Highly active and efficient Cu-based hydrotalcite-like structured materials as reusable heterogeneous catalysts used for transcarbonation reaction

Abstract

A series of robust and efficient Cu-Al hydrotalcite-like compounds (HTLc) as catalysts were prepared by the simple precipitation method with different Cu/Al molar ratios and investigated for the transcarbonation of glycerol with dimethyl carbonate (DMC) for glycerol carbonate (GC) synthesis in a batch reactor. The structural and textural properties of the Cu-Al (HTLc) catalysts were analyzed by several methods like N₂-sorption, SEM-EDX/TEM, XRD, FTIR, CO₂-TPD, TGA/DTA and ICP-OES. It was found that the transcarbonation of glycerol is directly dependent on the strong basic sites of the catalysts. The Cu/Al molar ratio has easily tuned the glycerol conversion and the GC yield. Among all synthesized catalysts, the Copper-Aluminum (3Cu-Al@500) catalyst showed excellent catalytic activity for a glycerol conversion (96%) and a GC yield (86%) with reaction rate (irrespective to glycerol) of approximately 0.106 mol L^-1 h^-1. Furthermore, the optimization of the reaction conditions (i.e. molar ratio of the reactants, catalyst mass, reaction time and temperature) and the reusability of the 3Cu-Al@500 catalyst for glycerol conversion and GC yield with TOF value were studied. In addition, the effect of stirring speed and particle size on the minimization of external and internal mass transfer resistance, respectively, was investigated.

Keywords: Cu-based hydrotalcite; Glycerol; Glycerol carbonate; Transcarbonation.