Binary CuO/TiO2 nanocomposites as high-performance catalysts for tandem hydrogenation of nitroaromatics

Abstract

In situ hydrogenation of unsaturated compounds by released hydrogen from various hydrogen sources is a good strategy to achieve highly selective hydrogenation. In this work, inexpensive CuO/TiO 2 nanocomposites were systematically screened their performance for catalyzing dehydrogenation of ammonia borane (AB) and the tandem hydrogenation of some nitroaromatics. Those CuO/TiO 2 binary nanocomposites were found to maximize the hydrogen production from the catalytic hydrolysis of AB. Owing to a positive in-situ hydrogen activation, under mild conditions these CuO/TiO 2 nanocomposites exhibited highly excellent reactivities accompanying with better recyclability in the current one-pot hydrogenation. Notably, a selected CuO (0.5) /TiO 2(0.5) nanocomposites displayed high activity and regioselectivity (up to100% yield of aim product) as well as increased ability of inhibiting the dehalogenation reaction, especially for 4-bromonitrobenzene or 4-iodonitrobenzene (up to 71.65% yield for 4-bromoaniline or 68.02% yield of 4-iodoaniline). Moreover, that CuO (0.5) /TiO 2(0.5) nanocomposites from a co-precipitation method displayed relatively better recyclability against those two control samples obtained from a stepwise preparation process. Owing to positive in-situ hydrogen activation mechanism, CuO/TiO 2 binary nanocomposites from co-precipitation method display highly excellent reactivity, regioselectivity, and better recyclability for the tandem hydrogenation of aromatic nitro-compounds under highly mild conditions. • Binary CuO/TiO2 nanocomposites exhibited attractive reactivity toward the tandem hydrogenation of nitro-compounds. • Control experiments powerfully confirm a positive in-situ hydrogen activation benefitting the efficient tandem hydrogenation. • Distinguishable catalytic performances were observed for those catalysts coming from different preparation methods.