Based on the γ-Al2O3 support with large-size pores, impregnation-deposition method was adopted to prepare the nano CeO_2/γ-Al2O3 composite supports. The results of XRD showed that there was no CeO_2-Al2O3 mixture or...Based on the γ-Al2O3 support with large-size pores, impregnation-deposition method was adopted to prepare the nano CeO_2/γ-Al2O3 composite supports. The results of XRD showed that there was no CeO_2-Al2O3 mixture or solid solution, indicating that CeO_2 was only loaded on the surface of Al2O3. The CeO_2/γ-Al2O3 composite support had larger specific surface area (170 m2·g-1), while for the non-loaded nanosized CeO_2, the specific surface area was small(～50 m2·g-1). The influence of impregnation and drying methods on the surface properties, thermal stability and crystal structure of composite supports was characterized by XRD, DTA and BET. The CeO_2/γ-Al2O3 composite support prepared by vacuum impregnation and microwave drying was better than that prepared by conventional impregnation and drying.展开更多
TWC-equipped exhausts are widely used in gasoline-fueled vehicles to meet stringent emission regulations. The main components in TWCs are precious metals such as palladium (Pd), platinum (Pt), and rhodium (Rh) as the ...TWC-equipped exhausts are widely used in gasoline-fueled vehicles to meet stringent emission regulations. The main components in TWCs are precious metals such as palladium (Pd), platinum (Pt), and rhodium (Rh) as the active component, and inorganic oxides such as γ-alumina (Al 2 O 3 ), ceria (CeO 2 ), zirconia (ZrO 2 ) and ceria-zirconia (CeO 2-ZrO 2 ) are used as the support. Interaction of precious metals and support plays an important role in the thermal stability and catalytic performance of TWCs. The support can improve the dispersion of precious metals and suppress the sintering of precious metals at high temperature. In the same, precious metals can also enhance the redox performance and oxygen storage capacity of support. This paper reviews the reaction phenomenon and mechanism of precious metals (Pt, Pd, Rh) and supports such as Al 2 O 3 , CeO 2-based composite oxides.展开更多
HZSM-5, Al_2O_3, TiO_2 and SiO_2 supported CeO_2-ZrO_2-CrO_x catalysts were prepared by deposition-precipitation method and tested for deep catalytic oxidation of 1,2-dichloroethane（DCE）, as one of the common chlori...HZSM-5, Al_2O_3, TiO_2 and SiO_2 supported CeO_2-ZrO_2-CrO_x catalysts were prepared by deposition-precipitation method and tested for deep catalytic oxidation of 1,2-dichloroethane（DCE）, as one of the common chlorinated organic pollutants. All the catalysts were characterized by means of N_2 adsorption-desorption, X-ray photoelectron spectroscopy（XPS）, ammonia-temperatureprogrammed desorption（NH_3-TPD） and hydrogen temperature-programmed reduction（H2-TPR）. The characterization results revealed that there was strongly synergistic effect between the oxidizability of CZCr species and the acidity of supports, which obviously promoted the catalytic activity for DCE degradation. 20% CZCr/HZSM-5 showed the highest activity and good durability during the long-term continuous test. The catalytic activity decreased in the order： 20%CZCr/HZSM-5〉CZCr〉20%CZCr/TiO_2〉20%CZCr/Al_2O_3〉20%CZCr/SiO_2.展开更多
A co-precipitation method was employed to prepare Ni/Al_(2)O_(3)-ZrO_(2),Co/Al_(2)O_(3)-ZrO_(2)and Ni-Co/Al_(2)O_(3)-ZrO_(2)catalysts.Their properties were characterized by N_(2) adsorption(BET),thermogravimetric anal...A co-precipitation method was employed to prepare Ni/Al_(2)O_(3)-ZrO_(2),Co/Al_(2)O_(3)-ZrO_(2)and Ni-Co/Al_(2)O_(3)-ZrO_(2)catalysts.Their properties were characterized by N_(2) adsorption(BET),thermogravimetric analysis(TGA),temperature-programmed reduction(TPR),temperature-programmed desorption(CO_(2)-TPD),and temperature-programmed surface reaction(CH_(4)-TPSR and CO_(2)-TPSR).Ni-Co/Al_(2)O_(3)-ZrO_(2)bimetallic catalyst has good performance in the reduction of active components Ni,Co and CO_(2)adsorption.Compared with mono-metallic catalyst,bimetallic catalyst could provide more active sites and CO_(2)adsorption sites(C+CO_(2)=2CO)for the methane-reforming reaction,and a more appropriate force formed between active components and composite support(SMSI)for the catalytic reaction.According to the CH_(4)-CO_(2)-TPSR,there were 80.9%and 81.5%higher CH_(4) and CO_(2)conversion over Ni-Co/Al_(2)O_(3)-ZrO_(2)catalyst,and its better resistance to carbon deposition,less than 0.5%of coke after 4 h reaction,was found by TGA.The high activity and excellent anti-coking of the Ni-Co/Al_(2)O_(3)-ZrO_(2)catalyst were closely related to the synergy between Ni and Co active metal,the strong metal-support interaction and the use of composite support.展开更多
文摘Based on the γ-Al2O3 support with large-size pores, impregnation-deposition method was adopted to prepare the nano CeO_2/γ-Al2O3 composite supports. The results of XRD showed that there was no CeO_2-Al2O3 mixture or solid solution, indicating that CeO_2 was only loaded on the surface of Al2O3. The CeO_2/γ-Al2O3 composite support had larger specific surface area (170 m2·g-1), while for the non-loaded nanosized CeO_2, the specific surface area was small(～50 m2·g-1). The influence of impregnation and drying methods on the surface properties, thermal stability and crystal structure of composite supports was characterized by XRD, DTA and BET. The CeO_2/γ-Al2O3 composite support prepared by vacuum impregnation and microwave drying was better than that prepared by conventional impregnation and drying.
