Mechanistic in situ investigation of heterogeneous hydrogenation over Rh/TiO2 catalysts: selectivity, pairwise route, catalyst nature
Selectivity to the products formation is strongly correlated with the nature of catalyst active centers. Therefore, the selective synthesis of active sites with certain structure is a big challenge in modern catalysis. Here the synthetic procedures are adopted for the formation of 1% Rh/TiO2 catalysts with different properties. It is shown that the nature of the precursor used for catalyst preparation is important, and the use of the 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 the catalyst calcination temperature increase. This effect is explained by the decoration of rhodium nanoparticles with titania that restricts hydrogen mobility on the surface leading to the highest reported to date selectivity to the pairwise hydrogen addition route of 7% for supported metal catalysts.
- This article is part of the themed collection: Reaction mechanisms in catalysis