Hydrogenation of m-Chloronitrobenzene over Different Morphologies Ni/TiO2 without Addition of Molecular Hydrogen

Ni/TiO2catalysts with different morphologies (granular, sheet, tubular and spherical) were prepared. Hydrogen was generated from ethanol aqueous-phase reforming over Ni/TiO2in a water-ethanol-m-chloronitrobenzene reaction system and directly applied intom-chloronitrobenzene catalytic hydrogenation. Thereby, in-situ liquid-phase hydrogenation ofm-chloronitrobenzene over Ni/TiO2without addition of molecular hydrogen was successful. Compared with granular, sheet and spherical Ni/TiO2, the nanotubular Ni/TiO2prepared from one-step hydrothermal reaction had larger specific surface area, smaller and uniformly-distributed pore sizes and more Lewis acid sites. In-situ liquid-phase hydrogenation ofm-chloronitrobenzene experiments showed the nanotubular Ni/TiO2had the highest catalytic activity, which was ascribed to both catalyst morphology and acid sites. Firstly, the nanotubular structure endowed the catalysts with a nanoscale confinement effect and thereby high catalytic performance. Secondly, the Lewis acid sites not only accelerated water–gas shift reaction, enhancing the ethanol aqueous-phase reforming activity for hydrogen generation, but also promoted the adsorption and hydrogenation of –NO2on the active sites of the catalysts.Keywords:Ni/TiO2;morphology effect;in-situ hydrogenation;aqueous-phase reforming;m-chloronitrobenzene