Esterification of Glycerol With Oleic Acid Over Hydrophobic Zirconia-Silica Acid Catalyst and Commercial Acid Catalyst: Optimization and Influence of Catalyst Acidity.

Pei San Kong,Yolande Pérès,Mohamed Kheireddine Aroua,Wan Mohd Ashri Wan Daud,Patrick Cognet

doi:10.3389/fchem.2019.00205

Abstract

Catalytic esterification of glycerol with oleic acid (OA) was optimized over hydrophobic mesoporous zirconia-silica heterogeneous acid catalyst (ZrO2-SiO2-Me&Et-PhSO3H) and benchmarked with commercial catalysts (Aquivion and Amberlyst 15) in order to examine the effect of catalyst acidity on conversion, yield and product selectivity. The process optimisation results showed an 80% conversion with a 59.4% glycerol mono-oleate (GMO) and 34.6% glycerol dioleate (GDO) selectivities corresponding to a combined GMO and GDO selectivity of 94.8% at equimolar OA-to-glycerol ratio, 160°C reaction temperature, 5 wt% catalyst concentration with respect to the OA weight and 4 h reaction time. This work reveals that the hydrophobic and mild acidic ZrO2-SiO2-Me&Et-PhSO3H catalyst outperformed Amberlyst 15 and Aquivion with a yield of 82% and GMO selectivity of 60%. It is found that catalyst acidity is a key parameter for catalytic activity and conversion rate. Nevertheless, high acidity/acid strength reduced the product yield in the glycerol esterification of OA.

Highlights

Glycerol mono, di-oleates (GMO, glycerol dioleate (GDO)) are lipids with amphiphilic, non-ionic and excellent emulsifying properties that widely applied in food, cosmetic, and pharmaceutical industries, and aqueous fiber finishing (Thengumpillil et al, 2002; Macierzanka and Szelag, 2004)
Results showed that Amberlyst 15 obtained a higher yield and selectivity for GDO and GTO (SGDO = 65% and SGTO = 12%) than those of the two other catalysts; this result can be attributed to the lower acidity strength of Amberlyst 15 (H0 = −2) than that of Aquivion (H0 = −12) and its larger pore size (28.8 nm) than that of ZrO2-SiO2-Me&EtPhSO3H (3.77 nm)
In this work the esterification of oleic acid with glycerol was conducted on ZrO2-SiO2-Me&Et-PhSO3H catalyst

Summary

Introduction

Di-oleates (GMO, GDO) are lipids with amphiphilic, non-ionic and excellent emulsifying properties that widely applied in food, cosmetic, and pharmaceutical industries, and aqueous fiber finishing (Thengumpillil et al, 2002; Macierzanka and Szelag, 2004). ZrO2-SiO2-Me&EtPhSO3H catalyst (3, 5, and 8 wt%) was used to investigate the effects of catalyst concentration on the conversion and selectivity of the catalytic glycerol esterification with OA at the constant operation parameters of 160◦C, equimolar ratio and 650 rpm.

Results

Conclusion