The 1.5% Au/Fe2O3 catalysts prepared by an inverse co-precipitation method calcined at different temperatures was characterized by XRD, XPS, TEM, BET, and tested by CO selective oxidation in H2-rich gas. The results s...The 1.5% Au/Fe2O3 catalysts prepared by an inverse co-precipitation method calcined at different temperatures was characterized by XRD, XPS, TEM, BET, and tested by CO selective oxidation in H2-rich gas. The results show that the chemical composition and activity of the catalysts are greatly changed with the variation of calcination temperature. The catalyst Au/Fe2O3 calcined at 200℃, highly dispersed particles with the partially oxidized gold species on the support with the mean diameter of 3nm～5nm, displayes the best activity and selectivity of CO selective oxidation. However, the catalytic activity of Au/Fe2O3 decreases drastically with increasing calcination temperature due to the aggregation of metallic gold and bigger particle sizes. It is found that the catalytic behavior is related to the gold particle size but the nature of the support. On the basis of characterization data, in addition to the particle size of metallic gold, the oxidation states of gold are proven to be important for CO selective oxidation in H2-rich gas.展开更多
Iron polymeric hydroxygroups pillared clays(Fe-PILC) were prepared by Na+-montmorillonite with iron pillaring agent. 2.01Au/Fe-PILC catalyst was obtained by deposited-precipitation(DP) method. 2.52Au/Fe-oxide catalyst...Iron polymeric hydroxygroups pillared clays(Fe-PILC) were prepared by Na+-montmorillonite with iron pillaring agent. 2.01Au/Fe-PILC catalyst was obtained by deposited-precipitation(DP) method. 2.52Au/Fe-oxide catalyst was prepared by co-precipitation method. The catalytic activity of these catalysts was measured by catalytic combustion of formaldehyde. The catalyst of 2.01Au/Fe-PILC exhibits the high catalytic activity. The catalytic combustion reaction of formaldehyde proceeds at considerable rates at 20 ℃ and complete burn-off of formaldehyde is achieved at 120 ℃. The structure of catalysts,the valence state of gold and the size of gold particles were investigated by means of X-ray powder diffractometry,X-ray photoelectron spectroscopy and transmission electron microscopy. The results show that gold atoms with partially positive charge exist in the catalyst and play an important role in the catalytic activity. In addition,nano-sized,well-dispersed gold particles and good adsorption properties of support are necessary to obtain high activity Au catalysts for catalytic combustion of formaldehyde.展开更多
Abstract: Magnesioferrite, a rare metasomatic mineral, was discovered for the first time in China from the Qinlou Au (Fe, Cu) magnesian skarn deposit, Sanpu, Huaibei, Auhui Province, and the Mulonggou Fe (Mo, Cu) magn...Abstract: Magnesioferrite, a rare metasomatic mineral, was discovered for the first time in China from the Qinlou Au (Fe, Cu) magnesian skarn deposit, Sanpu, Huaibei, Auhui Province, and the Mulonggou Fe (Mo, Cu) magnesian skarn deposit, Luonan County, Shaanxi Province. In this paper, the geological setting, mineral associations, chemical composition, some physical properties, X-ray powder diffraction data and infrared spectroscopy of magnesioferrite and magnesiomagnetite are discussed. Magnesioferrite contains 17.66%–13.48% of MgO. Its main associated minerals are clinohumite, chondrodite, serpentine, calcite and magnesiomagnetite. The density of magnesioferrite is 4.537–4.720, reflectances in percent are: 17.8–18.1, hardness is 838–900 kg/mm2, and the cell parameter ao = 8.371–8.379 ?. A systematic study of the magnesioferrite-magnesiomagnetite-magnetite series suggests that along with the increase of magnesioferrite molecules in the mineral, the density, reflectances and cell parameters decrease correspondingly, the hardness heightens, and the infrared absorption spectral band becomes wider. The authors consider that magnesioferrite is a product of contact metasomatism between hypabyssal intermediate-acid intrusions and dolomitic marble. It was formed in shallow exocontact zones under relatively oxidized conditions.展开更多
文摘The 1.5% Au/Fe2O3 catalysts prepared by an inverse co-precipitation method calcined at different temperatures was characterized by XRD, XPS, TEM, BET, and tested by CO selective oxidation in H2-rich gas. The results show that the chemical composition and activity of the catalysts are greatly changed with the variation of calcination temperature. The catalyst Au/Fe2O3 calcined at 200℃, highly dispersed particles with the partially oxidized gold species on the support with the mean diameter of 3nm～5nm, displayes the best activity and selectivity of CO selective oxidation. However, the catalytic activity of Au/Fe2O3 decreases drastically with increasing calcination temperature due to the aggregation of metallic gold and bigger particle sizes. It is found that the catalytic behavior is related to the gold particle size but the nature of the support. On the basis of characterization data, in addition to the particle size of metallic gold, the oxidation states of gold are proven to be important for CO selective oxidation in H2-rich gas.
基金Projects (20263001, 20601012) supported by the National Natural Science Foundation of ChinaProject (ND412) supported by Inner Mongolia University Youth Foundation, China
文摘Iron polymeric hydroxygroups pillared clays(Fe-PILC) were prepared by Na+-montmorillonite with iron pillaring agent. 2.01Au/Fe-PILC catalyst was obtained by deposited-precipitation(DP) method. 2.52Au/Fe-oxide catalyst was prepared by co-precipitation method. The catalytic activity of these catalysts was measured by catalytic combustion of formaldehyde. The catalyst of 2.01Au/Fe-PILC exhibits the high catalytic activity. The catalytic combustion reaction of formaldehyde proceeds at considerable rates at 20 ℃ and complete burn-off of formaldehyde is achieved at 120 ℃. The structure of catalysts,the valence state of gold and the size of gold particles were investigated by means of X-ray powder diffractometry,X-ray photoelectron spectroscopy and transmission electron microscopy. The results show that gold atoms with partially positive charge exist in the catalyst and play an important role in the catalytic activity. In addition,nano-sized,well-dispersed gold particles and good adsorption properties of support are necessary to obtain high activity Au catalysts for catalytic combustion of formaldehyde.
基金This research was supported by the National Natural Science Foundation of China grant 49573184.
文摘Abstract: Magnesioferrite, a rare metasomatic mineral, was discovered for the first time in China from the Qinlou Au (Fe, Cu) magnesian skarn deposit, Sanpu, Huaibei, Auhui Province, and the Mulonggou Fe (Mo, Cu) magnesian skarn deposit, Luonan County, Shaanxi Province. In this paper, the geological setting, mineral associations, chemical composition, some physical properties, X-ray powder diffraction data and infrared spectroscopy of magnesioferrite and magnesiomagnetite are discussed. Magnesioferrite contains 17.66%–13.48% of MgO. Its main associated minerals are clinohumite, chondrodite, serpentine, calcite and magnesiomagnetite. The density of magnesioferrite is 4.537–4.720, reflectances in percent are: 17.8–18.1, hardness is 838–900 kg/mm2, and the cell parameter ao = 8.371–8.379 ?. A systematic study of the magnesioferrite-magnesiomagnetite-magnetite series suggests that along with the increase of magnesioferrite molecules in the mineral, the density, reflectances and cell parameters decrease correspondingly, the hardness heightens, and the infrared absorption spectral band becomes wider. The authors consider that magnesioferrite is a product of contact metasomatism between hypabyssal intermediate-acid intrusions and dolomitic marble. It was formed in shallow exocontact zones under relatively oxidized conditions.
