Citral hydrogenation over novel niobia and titania supported Au, Ir-Au and Ir catalysts

摘要

The hydrogenation of citral over Au, Ir-Au and Ir catalysts prepared from colloids using as supports TiO2 and Nb2O5 has been studied. The samples were characterized by N2 adsorption at 77 K, transmission electron microscopy and temperature programmed reduction. The reactivity and selectivity differences between the prepared catalysts have been explained considering that the deposition of colloids prepared in basic media at high pressures of hydrogen occurs preferentially as iridium oxide or gold complexes, similarly to classical methods of preparation (wetness impregnation and deposition-precipitation). In this sense, the catalytic behavior of supported colloids is similar to these methods without the reduction process. This was corroborated when the solids were reduced at 773 K, which leads to catalysts active and highly selective to the hydrogenation of the carbonyl bond.