In-situ characterization of the thermal treatment of Zn-Al hydrotalcites with respect to the formation of Zn/Al mixed oxide active in aldol condensation of furfural

Manuscript firstly describes the transformation of Zn-Al hydrotalcites into the appropriate Zn-Al mixed oxides during their thermal treatment up to 1000 degrees C. In detail, the structure, composition, morphology and growth of ZnO and ZnAl2O4 phases are analysed by using of TGA, in-situ XRD and in-situ diffuse reflectance UV-vis spectroscopy. Secondly, composition (XRF), structure (XRD), texture (N-2 adsorption) and acid-base properties (TPD-NH3, TPD-CO2) of Zn-Al mixed oxides prepared by thermal treatment of Zn-Al hydrotalcites at 400 degrees C are described. Zn-Al mixed oxides are studied with respect to their utilization in the aldol condensation of furfural with acetone. Manuscript defines the region of the ZnO phase formation and their role on textural, structural, acid-base and catalytic properties of Zn-Al mixed oxides formed by thermal treatment of hydrotalcites. High values of the conversion of furfural well correlated with the low values of ZnO crystallite size and high values of the specific surface area. The contribution of acid-base properties could not be discussed, as studied mixed oxides exhibited approximately the same amount and strength of basic sites.