Kinetic study of the hydrogenation of citral on ir promoted Au/Tio 2 catalyst

Abstract

A kinetic study of citral hydrogenation over an Au-Ir/TiO2 catalyst was performed with the aim to understand the effect of iridium on gold in this catalytic system. Au-Ir/TiO2 catalyst was prepared by co-deposition precipitation in an atomic ratio of 3/1. The effect of citral concentration, hydrogen pressure and temperature effect were also studied. The product distribution obtained is related with the proportion of Meδ+/Me0 sites. The deactivation of the catalyst occurs in the whole studied temperature range, 363 to 403 K, being more drastic as temperature increases due to the irreversible adsorbed CO blocks principally Ir0 sites. From initial reaction rates treatment an apparent global order close to 1 was determined. A Langmuir-Hinshelwood-type kinetic model involving the surface reaction as the rate limiting step between adsorbed citral and hydrogen on active sites with different nature shows good agreement with experimental initial reaction rates.