Activated ceria （CeO2/γ-Al2O3） prepared by impregnation was characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and hydrogen temperature-programmed reduction （TPR）. The desulfurizati...Activated ceria （CeO2/γ-Al2O3） prepared by impregnation was characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and hydrogen temperature-programmed reduction （TPR）. The desulfurization of the activated ceria was investigated by X-ray photoelectron spectroscopy （XPS）, Fourier transform infrared spectroscopy （FT-IR）, and thermogravimetric analysis （TG）. The results showed that ceria could be highly dispersed or crystallized on the surface of γ-alumina. The reduction temperatures of 0.1CeO2/γ-Al2O3, 0.45CeO2/7-A1203, and CeO2 ranged from 250℃ to 470℃, 330℃ to 550℃, and 350℃ to 550℃, respectively. The reduction peak temperature of 0.45CeO2/γ-Al2O3 was higher than that of 0.1CeO2/γ-Al2O3, which was consistent with the reduction temperature of CeO2. 02 participated in the reaction between ceria and sulfur dioxide. The desulfurization product was cerium（III） sulfate. The intensity of the hydroxyl band decreased with the formation of sulfate species.展开更多
The surface properties of sphalerite （ZnS） were theoretically investigated using first principle calculations based on the density functional theory （DFT）. DFT results indicate that both the （110） and the （220...The surface properties of sphalerite （ZnS） were theoretically investigated using first principle calculations based on the density functional theory （DFT）. DFT results indicate that both the （110） and the （220） surfaces of sphalerite undergo surface atom relaxation after geometry optimization, which results in a considerable distortion of the surface region. In the normal direction, i.e., perpendicular to the sur- face, S atoms in the first surface layer move outward from the bulk （dl）, whereas Zn atoms move toward the bulk （d2）, forming an S-enriched surface. The values of these displacements are 0.003 nm for dl and 0.021 nm for d2 on the （110） surface, and 0.002 nm for dl and 0.011 nm for d2 on the （220） surface. Such a relaxation process is visually interpreted through the qualitative analysis of molecular mechanics. X-ray photoelectron spectroscopic （XPS） analysis provides the evidence for the S-enriched surface. A polysulphide （S n^2- ） surface layer with a bind- ing energy of 163.21 eV is formed on the surface of sphalerite after its grinding under ambient atmosphere. This S-enriched surface and the S 2- surface layer have important influence on the flotation properties ofsphalerite. Keywords：展开更多
基金the finical support from the National Natural Science Foundation of China (Nos. 51264023, 51364020, and U1202271)the Program for Innovative Research Team in Universities of the Ministry of Education of China (No. IRT1250)the Yunnan Province Science and Technology Talents (No. 2014HA003)
文摘Activated ceria （CeO2/γ-Al2O3） prepared by impregnation was characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and hydrogen temperature-programmed reduction （TPR）. The desulfurization of the activated ceria was investigated by X-ray photoelectron spectroscopy （XPS）, Fourier transform infrared spectroscopy （FT-IR）, and thermogravimetric analysis （TG）. The results showed that ceria could be highly dispersed or crystallized on the surface of γ-alumina. The reduction temperatures of 0.1CeO2/γ-Al2O3, 0.45CeO2/7-A1203, and CeO2 ranged from 250℃ to 470℃, 330℃ to 550℃, and 350℃ to 550℃, respectively. The reduction peak temperature of 0.45CeO2/γ-Al2O3 was higher than that of 0.1CeO2/γ-Al2O3, which was consistent with the reduction temperature of CeO2. 02 participated in the reaction between ceria and sulfur dioxide. The desulfurization product was cerium（III） sulfate. The intensity of the hydroxyl band decreased with the formation of sulfate species.
基金supported by the Key Program of the National Natural Science Foundation of China (No.u0837602)the Analysis Testing Foundation of Kunming University of Science and Technology (No.2010-303)
文摘The surface properties of sphalerite （ZnS） were theoretically investigated using first principle calculations based on the density functional theory （DFT）. DFT results indicate that both the （110） and the （220） surfaces of sphalerite undergo surface atom relaxation after geometry optimization, which results in a considerable distortion of the surface region. In the normal direction, i.e., perpendicular to the sur- face, S atoms in the first surface layer move outward from the bulk （dl）, whereas Zn atoms move toward the bulk （d2）, forming an S-enriched surface. The values of these displacements are 0.003 nm for dl and 0.021 nm for d2 on the （110） surface, and 0.002 nm for dl and 0.011 nm for d2 on the （220） surface. Such a relaxation process is visually interpreted through the qualitative analysis of molecular mechanics. X-ray photoelectron spectroscopic （XPS） analysis provides the evidence for the S-enriched surface. A polysulphide （S n^2- ） surface layer with a bind- ing energy of 163.21 eV is formed on the surface of sphalerite after its grinding under ambient atmosphere. This S-enriched surface and the S 2- surface layer have important influence on the flotation properties ofsphalerite. Keywords：
