Resumen de Solvent-free synthesis of glycerol carbonate catalyzed by Zn-Al mixed oxides promoted by La and Zr
Italo Oliveira Monteiro, Alexandre Barros Gaspar, Cristiane Assumpção Henriques
Glycerol is a sustainable raw material for synthesizing various chemicals, including glycerol carbonate. In this study, a series of Zn-Al-X (where X = La or Zr) mixed oxides derived from hydrotalcite-type precursors were investigated as heterogeneous catalysts for the production of glycerol carbonate via the transesterification reaction between glycerol (GLY) and dimethyl carbonate (DMC). The molar ratio Zn/Al in the catalysts was set at 2, while the content of the promoter (X/Al molar ratio) was set at either 0.02 or 0.3. Their physicochemical properties were characterized using inductively coupled plasma-optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), N2adsorption-desorption at -196 °C, and temperature-programmed desorption of CO2 (TPD-CO2). Solvent-free catalytic tests were conducted at 100 °C with a DMC:GLY molar ratio of 3:1. The reaction conditions were adjusted to compare all catalysts at low glycerol conversion levels (XG < 20%). Glycerol carbonate (GLC) was the only product obtained (SGLC = 100%). The results showed higher yields when using mixed oxides containing stronger basic sites. XRD analysis of the catalyst post-reaction demonstrated that the Zn-Al mixed oxides were structurally stable under the reaction conditions, with no memory effect observed.
