Junjie Yu

Guangdong Institute of Eco-environmental and Soil Sciences, Shengcheng, Guangdong, China

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Publications (6)22.25 Total impact

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    ABSTRACT: Co1.5M1.5/Al1−xTix hydrotalcite-like compounds (where M = Co, Ca and x = 0, 0.1) were synthesized by a constant-pH coprecipitation. The derived oxides from hydrotalcites upon calcination at 800 °C for 4 h were all of spinel phase without crystalline TiO2 phase being detected. Substitution of partial Al for Ti significantly enhanced NO direct decomposition activity of these catalysts. In particular, catalyst Co3.0/Al0.9Ti0.1O (CATO) showed the highest NO direct decomposition percentage, up to 86% at 300 °C with GHSV of 30 000 h−1 (800 ppm of NO and 8% O2 in N2 stream). CATO also showed the highest resistance to SO2 poisoning to NO direct decomposition, with the activity being only reduced by 16% in the presence of 64 ppm of SO2 in the mixed gas stream at 300 °C. The in-situ FT-IR spectra indicate different adsorption species over the catalysts, revealing NO surface storage/decomposition involves different adsorption reactions that determine the NO decomposition activity and resistance to SO2 poisoning.
    No preview · Article · Mar 2011 · The Journal of Physical Chemistry C
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    ABSTRACT: CoxMg3 − x /Al composite oxides (xCoMAO-800) were prepared by calcination of CoxMg3 − x/Al hydrotalcites (x = 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, respectively) at 800 °C. The materials were characterized using XRD, TG-DSC, N2 adsorption–desorption and TPR. The methane catalytic combustion over the xCoMAO-800 was assessed in a fixed bed micro-reactor. The results revealed that cobalt can be homogenously dispersed into the matrices of the hydrotalcites and determines the structure, specific surface areas and porosity of the derived xCoMAO-800 oxide catalysts. The thermal stability and homogeneity of the hydrotalcites markedly depends on the cobalt concentration in the hydrotalcites. The Co-based hydrotalcite-derived oxides exhibit good activity in the catalytic combustion of methane. The catalytic activity over the xCoMAO-800 oxides enhances with increasing x up to 1.5, but subsequently decreases dramatically as cobalt loadings are further increased. The 1.5CoMAO-800 catalyst shows the best methane combustion activity, igniting methane at 450 °C and completing methane combustion around 600 °C. The catalytic combustion activity over the xCoMAO-800 oxides are closely related to the strong Co–Mg/Al interaction within the mixed oxides according to the TG-DSC, TPR and activity characteristics.
    Full-text · Article · Jan 2010 · Fuel Processing Technology
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    ABSTRACT: Nano-Au/Co3O4 catalyst with high gold loading was found to be a good catalytic material for the elimination of trace ethylene (ppb) at ambient conditions. The gold nanoparticles dispersed on the support nano-Co3O4 surface contribute to this high activity at room temperature. The relatively rapid deactivation trend was observed under high concentrations of ethylene (1000 ppm), because coke deposits were present on the catalyst surface during the reaction process. This type of nano-gold catalytic material shows great potential as a meaningfully environmental catalyst, particularly for indoor environmental control of trace ethylene (ppb) and keeping fruits fresh during warehouse storage.
    No preview · Article · Jan 2009 · Environmental Science and Technology
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    ABSTRACT: Novel Cu1Co2/X0.2Al0.8 well-mixed oxides (where X = Fe, Mn, Ce, La) were synthesized by calcinations of corresponding hydrotalcite-like compounds at 800 °C for 4 h. Their catalytic performance for the methane combustion was investigated. The oxides and their precursors were characterized by X-ray diffraction (XRD), thermogravimetry−differential scanning calorimetry (TG-DSC), temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), and N2 adsorption/desorption techniques. The derived oxides are mainly of spinel and tenorite phase, with surface area of 10−30 m2/g, where new phase CeO2 and LaCoO3 are segregated in Ce- and La-containing oxides, respectively. The catalytic activities of the catalysts are related to the redox properties of the metal cations and the species in the surface. Incorporation of the Mn and Fe element is helpful to the reduction of the oxide catalysts, which may lead to the enhancement of the catalytic activity. Among the catalysts investigated, Cu1Co2/Mn0.2Al0.8 gives the highest catalytic activity. Light-off and complete oxidation temperature was centered at about 374 and 496 °C, respectively. The less active was Cu1Co2/Fe0.2Al0.8.The intensities of surface oxygen species over Mn- and Fe-containing oxides are much higher than other catalysts, implying the higher activity of surface oxygen for the methane combustion.
    No preview · Article · Jun 2008 · Energy & Fuels
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    ABSTRACT: Zeolite matrix FAU with large channel dissension is applied as good host for iron species and Fe-USY sample is prepared by wet ion exchange method using ferric salt as the iron source. The as-prepared Fe-USY catalyst exhibits quite good activity for N2O decomposition and a 100% conversion (to N2 and O2) can be achieved at above 748K. Besides, Fe-USY shows good durability for N2O decomposition under simulated conditions at a typical nitric acid plant, which demonstrates its potential for future application.
    No preview · Article · Apr 2008 · Catalysis Communications
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    ABSTRACT: Novel Cu-Mg/Al mixed oxides (designated as i-CMAO-800) were prepared by calcinations of Cu-Mg/Al hydrotalcites [(Cu2+ +Mg2+)/Al3+= 3] at 800 C. Their performance for the catalytic combustion of methane was investigated. The oxides and their precursors were characterized by XRD, TG-DSC, TPR and N2 adsorption/desorption techniques. The results showed that BET surface areas and the stability of the resultant oxides were greatly influenced by the copper contents in hydrotalcite precursors, bringing about difference in their activities for methane catalytic combustion. XRD results indicated that Cu was highly dispersed in hydrotalcite precursors in case of low copper contents, (Cu 40 wt%). For higher Cu contents, Cu(OH)2 was formed, and, consequently, a separate phase of CuO was detected in the oxide catalysts after calcination. As indicated by the TG-DSC results, different decomposition behaviors were observed for various hydrotalcites. Thermal calcination promoted the formation of copper aluminates and segregation of CuO from the bulk phases. TPR results showed 15CMAO-800 has the highest reduction rate, and the catalytic activities of iCMAO-800 mixed oxides depend on both the reduction rates and the amounts of copper ions in mixed oxides. The catalyst 15-CMAO-800 showed the best performance.
    Full-text · Article · Jan 2005 · Catalysis Letters

Publication Stats

137 Citations
22.25 Total Impact Points


  • 2010
    • Guangdong Institute of Eco-environmental and Soil Sciences
      Shengcheng, Guangdong, China
  • 2008-2009
    • Chinese Academy of Sciences
      • Research Center for Eco-Environmental Sciences
      Peping, Beijing, China
  • 2005
    • Chinese Research Academy of Environmental Sciences
      Peping, Beijing, China