Lithium Zirconate as a Selective and Cost-Effective Mixed Metal Oxide Catalyst for Glycerol Carbonate Production
2020
Kaur, Avneet | Ali, Amjad
Alkali and alkaline metal (Li, Na, K, Ca, and Mg)-loaded zirconium oxide catalysts were prepared by the wet impregnation method. All the prepared catalysts were employed as active heterogeneous catalysts for the transesterification of glycerol (GL) with dimethyl carbonate (DMC) producing glycerol carbonate (GLC). The catalyst with 20 wt % loading of Li on ZrO₂ showed a maximum catalytic activity with 100% selectivity toward GLC. The structure and basic properties of the prepared catalysts were studied by X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and CO₂-temperature programmed desorption techniques. The effect of various reaction parameters like catalyst concentration, reaction temperature, and the molar ratio of reactants on the GLC yield was also studied. For the first time, the reaction product was quantified using the ¹H NMR technique. Considering the less availability of the kinetic study of the transesterification of GL with DMC, kinetic parameters were also studied. The Li/ZrO₂-catalyzed transesterification reaction appeared to follow second-order kinetics with an activation energy (Eₐ) of 93.7 kJ mol–¹. Thermodynamic parameters like enthalpy (ΔH⧧), entropy (ΔS⧧), and Gibbs free energy (ΔG⧧) of the reaction were also determined.
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