (XRD) showed calcium methoxide has been successfully synthesized. Scanning electron microscopy (SEM) displayed thermally resistant surface structure with good porosity; BET showed high surface area; particle size analysis evidenced reasonable size of catalyst particles; and thermogravimetry (TGA) revealed good thermal stability of synthesized calcium methoxide. Moreover, the catalyst was found to possess mesoporous surface by pore size analysis through Barrett–Joyner–Halenda (BJH) method. The results of transesterification reaction indicated satisfactory catalytic activity of synthesized calcium methoxide and the TMP triesters yield obtained was 80.35% after 2 h, 87.48% after 4 h, 91.30% after 6 h and 92.38% after 8 h reaction time.

Possible mechanism for transesterification of POME with TMP catalyzed by calcium methoxide.Figure optionsDownload high-quality image (76 K)Download as PowerPoint slideHighlights
► Trimethylolpropane esters are promisingly utilized as biolubricant basestock.
► Calcium methoxide was synthesized to use as heterogeneous catalyst for trimethylolpropane esters conversion.
► Calcium methoxide showed effective catalytic properties for transesterification reaction.
► An effective yield of trimethylolpropane triesters was obtained with using calcium methoxide as heterogeneous catalyst.