Hollow silica spheres possessing excellent mechanical properties were successfully prepared through a layer-by-layer process using uniform polystyrene （PS） latex fabricated by dispersion polymerization as template. ...Hollow silica spheres possessing excellent mechanical properties were successfully prepared through a layer-by-layer process using uniform polystyrene （PS） latex fabricated by dispersion polymerization as template. The formation of hollow SiO2 micro-spheres, structures and properties were observed in detail by zeta potential, SEM, TEM, FTIR, TGA and nitrogen sorption porosimetry. The results indicated that the hollow spheres were uniform with particle diameter of 1.6 μm and shell thickness of 150 nm. The surface area was 511 m2/g and the pore diameter was 8.36 nm. A new stationary phase for HPLC was obtained by using C18-derivatized hollow SiO2 micro-spheres as packing materials and the chromatographic properties were evaluated for the separation of some regular small molecules. The packed column showed low column pressure, high values of efficiency （up to about 43 000 plates/m） and appropriate asymmetry factors.展开更多
Copper-cerium-zirconium catalysts loaded on Ti02 prepared by a wet impregnation method were investigated for NHz-selective catalytic reduction （SCR） of NOx. The reaction mechanism was proposed on the basis of result...Copper-cerium-zirconium catalysts loaded on Ti02 prepared by a wet impregnation method were investigated for NHz-selective catalytic reduction （SCR） of NOx. The reaction mechanism was proposed on the basis of results from in situ diffuse reflectance infrared transform spectroscopy （DRIFT）. When NH3 is introduced, ammonia bonded to Lewis acid sites is more stable over CuCe0.25Zr0.75/TiO2 at high temperature, while Brensted acid sites are more important than Lewis acid sites at low temperature. For the NH3＋NO＋O2 co-adsorption, NH3 species occupy most of activity sites on CuCe0.25Zr0.75/TiO2 catalyst, and mainly exist in the forms of NH4＋ （at low temperature） and NH3 coordinated （at high temperature）, playing a crucial role in the NHz-SCR process. Two different reaction routes, the L-H mechanism at low temperature （〈 200℃） and the E-R mechanism at high temperature （〉200℃）, are presented for the SCR reaction over C uCe0.25Zr0.75/TiO2 catalyst.展开更多
基金This project was supported by the National Natural Science Foundation of China （Grant No. 51406109）.
文摘Hollow silica spheres possessing excellent mechanical properties were successfully prepared through a layer-by-layer process using uniform polystyrene （PS） latex fabricated by dispersion polymerization as template. The formation of hollow SiO2 micro-spheres, structures and properties were observed in detail by zeta potential, SEM, TEM, FTIR, TGA and nitrogen sorption porosimetry. The results indicated that the hollow spheres were uniform with particle diameter of 1.6 μm and shell thickness of 150 nm. The surface area was 511 m2/g and the pore diameter was 8.36 nm. A new stationary phase for HPLC was obtained by using C18-derivatized hollow SiO2 micro-spheres as packing materials and the chromatographic properties were evaluated for the separation of some regular small molecules. The packed column showed low column pressure, high values of efficiency （up to about 43 000 plates/m） and appropriate asymmetry factors.
文摘Copper-cerium-zirconium catalysts loaded on Ti02 prepared by a wet impregnation method were investigated for NHz-selective catalytic reduction （SCR） of NOx. The reaction mechanism was proposed on the basis of results from in situ diffuse reflectance infrared transform spectroscopy （DRIFT）. When NH3 is introduced, ammonia bonded to Lewis acid sites is more stable over CuCe0.25Zr0.75/TiO2 at high temperature, while Brensted acid sites are more important than Lewis acid sites at low temperature. For the NH3＋NO＋O2 co-adsorption, NH3 species occupy most of activity sites on CuCe0.25Zr0.75/TiO2 catalyst, and mainly exist in the forms of NH4＋ （at low temperature） and NH3 coordinated （at high temperature）, playing a crucial role in the NHz-SCR process. Two different reaction routes, the L-H mechanism at low temperature （〈 200℃） and the E-R mechanism at high temperature （〉200℃）, are presented for the SCR reaction over C uCe0.25Zr0.75/TiO2 catalyst.
