微纳米α-Al2O3是一种重要的功能材料,因其优异的硬度、耐磨性、耐腐蚀性和高热稳定性,在表面涂层领域得到了广泛应用。随着微纳米技术的发展,微纳米级α-Al2O3作为添加剂在各涂层体系中的应用得到了深入研究,显示出其能够显著改善涂层...微纳米α-Al2O3是一种重要的功能材料,因其优异的硬度、耐磨性、耐腐蚀性和高热稳定性,在表面涂层领域得到了广泛应用。随着微纳米技术的发展,微纳米级α-Al2O3作为添加剂在各涂层体系中的应用得到了深入研究,显示出其能够显著改善涂层性能的潜力。微纳米α-Al2O3颗粒具有较大的比表面积和表面活性,能够增强涂层的机械性能,如硬度和耐磨性,同时提高涂层的耐腐蚀性和耐高温性能。微纳米α-Al2O3也是一种极优良的改性材料,其与有机硅烷、树脂等材料复合改性,既能大幅提升转化膜的应用效果,对其稳定性和耐候性也有较大的促进作用。在金属表面涂层、陶瓷涂层以及复合材料涂层中,微纳米α-Al2O3添加剂被广泛用于提高涂层的使用寿命和稳定性。此外,它在电子器件、航天航空和汽车工业等高技术领域也展现了广阔的应用前景。未来,随着表面技术的发展,微纳米α-Al2O3无铬钝化领域的市场应用将大幅增长,与其他功能性材料的协同作用和复合材料开发也将成为研究的重点。Micro-nano α-Al2O3 is an important functional material, because of its excellent hardness, wear resistance, corrosion resistance and high thermal stability, has been widely used in the field of surface coating. With the development of micro-nano technology, the application of micro-nano α-Al2O3 as an additive in various coating systems has been deeply studied, showing its potential to significantly improve coating properties. Micro-nano α-Al2O3 particles have a large specific surface area and surface activity, which can enhance the mechanical properties of the coating, such as hardness and wear resistance, while improving the corrosion resistance and high temperature resistance of the coating. Micro-nano α-Al2O3 is also an excellent modified material, and its composite modification with organosilane, resin and other materials can greatly improve the application effect of conversion film, and also has a greater role in promoting its stability and weather resistance. In metal surface coatings, ceramic coatings and composite coatings, micro-nano α-Al2O3 additives are widely used to improve the service life and stability of coatings. In addition, it also shows broad application prospects in high-tech fields such as electronic devices, aerospace and automotive industries. In the future, with the development of surface technology, the market application of micro-nano α-Al2O3 chromium-free passivation will grow significantly, and the synergy with other functional materials and the development of composite materials will also become the focus of research.展开更多
Composite supports CeO2-ZrO2-Al2O3(CZA) and CeO2-ZrO2-Al2O3-La2O3(CZALa) were prepared by co-precipitation method. Palladium catalysts were prepared by impregnation and their purification ability for CH4, CO and N...Composite supports CeO2-ZrO2-Al2O3(CZA) and CeO2-ZrO2-Al2O3-La2O3(CZALa) were prepared by co-precipitation method. Palladium catalysts were prepared by impregnation and their purification ability for CH4, CO and NOx in the mixture gas simulated the exhaust from natural gas vehicles (NGVs) operated under stoichiometric condition was investigated. The effect of La2O3 on the physicochemical properties of supports and catalysts was characterized by various techniques. The characterizations with X-ray diffraction (XRD) and Raman spectroscopy revealed that the doping of La2O3 restrained effectively the sintering of crystallite particles, maintained the crystallite particles in nanoscale and stabilized the crystal phase after calcination at 1000 ℃. The results of N2-adsorption, H2-temperatnre-programmed reduction (H2-TPR) and oxygen storage capacity (OSC) measurements indicated that La2O3 improved the textural properties, reducibility and OSC of composite supports. Activity testing results showed that the catalysts exhibit excellent activities for the simultaneous removal of methane, CO and NOx in the simulated exhaust gas. The catalysts supported on CZALa showed remarkable thermal stability and catalytic activity for the three pollutants, especially for NOx. The prepared palladium catalysts have high ability to remove NOx, CH4 and CO, and they can be used as excellent catalysts for the purification of exhaust from NGVs operated under stoichiometric condition. The catalysts reported in this work also have significant potential in industrial application because of their high performance and low cost.展开更多
The catalytic activity measurement for the NO+CO reaction over CuO/CeO\-2/\%γ\%\|Al\-2O\-3 catalysts at a low\|temperature(200 ℃) shows that the activity is strongly related to ceria loading amount, and both surface...The catalytic activity measurement for the NO+CO reaction over CuO/CeO\-2/\%γ\%\|Al\-2O\-3 catalysts at a low\|temperature(200 ℃) shows that the activity is strongly related to ceria loading amount, and both surface dispersed ceria species and crystalline CeO\-2 shows a significant enhancement on the activity. The effect of ceria species is contributed to their promoting the reduction of copper oxide species.展开更多
