Hydrogenation of Citral Over IrAu/TiO2 Catalysts. Effect of the Preparation Method

Abstract

Hydrogenation of citral over Ir/TiO2 and IrAu/TiO2 catalysts was studied. Catalysts were prepared by deposition–precipitation with urea (Ir/TiO2) and sequential incorporation of the metals using a combined DPU-incipient wetness impregnation approach (IrAu/TiO2). Samples were reduced in H2 at 573 K (LT) and 773 K (HT). These materials were characterized by transmission electron microscopy (HAADF), TPR and CO adsorption followed by DRIFT. The liquid phase hydrogenation of citral was studied in a Parr type batch reactor at 363 K and a H2 pressure of 0.62 MPa. An Ir/TiO2 catalyst prepared by wet impregnation was used as reference catalyst. High selectivity to unsaturated alcohols was found, the only reaction products were geraniol and nerol for Ir/TiO2 DPU and IrAu/TiO2 catalysts. The IrAu/TiO2 (HT) catalyst showed the higher conversion levels.