The activities of CeO2 nanocubes calcined at different temperatures were tested for catalytic oxidation of o-xylene.Using CeO2 nanocubes as catalysts,complete catalytic oxidation of o-xylene was achieved below 210°C.The CeO2 nanomaterials were characterized by means of BET,X-ray diffraction(XRD),transmission electron microscopy(TEM),and high-resolution transmission electron microscopy(HRTEM).From the TEM images,all CeO2 nanocubes displayed cubic morphology irrespective of calcination temperature.The HRTEM images revealed that these nanocubes were enclosed by reactive {001} planes,which may contribute to the intrinsically catalytic property of o-xylene oxidation.The higher activity of CeO2 nanocubes calcined at 550°C than those calcined at above 550°C was attributed to their smaller crystallite size and larger surface area.The influences of reaction conditions were also studied,which found that a higher reaction temperature was necessary for complete catalytic oxidation of o-xylene at higher weight hourly space velocity(WHSV) and o-xylene concentration.
CuO-CeO2 catalysts were prepared by a urea precipitation method for the oxidative steam reforming of ethanol at low-temperature.The catalytic performance was evaluated and the catalysts were characterized by inductively coupled plasma atomic emission spectroscopy,X-ray diffraction,temperature-programmed reduction,field emission scanning electron microscopy and thermo-gravimetric analysis.Over CuOCeO2 catalysts,H2 with low CO content was produced in the whole tested temperature range of 250–450 C.The non-noble metal catalyst 20CuCe showed higher H2production rate than 1%Rh/CeO2 catalyst at 300–400 C and the advantage was more obvious after 20 h testing at400 C.These results further confirmed that CuO-CeO2 catalysts may be suitable candidates for low temperature hydrogen production from ethanol.
