Catalytic behavior of sulfated zirconia supported on SBA-15 as catalyst in selective glycerol esterification with palmitic acid to monopalmitin

Abstract

An active SBA-15 supported sulfated zirconia catalyst was synthesized by urea hydrolysis method and characterized using N2 adsorption–desorption, SEM, TEM and EDX analyses. The catalyst was used in glycerol esterification with palmitic acid under continuous nitrogen flow and the performance was demonstrated based on palmitic acid conversion and monopalmitin yield. Effects of reaction conditions such as temperature (160–180 °C) and catalyst loading (1–3 wt. %) were elucidated and correlated with the characteristics of the catalyst. Incorporation of SZ into SBA-15 clearly improved the conversion of palmitic acid and monopalmitin yield. Increases in reaction temperature and catalyst loading increased the conversion of palmitic acid but the yield of monopalmitin was limited to less than 50% due to the pore characteristics that limited the diffusion of bulky molecules into the pore. On top of that, high palmitic acid conversion (86%) with monopalmitin yield of 43% was achieved in 3 h at 170 °C using 2 wt. % of SZSBA-15 catalyst. Moreover, the SZSBA-15 catalyst could be reused for up to four times without significant loss of the catalytic activity.