Silica Modulation of Raney Nickel Catalysts for Selective Hydrogenation.

Selective hydrogenation over earth-abundant metal catalysts is challenging but particularly valuable for practical applications in heterogeneous catalysis. Herein, we demonstrate that the catalytic selectivity of the commercial Raney nickel catalyst can be greatly tuned by modulation of the nickel surface by silica. Using quinoline hydrogenation as a model, we show that the silica-modified Raney nickel catalysts exhibit good activity, excellent selectivity, and long stability, whereas the undesired overhydrogenation reactions are effectively hindered. In contrast, the pristine Raney nickel catalyst shows inferior selectivity for the targeted product. Mechanistic studies confirm a positive role of silica to facilitate the desorption of 1,2,3,4-tetrahydroquinoline from the catalyst surface, thus enhancing the product selectivity.