Mechanistic <i>in situ</i> investigation of heterogeneous hydrogenation over Rh/TiO<sub>2</sub> catalysts: selectivity, pairwise route and catalyst nature
Ekaterina V. Pokochueva, Dudari B. Burueva, Larisa M. Kovtunova, Andrey V. Bukhtiyarov, A. Yu. Gladky, Kirill V. Kovtunov, Igor V. Koptyug, V. I. Bukhtiyarov
Abstract
catalysts with different properties. It is shown that the nature of the precursor used for catalyst preparation is important, and that the use of a solution of rhodium acetate instead of rhodium nitrate leads to the selective formation of butenes during 1,3-butadiene hydrogenation. The use of parahydrogen in the reaction results in the enhancement of NMR signals via parahydrogen-induced polarization (PHIP) for all synthesized catalysts, and this signal enhancement increases with increasing catalyst calcination temperature. This effect is explained by the decoration of rhodium nanoparticles with titania which restricts hydrogen mobility on the surface, leading to the highest reported to date selectivity toward the pairwise hydrogen addition route of 7% for supported metal catalysts.