ZnO–Al2O3–La2O3 layered double hydroxides as catalysts precursors for the esterification of oleic acid fatty grass at low temperature

ZnO–Al2O3–La2O3 layered double hydroxides were synthesized by the coprecipitation method and calcined at 400 °C in order to obtain the corresponding mixed oxides. XRD patterns showed lamellar type materials in fresh solids (dried) while for calcined samples the characteristic mixed oxides and zincite peaks were observed. After calcination, high specific surface areas (180–130 m2/g) were obtained in the mixed oxides. TPD-CO2 denotes a shift in the CO2 desorption peak to highest temperature in the samples containing La3+. In the oleic acid esterification with methanol, under soft reaction conditions (100 °C and 6 atm), ZnAlLa mixed oxides reached conversions of 75% to the ester after 15 min and higher than 88% after 1 h of reaction.

Graphical abstractHigh activity for the esterification of oleic acid was obtained under soft conditions 100 °C using ZnAlLa mixed oxides synthesized from the calcinations of LDH structures.Figure optionsDownload full-size imageDownload high-quality image (176 K)Download as PowerPoint slideHighlights► High basicity strength was found in ZnO–Al2O3–La2O3 mixed oxides. ► ZnO–Al2O3–La2O3 mixed oxides was very active for oleic acid esterification. ► ZnO–Al2O3–La2O3 mixed oxides reaches up to 88% of oleic acid esterification.