Lanthanum oxide behavior in La2O3-Al2O3 and La2O3-ZrO2 catalysts with application in FAME production

SALINAS, D.; ESCALONA, N.; PECCHI, G.; FIERRO, J.:
Fuel, 253 (October 2019) 400-408.

DOI:10.1016/j.fuel.2019.05.015

Abstract

La₂O₃ monolayer catalysts with 90% coverage on Al₂O₃ and 71% on ZrO₂were successfully obtained by a sol–gel method and the catalytic performance evaluated as fatty acid methyl esters (FAME) production in a canola oil transesterification reaction show differences upon the nature and extent of basic sites. The La₂O₃ monolayer does not modify strongly the textural properties of the Al₂O₃ and larger structural changes are detected on ZrO₂. For the La₂O₃-Al₂O₃ monolayer catalyst, the inter-diffusion Al³⁺/La³⁺ cation modify the nature of the acidity and increases the basicity of the Al-O-La species, whereas for the La₂O₃-ZrO₂monolayer catalyst, appearance of tetragonal ZrO₂ structure with larger basicity is detected. The effect of the nature of the support in the catalytic performance in FAME production of the La₂O₃-ZrO₂ and La₂O₃-Al₂O₃ monolayer catalyst informed as FAME % (60% at 5 h and 65 °C) for the La₂O₃-ZrO₂ is attributed to the presence of the new medium strength basic sites and the m-ZrO₂ structure, whereas the lower basicity of the La₂O₃-Al₂O₃ explain the lower fatty acid methyl esters production (45% at 5 h and 65 °C).