NATURE AND EFFECT OF THE SUPPORT IN THE SELECTIVE HYDROGENATION OF CITRAL OVER SILICA-ZIRCONIA AND SILICA-TITANIA PLATINUM CATALYST

The synthesis of fine chemicals, particularly flavors and fragrances involves hydrogenation of unsaturated aldehydes to unsaturated alcohols. Catalytic hydrogenation of citral over a series of platinum catalysts supported on SiO2 and mixed oxides of SiO2-ZrO2 and SiO2-TiO2 was studied. The aim was to increase the selectivity towards the unsaturated alcohol (citronellol). The oxides used as catalytic supports were synthesized by the solgel synthesis at a temperature of 353 K. The metal loading (1 wt% Pt) remained constant while the effect of adding different compositions of ZrO2 or TiO2 in SiO2 matrix was analyzed. The catalysts were characterized by hydrogen chemisorption, nitrogen adsorption at 77K and TEM. By using Pt catalysts supported on mixed oxides of SiO2-ZrO2 and SiO2-TiO2 with a high weight percentage of SiO2, citronellal and citronellol were produced with a total conversion of the citral molecule.