Catalytic characteristics and parameters optimization of the glycerol acetylation over solid acid catalysts

The acetylation of glycerol over different solid acid catalysts were investigated using a slurry reactor. Amberlyst-15 showed high activity as well as high selectivity towards diacetin and triacetin. The different catalytic activities between various catalysts were explained in terms of acid sites, pore diameter, and hydrophilic properties. The consecutive reaction of glycerol acetylation and the “steric effect” for the products was confirmed. Both the molar ratio of acetic acid to glycerol (AA/G molar ratio) and the temperature had positive effects on the glycerol conversion and the selectivity towards higher esters. However, the AA/G molar ratio was the more influential factor than the temperature, especially for improving the combined selectivity of diacetin and triacetin. At the optimal operating conditions (AA/G molar ratio 9/1 and 110 °C), the glycerol conversion predicted by the nonlinear models is 98.47%, and the corresponding selectivity is 8.65%, 46.56%, 44.79%, and 91.35% towards MAG, DAG, TAG, and DAG + TAG, respectively, all of these values are close to the experimental data.