Pillared HMCM-36 zeolite catalyst for biodiesel production by esterification of palmitic acid

Abstract

Layered MWW zeolite has been studied for swelling/pillaring using CTAB and silica as swelling and pillaring reagents, respectively to synthesize pillared MCM-36 material. The swelling/pillaring efficiency was evaluated based on their X-ray diffraction, N 2 -physisorption, scanning electron microscopy and FTIR spectra after pyridine adsorption as indicator for acidity measurements and catalytic potential. There was an overall decrease in acid site concentration due to incorporation of inert silica pillars. However, after ion exchange, mesoporous HMCM-36 zeolite with the highest BET surface area showed increased Brönsted and Lewis acid sites compared to the MCM-22, suggesting enhanced accessibility of acid sites for bulky reacting molecules. MCM-22 and MCM-36, as well as the ion exchanged HMCM-22 and HMCM-36 samples were tested for esterification of palmitic acid with methanol. The HMCM-36 catalyst showed high activity in palmitic acid esterification with methanol. This catalyst can be readily separated from the reaction system for re-use for at least four cycles without losing any activity suggesting potential industrial applications in biodiesel synthesis.