The Effect of Multi-Anion Hydrotalcite Catalyst and Amount of CO3 2- Anion Towards Selective Etherification of Glycerol to Diglycerol

The rapid expansion of biodiesel production has resulted in a substantial surplus of glycerol. To maintain balance in the global glycerol market, it is essential to advance research focused on converting glycerol into high-value products. This study demonstrates the conversion of glycerol into diglycerol using a basic-catalyzed etherification reaction. Multi-anion hydrotalcite was studied by combining the added anion sources (NO3 - and SO42-) with the main anion source (CO32-). The tri-anion (CO3 NO3 SO4) hydrotalcite sample demonstrated a 92.73% selectivity in the etherification process aimed at producing diglycerol over a 16-hour period. Enhancing the concentration of anions within the hydrotalcite layers can boost basicity, thereby enhancing catalytic activity. Of the samples tested, the one with a 50% concentration of CO32- anion emerged as the most effective for etherification, surpassing the performance of the 30% and 70% variants. The optimal proportion of the primary anion source (CO32-) plays a crucial role in maintaining the stability of hydrotalcite throughout the reaction. Thus, the appropriate amount of main anion source (CO32-) could influence the stability of hydrotalcite during reaction. This study suggested that the modification of hydrotalcite might improve the catalytic activity of hydrotalcite during reaction. For future use, this study is highly potential in overcoming the glycerol surplus problem and broadens the utilization of glycerol in many industries.