Selective conversion of glycerol to lactic acid by CaO y Al2O3 supported catalyst
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Date
2018-03-01
Authors
Kartina Mbong
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Abstract
The biodiesel production has been developing rapidly in Malaysia and it generates a surplus of crude glycerol as the primary co-product. Based on the current situation, the conversion of glycerol to higher value-added chemicals like lactic acid has attracted many researchers to ensure the economic sustainability of the biodiesel industry. In the present work, CaO supported on alumina, γ-Al2O3 catalyst was synthesized with different CaO loadings (20-50 wt. %) and the final calcination at optimum temperature was 700 °C. The synthesized catalyst were then characterized by means of surface analysis, SEM, TEM, XRD, EDX, FTIR, TGA and N2 adsorption-desorption isotherm. The characteristics of the catalysts were correlated with the catalytic activity in glycerol etherification and the performance demonstrated based on the glycerol conversion and lactic acid yield. It was found that high yield of lactic acid was identified by using 30CaO/γ-Al2O3 catalyst which was prepared using 30 wt.% of CaO loading and calcined at 700 °C in the production of lactic acid from glycerol. Effects of reaction condition such as catalyst loadings (5-20 wt. %), reaction temperature (270-330 °C), reaction time (0.5-4 h) were also explained and correlated with the characteristics of the catalysts. On top of that, the best reaction conditions were obtained at 10 wt. % of catalyst loading, a reaction temperature of 290 °C and a reaction time of 2 h. Under these conditions, using 30CaO/γ-Al2O3 catalyst, 95 % of glycerol conversion and 49 % of lactic acid yield were obtained. In terms of reusability, this catalyst was reusable for up to 3 times in this reaction with decrease from 95% to 73% for glycerol conversion, while decrease from 47% to 27% in lactic acid yield in the catalytic activity. The kinetic study of lactic acid formation was successfully conducted with a first order kinetic model and the activation energy of reaction of 61.730 kJ/mol was determined. As a conclusion, 30CaO/γ-Al2O3 catalyst showed good activity and it is an active catalyst that is suitable to be used in the reaction involving glycerol.