Jilei Xu

Selective oxidation of glycerol to lactic acid under acidic conditions using AuPd/TiO2 catalyst

The selective oxidation of glycerol was investigated using AuPd/TiO2 as the catalyst in the presence of AlCl3, and lactic acid was obtained as the predominant product. It was demonstrated that AuPd/TiO2 and AlCl3 played synergistic roles in the production of lactic acid. The possible reaction pathway was proposed, in which glycerol was first oxidized to glyceraldehyde and dihydroxyacetone, catalysed by AuPd/TiO2, followed by the formation of lactic acid, catalyzed by AlCl3.

Cyclization of o-phenylenediamines by CO2 in the presence of H2 for the synthesis of benzimidazoles

The cyclization of o-phenylenediamines by CO2 in the presence of H2 was presented to directly synthesize benzimidazoles, and a series of benzimidazoles were obtained in excellent yields using RuCl2(dppe)2 as the catalyst.

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.

Pd nanoparticles immobilized on graphite oxide modified with a base: Highly efficient catalysts for selective hydrogenation of citral

In this work, the Pd-based catalysts were designed via immobilizing Pd nanoparticles on graphite oxide (GO) modified with organic base, 1,1,3,3-tetramethylguanidine (TMG), which was used for the selective hydrogenation of citral. These catalysts were characterized by various techniques including IR, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. It was demonstrated that the Pd particles with size less than 5 nm were uniformly distributed throughout the support, and they were in the electron-deficient state due to the strong interactions with the modified support. The resultant Pd-TMG/GO catalyst displayed high efficiency for the selective hydrogenation of citral with a turnover frequency of 7100 h−1 as well as superior selectivity to citronellal of 89.6%. Moreover, the catalyst can be reused for five times without obvious activity loss, which may result from its stable structure.

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.