基金National Science technology Support Plan Projects"(2012BAE06B00)
文摘TWC-equipped exhausts are widely used in gasoline-fueled vehicles to meet stringent emission regulations. The main components in TWCs are precious metals such as palladium (Pd), platinum (Pt), and rhodium (Rh) as the active component, and inorganic oxides such as γ-alumina (Al 2 O 3 ), ceria (CeO 2 ), zirconia (ZrO 2 ) and ceria-zirconia (CeO 2-ZrO 2 ) are used as the support. Interaction of precious metals and support plays an important role in the thermal stability and catalytic performance of TWCs. The support can improve the dispersion of precious metals and suppress the sintering of precious metals at high temperature. In the same, precious metals can also enhance the redox performance and oxygen storage capacity of support. This paper reviews the reaction phenomenon and mechanism of precious metals (Pt, Pd, Rh) and supports such as Al 2 O 3 , CeO 2-based composite oxides.
基金Project supports from National Nature Science Foundation of China(21177110)
文摘HZSM-5, Al_2O_3, TiO_2 and SiO_2 supported CeO_2-ZrO_2-CrO_x catalysts were prepared by deposition-precipitation method and tested for deep catalytic oxidation of 1,2-dichloroethane（DCE）, as one of the common chlorinated organic pollutants. All the catalysts were characterized by means of N_2 adsorption-desorption, X-ray photoelectron spectroscopy（XPS）, ammonia-temperatureprogrammed desorption（NH_3-TPD） and hydrogen temperature-programmed reduction（H2-TPR）. The characterization results revealed that there was strongly synergistic effect between the oxidizability of CZCr species and the acidity of supports, which obviously promoted the catalytic activity for DCE degradation. 20% CZCr/HZSM-5 showed the highest activity and good durability during the long-term continuous test. The catalytic activity decreased in the order： 20%CZCr/HZSM-5〉CZCr〉20%CZCr/TiO_2〉20%CZCr/Al_2O_3〉20%CZCr/SiO_2.
基金supported by the National Basic Research Program of China(2005CB221207)the National Natural Science Foundation of China(Grants Nos.20846002,U0970134)+2 种基金the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT0517)the Program for New Century Excellent Talents in University(No.NCET-05-0267)the Ph.D.Programs Foundation for New Teacher(No.20091402120013)in Ministry of Education,China。
文摘A co-precipitation method was employed to prepare Ni/Al_(2)O_(3)-ZrO_(2),Co/Al_(2)O_(3)-ZrO_(2)and Ni-Co/Al_(2)O_(3)-ZrO_(2)catalysts.Their properties were characterized by N_(2) adsorption(BET),thermogravimetric analysis(TGA),temperature-programmed reduction(TPR),temperature-programmed desorption(CO_(2)-TPD),and temperature-programmed surface reaction(CH_(4)-TPSR and CO_(2)-TPSR).Ni-Co/Al_(2)O_(3)-ZrO_(2)bimetallic catalyst has good performance in the reduction of active components Ni,Co and CO_(2)adsorption.Compared with mono-metallic catalyst,bimetallic catalyst could provide more active sites and CO_(2)adsorption sites(C+CO_(2)=2CO)for the methane-reforming reaction,and a more appropriate force formed between active components and composite support(SMSI)for the catalytic reaction.According to the CH_(4)-CO_(2)-TPSR,there were 80.9%and 81.5%higher CH_(4) and CO_(2)conversion over Ni-Co/Al_(2)O_(3)-ZrO_(2)catalyst,and its better resistance to carbon deposition,less than 0.5%of coke after 4 h reaction,was found by TGA.The high activity and excellent anti-coking of the Ni-Co/Al_(2)O_(3)-ZrO_(2)catalyst were closely related to the synergy between Ni and Co active metal,the strong metal-support interaction and the use of composite support.
