The development of Ni-based catalyst with simultaneous outstanding catalytic performance and low cost and the exploration of nitrobenzene hydrogenation mechanism are in urgent need but still remain a severe challenge. Herein, a nickel phyllosilicate (Ni@Si) catalyst in which Ni species are stabilized by SiO x ligands is successfully prepared and applied in nitrobenzene hydrogenation to obtain aniline, exhibiting excellent catalytic performance (∼97.6% yield). A combination study reveals that the Ni 0 and Ni 2+ species cooperatively catalyze the reaction and govern the catalytic performance of the rate-determining step, namely N O group reduction. Specifically, Ni 0 species facilitates activation and dissociation of H 2 , while Ni 2+ species accounts for the adsorption of N O group via the lone electron pairs in oxygen. This work would pave the way to the rational design of efficient Ni-based catalysts and deepen the fundamental understanding for nitrobenzene hydrogenation.
Jie Wang,Zhenyu Ge,Linjuan Pei,Peng Kong,Ruiyi Wang,Pengqi Zhu,Meixian Liu,Xianmo Gu,Zhanfeng Zheng
A high aniline yield was achieved by the combination of near-UV light as the driving force of nitrobenzene reduction and a ZnNb2O6 surface as the product-selective controller. Here, a ZnNb2O6 fibre, having a wide band gap and both acidic and basic sites, was exploited by a novel ion-exchange method to study the effect of the surface acidity and basicity of catalysts on the product selectivity under near-UV light irradiation without the interference of photo-generated carriers. ZnNb2O6 showed the highest aniline yield compared to Nb2O5 and ZnO. The results of experimental and theoretical calculations confirmed that the acidic sites on the surface of ZnNb2O6 promoted the breakage of the N–O bond in the intermediate phenylhydroxylamine while the basic sites were attached to the dissociated hydrogen of isopropyl alcohol, resulting in high aniline selectivity.
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