ESTERIFICATION OF GLYCEROL OVER COMMERCIAL CATALYSTS AND Cu-Ni/C CATALYST

Abstract

Enhanced biodiesel production has resulted in production of surplus amount of glycerol. This trend of glycerol production has not only flooded the current market of glycerol but also has negatively affected the viability of biodiesel. Finding new innovative solution for glycerol transformation into high value-added products can contribute to economics of biodiesel production. Esterification of glycerol using acetic acid that produce monoacetin, diacetin and triacetin can be very promising route for utilization of surplus amount of glycerol because these higher acetylated products of glycerol have very good properties to use as fuel additives and in other applications. In earlier studies, several catalysts have been proposed and tested for esterification of glycerol. So far, Amberlyst-21 and copper-nickel based catalyst have not been tested for esterification of glycerol. Amount of Cu and Ni was 2.5% in Cu-Ni/C catalyst. Here in this study, the physiochemical properties of the catalysts, such as specific surface area, X-ray diffraction (XRD), scanning electron microscopy and Fourier transform infrared spectroscopy of -various catalysts was also studied. Activity of various catalysts was compared. Esterification of glycerol was carried out using Amberlyst-15, Amberlyst-21, ZSM-5, Cu-Ni/C. Amberlyst-15 was found to the most active catalyst. Amberylst-21 and Cu-Ni/C were found to have activity comparable to each other. Maximum conversion of 99.2% was obtained for Amberlyst-15 with selectivity to glycerol monoacetate, glycerol diacetate, glycerol triacetate were 13.3%, 52.2% and 34.5% respectively. Among all, ZSM-5 was the least active catalyst with conversion of 75.7% and selectivity to monoacetin, diacetin and triacetin were 54.1%, 42.1 and 3.8% respectively. To study effect of time, reaction was performed for 3 h. - To study the effect, temperature was varied from 80°C to 120°C, glycerol to acetic acid mole ratio was varied from 1:9.5 to 1: 5 and catalyst loading was varied from 0.05 to 0.15 g for Cu-Ni/C and 0.1 to 0.5 g for other catalysts. All reactions were performed for 3 h. Amberlyst-15 showed different behavior compared with other catalyst. This was because of highest activity of Amberlyst-15 among all catalyst used.