Lanthanum-based catalysts for (bio)ethanol conversion: effect of preparation method on catalytic performance – hard templating versus hydrolysis

BACKGROUND: Lanthanum-based materials, namely La2O3 and La(OH)3, are of interest for several heterogeneous catalytic reactions because of their properties; that is, in spite of their poor resistance to CO2 and moisture, readily converting at room temperature to carbonates and oxycarbonates and requiring strong thermal treatments to revert back to their original form. RESULTS: In this study, hard template and hydrolysis synthetic procedures have been compared for the production of nanostructured La-based catalysts. The materials have been characterized by means of various techniques and tested in ethanol conversion as a probe reaction. Both preparation procedures give rise to higher surface areas than those reported for conventional synthesis and the surface properties are different, showing the formation of oxysulfate or of a complex mixture of carbonate and hydroxycarbonate. CONCLUSIONS: Lanthanum-based oxide can be efficiently prepared using different synthetic procedures that allow to obtain nanosized La-based mixed oxides. However, great attention should be paid to the preparation step, because the role of impurities markedly affects the stability and the catalytic properties of the prepared oxide. The use of the hard templating procedure allows a reduction of the amount of carbonate upon air exposure, thus stabilizing the starting oxide, by protecting the surface with the presence of lanthanum oxysulfate (La2O2SO4). © 2020 Society of Chemical Industry.