Kangjun Wang

CO2 hydrogenation to dimethyl ether over CuO–ZnO–Al2O3/HZSM-5 prepared by combustion route

CuO–ZnO–Al2O3/HZSM-5 catalysts were prepared and characterized by XRD, BET, N2O titration, H2-TPR, FESEM and NH3-TPD techniques. CuO–ZnO–Al2O3 catalysts were obtained by a simple and fast urea–nitrate combustion method and then mixed physically with HZSM-5 to perform one step synthesis of dimethyl ether (DME) from carbon dioxide (CO2) hydrogenation. The results showed that the grain size and copper surface areas of the catalysts were highly affected by the amount of urea in the preparation, and their catalytic performances were consequently influenced. A CO2 conversion of 30.6% and DME yield of 15% over the optimal catalyst were obtained by controlling the molar ratio of urea to metal nitrate. The work will benefit the rational design of new catalysts suitable for CO2 utilization.

Effect of Copper Nanoparticles Dispersion on Catalytic Performance of Cu/SiO2 Catalyst for Hydrogenation of Dimethyl Oxalate to Ethylene Glycol

Cu/SiO2 catalysts, for the synthesis of ethylene glycol (EG) from hydrogenation of dimethyl oxalate (DMO), were prepared by ammonia-evaporation and sol-gel methods, respectively. The structure, size of copper nanoparticles, copper dispersion, and the surface chemical states were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS) and N2 adsorption. It is found the structures and catalytic performances of the catalysts were highly affected by the preparation method. The catalyst prepared by sol-gel method had smaller average size of copper nanoparticles (about 3-4 nm), better copper dispersion, higher Cu

Size and morphology-controlled synthesis of Ni3C nanoparticles in a TEG solution and their magnetic properties

Nickel carbide nanoparticles (Ni3C NPs) were synthesized by a polyol solution refluxing route at a temperature of 300 °C for 20 min using triphenylphosphine oxide (TPPO) as the surfactant. Size and morphologies of the Ni3C NPs were controlled by adjusting the concentration of Ni(NO3)2 and TPPO. The products consisted of Ni and Ni3C could be kinetically controlled by a reaction temperature of 250–290 °C and time less than 20 min and the proportion of the Ni component was lower with longer reaction times and higher temperatures due to carbon atom insertion via a carbonaceous film that formed on the surface of the growing particles. The formation process of the Ni3C NPs was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) characterization. The saturation magnetizations of products decreased with decreasing ratio of Ni:Ni3C, which inferred that Ni3C was non-magnetic and the magnetism arose from trace Ni in the products.

Surfactant-free solvothermal method for synthesis of mesoporous nanocrystalline TiO 2 microspheres with tailored pore size

TiO2 mesoporous microspheres self-assembled from nanoparticles were synthesized by a surfactant-free solvothermal route. The TiO2 precursors were fabricated by tetrabutyl titanate, glacial acetic acid, and urea in the ethanol solution at 140°C for 20 h, and TiO2 mesoporous microspheres were obtained by a postcalcination at temperatures of 450°C for promoting TiO2 crystallization and the removal of residual organics. The phase structure, morphology, and pore nature were characterized by XRD, SEM, and nitrogen adsorption-desorptionmeasurements. The as-prepared TiO2 microspheres are in anatase phase, with 2-3 µm in diameter, and narrow pore distribution range is 3-4 nm. Theadjustments of the synthetic parameters lead to the formation of the mesoporous TiO2 microspheres with tuned pore size distributions and morphology.

Solvothermal synthesis of mesoporous TiO2 microspheres with tailored pore size and specific surface area

Mesoporous TiO2 microspheres with high specific surface area were synthesized by a template-free solvothermal method with the aid of urea. The phase structure, morphology, pore and optical properties were characterized by XRD, SEM, N2 adsorption–desorption and UV–Vis diffuse reflectance spectra. By controlling the urea concentration, size, specific surface area, pore size and optical property of the mesoporous TiO2 microspheres can be tuned.

Synthesis and catalytic performance of Ni/SiO 2 for hydrogenation of 2-methylfuran to 2-methyltetrahydrofuran

A series of Ni/SiO2 catalysts with different Ni content were prepared by sol-gel method for application in the synthesis of 2- methyltetrahydrofuran (2-MTHF) by hydrogenation of 2-methylfuran (2-MF). The catalyst structure was investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and temperature programmed reduction (TPR). It is found that structures and catalytic performance of the catalysts were highly affected by the Ni content. The catalyst with a 25% Ni content had an appropriate size of the Ni species and larger BET surface area and produced a higher 2-MF conversion with enhanced selectivity in 2-MTHF.

Phosphorus pentoxide/metal chloride mediated efficient and facile catalytic conversion of fructose into 5-hydroxymethylfurfural

Phosphorus pentoxide (P2O5)/metal chloride mixtures could significantly improve 5-HMF yield and selectivity for the catalytic conversion of fructose under mild conditions, whereas neither P2O5 nor tested metal chloride alone gave reasonable performances. A maximum 5-HMF yield of 75% with ∼85% selectivity could be achieved within 30 min at 80 °C.

The influence of composition on the functionality of hybrid CuO–ZnO–Al2O3/HZSM-5 for the synthesis of DME from CO2 hydrogenation

A series of CuO–ZnO–Al2O3/HZSM-5 hybrid catalysts with different Cu/Zn ratios and disparate Al2O3 doping were prepared and characterized by XRD, BET, H2-TPR, NH3-TPD and XPS techniques. The optimal Cu/Zn ratio is 7 : 3, and the introduction of a suitable amount of Al2O3 to form hybrid catalysts increased the BET specific area and micropore volume, facilitated the CuO dispersion, decreased the CuO crystallite size, increased the interaction between CuO and ZnO, enhanced the number of weak acid sites, altered the copper chemical state and improved the catalytic performance consequently. The highest CO2 conversion, DME selectivity and DME yield of 27.3%, 67.1% and 18.3%, respectively, were observed over the CZA7H catalyst. The suitable temperature of 260 °C and the appropriate space velocity of 1500 h−1 for one-step synthesis of dimethyl ether (DME) from carbon dioxide (CO2) hydrogenation were also investigated. The 50 h stability of the CZA7H catalyst was also tested.

Efficient Suzuki–Miyaura C-C Cross-Couplings Induced by Novel Heterodinuclear Pd-bpydc-Ln Scaffolds

An easy access to a series of previously unreported heterodinuclear Pd-Ln compounds, Pd-bpydc-La, Pd-bpydc-Ce and Pd-bpydc-Nd (bpydc = 2,2′-bipyridine-5,5′-dicarboxylate) has been developed. The Pd-Ln hybrid networks were effectively applied as catalysts in Suzuki–Miyaura C-C cross-coupling reactions of 4-bromoanisole and 4-bromobenzonitrile with phenylboronic acid, under mild conditions. A systematic investigation revealed Pd-bpydc-Nd as the most active catalyst. In all cases, reaction yields varied with the base, catalyst loading and substantially augmented with temperature (from 30 to 60 °C). Substituent effects were operative when changing from 4-bromoanisole to 4-bromobenzonitrile. The key role played by the lanthanides, aromatic substrate and base, in modulating the Pd-catalytic cycle has been highlighted. Importantly, the new catalysts proved to be stable in air and vs. functionalities and are quite efficient in Suzuki–Miyaura carbon-carbon bond formation conducted in protic solvents.