Huanjun Xu

Au catalyzed synthesis of benzimidazoles from 2-nitroanilines and CO2/H2

The gold-catalyzed synthesis of benzimidazoles from 2-nitroanilines and CO2 in the presence of H2 was reported, and a series of benzimidazoles were obtained under relatively mild conditions. Several supported Au catalysts including Au/TiO2, Au/Al2O3, Au/ZnO, Au/polyurea and Au/hydrotalcite were examined for the synthesis of benzimidazole from the reaction of 2-nitroaniline with CO2 and H2, among which Au/TiO2 displayed the best performance. The reaction mechanism was investigated, and it was found that the production of benzimidazole underwent the formation of o-phenylenediamine via the hydrogenation of 2-nitroaniline, followed by the cyclization of o-phenylenediamine with CO2 and H2. This work provides a CO2-involved route for the synthesis of benzimidazoles, which may widen the applications of CO2 in the chemical synthesis.

Ionic liquid modified montmorillonite-supported Ru nanoparticles: highly efficient heterogeneous catalysts for the hydrodeoxygenation of phenolic compounds to cycloalkanes

The Ru/MMT@IL-SO3H catalyst was prepared by immobilizing Ru nanoparticles onto montmorillonite (MMT) with the assistance of an acidic ionic liquid (1-sulfobutyl-3-methylimidazolium hydrosulfate, IL-SO3H). Transmission electron microscopy examination indicated that the loaded Ru species were distributed uniformly on the MMT support with a particle size of about 1.3 nm, which existed mainly in the form of a metallic state as confirmed by X-ray photoelectron spectroscopy analysis. X-Ray diffraction analysis indicated that the interlayer distance of MMT was increased due to the impregnation of IL-SO3H. The activity of Ru/MMT@IL-SO3H for hydrodeoxygenation (HDO) of various phenolic compounds was investigated. It was demonstrated that the as-prepared catalyst served as a bifunctional catalyst and displayed high efficiency for HDO reactions of a series of phenolic compounds to cycloalkanes.

Heteropolyanion-based ionic liquids catalysed conversion of cellulose into formic acid without any additives

Heteropolyanion-based ionic liquids with –SO3H functionalized cations and PMo11VO404− anions were synthesized and applied in the conversion of cellulose into formic acid (FA). It was demonstrated that the as-prepared ILs showed enhanced activity for catalysing cellulose conversion to FA in the presence of oxygen in water compared to H4PMo11VO40. A high FA yield over 50% accompanied by a FA concentration of ∼10% in reaction solution was obtained at 180 °C and in an oxygen pressure of 1.0 MPa. The possible pathway of FA production from cellulose was investigated. It was indicated that the resulting ILs served as bifunctional catalysts with cations catalysing the cellulose hydrolysis to glucose and anions catalysing glucose oxidation to FA. These ILs may find more applications in cellulose conversion.

Ti3+ self-doped TiOx@anatase core–shell structure with enhanced visible light photocatalytic activity

Ti3+ self-doped TiOx@anatase core–shell structures were prepared via hydrolysis of Ti2(SO4)3 around TiO particles, followed by post-calcination at temperatures from 723 to 823 K. The as-prepared TiOx@anatase was examined by means of transmission electronic microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. It was demonstrated that the samples displayed core–shell structures with the shell in the anatase form and the core in the anatase and rutile phases, and a large number of Ti3+ ions were present. Electron paramagnetic resonance analysis indicated that the Ti3+ ions were located throughout the whole sample, including the shell, the core and the interface between the core and the shell. The as-prepared TiOx@anatase core–shell catalysts can absorb visible light and showed good activity for catalyzing the degradation of Rhodamine B under visible light irradiation. In particular, the TiOx@anatase obtained at 773 K showed the best performance, due to the high concentration of well-dispersed Ti3+ ions in the sample.

Polyurea-supported metal nanocatalysts: synthesis, characterization and application in selective hydrogenation of o-chloronitrobenzene.

Polyurea (PU) spheres with size of 2-10 μm were derived through the polymerization of CO2 with 1,4-butanediamine, and characterized by FTIR spectroscopy, scanning electron microscopy and TG analysis. It was demonstrated that the PU spheres displayed flower-like morphology with the betel thickness around 30 nm, and they had high thermal stability. The resultant PU spheres were used to immobilize metal particles, and a series of PU-supported metal nanocatalysts including Pt/PU, Au/PU, Pd/PU were prepared via just mixing the metal precursors with the PU spheres in water, followed by the reduction of metal ions by NaBH4. Transmission electron microscopy examination indicated that the metal nanoparticles were distributed uniformly on the surface of the PU spheres with mean particle size less than 3.0 nm, and the Pt particles existed mainly in the form of metallic state as confirmed by the X-ray photoelectron spectroscopy analysis. The performance of the Pt/PU catalyst was tested in the catalytic hydrogenation of o-chloronitrobenzene, and a high selectivity of 99.5% toward o-chloroaniline at complete conversion of o-chloronitrobenzene was obtained at room temperature.

Cu-catalyzed aerobic oxygenation of 2-phenoxyacetophenones to alkyloxy acetophenones

Cu-catalyzed aerobic oxygenation of 2-phenoxyacetophenones in the presence of alcohols was reported, and the corresponding alkyl benzoates, alkyloxy acetophenones and phenols were produced in high yields.

Hydrogen‐Bonding‐Mediated Synthesis of Atomically Thin TiO2 Films with Exposed (001) Facets and Applications in Fast Lithium Insertion/Extraction

Ultrathin two-dimensional (2D) crystalline materials show high specific surface area (SA) of high energy (HE) facets, imparting a significant improvement in their performances. Herein we report a novel route to synthesize TiO2 nanofilms (NFs) with atomic thickness (<2.0 nm) through a solvothermal reaction mediated by the hydrogen-bonding networks constructed by hydroquinone (HQ). The resultant TiO2 NFs have nearly 100 % exposed (001) facets and give an extremely high SA up to 487 m(2)  g(-1) . The synergistic effect of HQ and choline chloride plays a vital role in the formation of TiO2 NFs and in the exposure of HE (001) facets. Because of its ultrathin feature and exposed (001) facet, the N2 -annealled TiO2 NFs showed fast kinetics of lithium insertion/extraction, demonstrating foreseeable applications in the energy storage.