A series of Cu/TiO2‐SiO2 catalysts were prepared by a sol‐gel hydrothermal method and characterized by BET, SEM, TEM, XRD, XPS, and H2‐TPR. The catalysts were used for selective hydrogenation of furfural to furfuryl alcohol. Results show that based on the Cu/SiO2 catalyst, introducing a part of TiO2 into the carrier while keeping very large specific surface area would promote the reduction of CuO, inhibit the growth of Cu crystal particles, and improve the dispersity of Cu particles in the catalyst. The electronegativity of Cu is enhanced in the double‐loaded Cu/TiO2‐SiO2 catalyst, compared with single‐loaded Cu/SiO2 or Cu/TiO2 catalysts. The Cu/TiO2‐SiO2 catalyst containing 0.40 g/g (40 wt%) TiO2 in the carrier shows high furfural hydrogenation performance.

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Abstract:In-situ liquid-phase hydrogenation of m-chloronitrobenzene (m-CNB) based on aqueous-phase reforming (APR) of ethanol and catalytic hydrogenation was carried out over Fe-modified Pt/carbon nanotubes (CNTs) catalysts. The effects of Pt loading over CNTs and Fe modification on the catalytic performance of Pt/CNTs catalysts were studied. In-tube loading of Pt particles, compared with out-tube loading, considerably improved the catalytic activity. With in-tube loading, Fe-modified Pt/CNTs catalysts further improved the m-CNB in-situ hydrogenation performance. After Fe modification, Pt-Fe/CNTs catalysts formed, inside CNTs, a Pt-Fe alloy and iron oxides, which both improved catalytic hydrogenation performance and significantly enhanced ethanol APR hydrogen producing performance, thereby increasing the m-CNB in-situ hydrogenation reactivity.

Ni‐B amorphous alloy particles were selectively loaded inside and outside of carbon nanotubes (CNTs) to form a series of Ni‐B/CNTs amorphous alloy catalysts. The confinement effects of the CNTs on the physicochemical properties of Ni‐B/CNTs were investigated. The results show that compared with external loading, the Ni‐B active components after internal loading were subjected to the confinement effect, which better inhibited the growth and aggregation of Ni‐B particles, forming smaller‐size Ni‐B particles, and improved the thermal stability of the Ni‐B amorphous alloy. Moreover, the Ni‐B particles confined in the channels can more efficiently activate hydrogen. During the m‐chloronitrobenzene hydrogenation, the Ni‐B/CNTs with Ni‐B internal loading showed higher catalytic hydrogenation activity than that for Ni‐B external loading. High‐temperature treatment caused a decrease in the catalytic activity, but the internal loading improved the stability of the catalysts. The internal loading method could effectively reduce the loss of the active component, which contributed to improving the stability of the catalyst.

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Ni/TiO 2 catalysts with different morphologies (granular, sheet, tubular and spherical) were prepared. Hydrogen was generated from ethanol aqueous-phase reforming over Ni/TiO 2 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/TiO 2 without addition of molecular hydrogen was successful. Compared with granular, sheet and spherical Ni/TiO 2 , the nanotubular Ni/TiO 2 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/TiO 2 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-NO 2 on the active sites of the catalysts.

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