Abstract
Ni/TiO2 catalysts with different morphologies (granular, sheet, tubular and spherical) were prepared. Hydrogen was generated from ethanol aqueous-phase reforming over Ni/TiO2 in a water-ethanol-m-chloronitrobenzene reaction system and directly applied into m-chloronitrobenzene catalytic hydrogenation. Thereby, in-situ liquid-phase hydrogenation of m-chloronitrobenzene over Ni/TiO2 without addition of molecular hydrogen was successful. Compared with granular, sheet and spherical Ni/TiO2, the nanotubular Ni/TiO2 prepared 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 of m-chloronitrobenzene experiments showed the nanotubular Ni/TiO2 had 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 –NO2 on the active sites of the catalysts.
Highlights
Armatic haloamines are important intermediates in the synthesis of various organic compounds, such as dyes, drugs, and pesticides [1]
These techniques are limited by the shortage of fossil energy, non-renewability, high electricity consumption, and unsafety in hydrogen storage and transport, which bring about inevitable challenges for the catalytic hydrogenation techniques that depend on addition of molecular hydrogen
Ni/TNT contains more Lewis acid sites and fewer Brønsted acid sites. These results indicate the types and acidity of acid sites both differ among different morphologies
Summary
Armatic haloamines are important intermediates in the synthesis of various organic compounds, such as dyes, drugs, and pesticides [1]. Catalytic hydrogenation featured by environmental friendly, atom economy, high product purity and high yield is the most promising clean technique in the industry. The dominant method of hydrogenation reaction in catalytic hydrogenation techniques depends on the addition of molecular hydrogen. Hydrogen in industrial applications is mainly obtained from recovered byproducts of fossil energy hydrogen generation, electrolysis water hydrogen generation, and petrochemical production [11,12]. These techniques are limited by the shortage of fossil energy, non-renewability, high electricity consumption, and unsafety in hydrogen storage and transport, which bring about inevitable challenges for the catalytic hydrogenation techniques that depend on addition of molecular hydrogen
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