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Zha F.,Northwest Normal University | Tian H.,Northwest Normal University | Yan J.,Northwest Normal University | Chang Y.,Northwest Normal University | Chang Y.,Key Laboratory of Polymer Material of Gansu Province
Applied Surface Science | Year: 2013

The mixed acid of H2SO4/HNO3-pretreated multi-walled carbon nanotubes was employed as supports and ultrasound-assisted co-precipitation method was designed to prepare multi-walled carbon nanotubes supported CuO-ZnO-Al2O3/HZSM-5 catalyst. The catalyst was characterized by means of X-ray diffraction spectrum (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), thermal analysis (TG) and Brunauer-Emmett-Teller (BET). The catalyst activity for the preparation of dimethyl ether from hydrogenation of CO2 was investigated in a fixed-bed reactor, which showed that multi-walled carbon nanotubes could promote the catalyst activity of CuO-ZnO-Al2O3/HZSM-5. Under the reaction conditions of temperature at 262 C, pressure at 3.0 MPa, H 2/CO2 = 3 (volume ratio) and space velocity (SV) = 1800 mL gcat -1 h-1, the conversion per pass of carbon dioxide was 46.2%, with the dimethyl ether yield and selectivity of 20.9% and 45.2%. © 2013 Elsevier B.V. All rights reserved. Source


Zha F.,Northwest Normal University | Huang W.,Northwest Normal University | Wang J.,Northwest Normal University | Chang Y.,Northwest Normal University | And 3 more authors.
Chemical Engineering Journal | Year: 2013

Nanocomposed aluminum oxide modified palygorskite was prepared and some of methods such as X-ray diffraction (XRD), N2 adsorption technique surface area and pore size, and scanning electron microscopic (SEM) with energy dispersive X-ray spectroscopy (EDS) were used to characterize analysis. Compared with aluminum oxide particles, acid activated palygorskite and natural palygorskite clay, aluminum oxide modified palygorskite shows better arsenate adsorption capacity. The effects of adsorption time, temperature, acidity and co-existing anions such as fluorine, bromide, chloride, sulfate, phosphate, nitrite and nitrate on the removal of arsenate from water were investigated. The adsorption thermodynamics was conducted, which shows that the adsorption of arsenate on aluminum oxide modified palygorskite can be better simulated by Redlich-Peterson model and the adsorption is an endothermic and spontaneous process. Kinetics studies show the adsorption is a pseudo-second-order process, which is controlled by surface diffusion at the beginning and then controlled by intraparticle diffusion. © 2012 Elsevier B.V. Source


Yang F.,Northwest Normal University | Sun S.,Northwest Normal University | Chen X.,Northwest Normal University | Chang Y.,Northwest Normal University | And 6 more authors.
Applied Clay Science | Year: 2016

Highly effective clay adsorbents of Mg-Al layered double hydroxides modified palygorskite were prepared from the mixture of metal salts, urea and palygorskite by the in situ hydrothermal crystallization method. The obtained adsorbents were characterized by FT-IR, TG, XRD and SEM/EDS. The adsorption performances were evaluated for the removal of Pb2+, Cu2+ and Ni2+ in the aqueous solution. The adsorption capacities of the three metal cations at variable pH, contact times and metal concentrations were determined by atomic adsorption spectrometry. The adsorption capacities of the three metal cations on Mg-Al layered double hydroxides modified palygorskite were higher than those of palygorskite and Mg-Al layered double hydroxides at the initial metal ion concentration of 100mg/L and initial pH of 5.0. The experimental data showed a good compliance with the Langmuir isotherm and the pseudo-second-order kinetic model. Taking advantage of the combined benefits of palygorskite and Mg-Al layered double hydroxides, the as-prepared adsorbents exhibit selective and fast rating adsorption for Pb2+. © 2016 Elsevier B.V. Source


Zha F.,Northwest Normal University | Zha F.,Key Laboratory of Polymer Material of Gansu Province | Ding J.,Northwest Normal University | Chang Y.,Northwest Normal University | And 3 more authors.
Industrial and Engineering Chemistry Research | Year: 2012

The direct synthesis of a millimeter-sized core-shell-like catalyst that can be used in the hydrogenation of carbon dioxide to dimethyl ether was achieved by in situ hydrothermal synthesis. The capsule catalyst exhibited a special core-shell-like structure of a coprecipitated CuO/ZnO/Al 2O 3 core enwrapped by one layer of metal-doped amorphous silica-alumina (ASA) membrane and was characterized by XRD, SEM, and thermal analysis. The effects of metal oxide cores and membranes prepared with different precipitants, structure-directing templates, and hydrothermal synthesis conditions, as well as temperatures and pressures, on the catalytic activity of the capsule catalyst for the hydrogenation of CO 2 to dimethyl ether were investigated. Under reaction conditions of a pressure of 3.0 MPa, a space velocity (SV) of 1800 mL·g cat -1·h -1, a CO 2/H 2 volume ratio of 1:3, and a temperature of 266 °C, the capsule catalysts with cores coprecipitated by urea using n-butylamine as the templating agent to enwrap the amorphous silica-alumina membranes had excellent catalytic properties for dimethyl ether synthesis, and the conversion of CO 2 reached 47.1%, with a dimethyl ether yield and selectivity of 19.9% and 42.4%, respectively. © 2011 American Chemical Society. Source


Yang F.,Northwest Normal University | He Y.,Northwest Normal University | Sun S.,Northwest Normal University | Chang Y.,Northwest Normal University | And 8 more authors.
Journal of Applied Polymer Science | Year: 2016

The walnut shell supported nanoscale zero-valent iron (walnut-nZVI) was prepared from sodium borohydride, iron(II) chloride tetrahydrate, and walnut shell by liquid phase chemical reduction and characterized by FTIR, TEM, and XRD. The composites were tested as adsorbent for the removal of Cu(II) or Ni(II) ions. The equilibrium data were analyzed by the Langmuir, Freundlich, Dubinin-Radushkevich, which revealed that Langmuir isotherm was more suitable for describing Cu(II) and Ni(II) ions adsorption than the other two isotherm models. The results indicated that the maximum adsorption capacity was higher than some other modified biomass waste adsorbents under the proposed conditions, were 458.7, 327.9 mg g-1 for Cu(II) or Ni(II). The adsorption kinetics data indicated that the adsorption fitted well with the pseudo-second-order kinetic model. © 2015 Wiley Periodicals, Inc. Source

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