CeO2-based oxygen materials were prepared with co-precipitation method and characterized via Brunauer-Emmet Teller(BET)method,X-ray diffraction(XRD)and temperature-programmed reduction(H2-TPR).This paper revealed that...CeO2-based oxygen materials were prepared with co-precipitation method and characterized via Brunauer-Emmet Teller(BET)method,X-ray diffraction(XRD)and temperature-programmed reduction(H2-TPR).This paper revealed that three CeO2-based oxygen storage materials are all forming homogeneous solid solution.Among the samples,CeO2-ZrO2-Al2O3(CZA)has the best textural properties and excellent thermal stability.The specific surface area and pore volume of aged CZA are 90 m2/g and 0.29 mL/g.We proposed a viewpoint:Al3+ might insert among the interspace of fluorite structure or highly dispersal in solid solutions.展开更多
Ce-Zr-Al-Nd2O3 (CZAN) support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffTaction (XRD), low temperature nitrogen adsorption-desorption,...Ce-Zr-Al-Nd2O3 (CZAN) support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffTaction (XRD), low temperature nitrogen adsorption-desorption, oxygen pulsing technique, H2-temperamre programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The Pd-only three-way catalysts (Pd-TWC) supported on these materials were prepared by incipient wetness method and studied by activity tests. The results demonstrated that the CZAN supports obtained by the two methods showed better structural, textural and redox properties than the CZA without Nd2O3, and the addition of Nd203 improved the catalytic activity of TWC. Especially, the CZAN-i support prepared by impregnation method had better thermal stability and redox property. Meanwhile, the Pd/CZAN-i catalyst exhibited the best catalytic performance. XPS measurements indicated that the Nd-modified samples possessed more Ce3+ and oxygen vacancies on the surface of samples, which led to a better redox property. The excellent redox property of support materials helped to improve the catalytic activity of TWC.展开更多
MnOx-CeO2-Al2O3 mixed oxides were prepared by impregnating manganese and cerium precursors on alumina powders via a sol- gel deposition method. The oxide catalyst exhibited a poor resistance to sulfur dioxide after th...MnOx-CeO2-Al2O3 mixed oxides were prepared by impregnating manganese and cerium precursors on alumina powders via a sol- gel deposition method. The oxide catalyst exhibited a poor resistance to sulfur dioxide after the treatment in 100 ppm SO2/air at 350 °C for 50 h. The formation of manganese sulfate and especially cerium sulfate reduced the availability of surface active metal oxides, blocked the pore structure and decreased the surface area of the catalyst. These changes in chemical and structural and textural properties resulted in a severe loss in the activities of the sulfated catalyst for NO and soot oxidation. The decomposition of sulfates was almost complete during the calcina-tion in air at 800 °C for 30 min, which partially recovered the surface active sites and the catalyst surface area despite the significant sintering of metal oxides. Consequently, the NOx-assisted soot oxidation activity of the catalyst was regenerated to some extent by the oxidation treatment.展开更多
Nickel catalysts supported on CeO2-ZrO2-CeO2,ZrO2-Al2O3 and Al2O3 were prepared and characterized by means of X-ray diffraction(XRD),BET areas,H2 temperature-programmed reduction(H2-TPR),and X-ray photoelectron sp...Nickel catalysts supported on CeO2-ZrO2-CeO2,ZrO2-Al2O3 and Al2O3 were prepared and characterized by means of X-ray diffraction(XRD),BET areas,H2 temperature-programmed reduction(H2-TPR),and X-ray photoelectron spectroscopy(XPS).Through the test of catalytic partial oxidation of methane(CPOM),Ni/CeO2-ZrO2-Al2O3 displayed the highest activity,which resulted from its largest BET area and best NiO dispersion.Furthermore,Ni/CeO2-ZrO2-Al2O3 maintained a long-time stability in CPOM,which was attributed to its best coking resistance among all the prepared catalysts.展开更多
The Pd-only catalysts for motorcycle were prepared by impregnating CeO2-ZrO2-Al2O3 and CeO2-ZrO2+Al2O3 with PdCl2 aqueous solution and characterized by X-ray diffraction (XRD), oxygen storage capacity (OSC) and H2-tem...The Pd-only catalysts for motorcycle were prepared by impregnating CeO2-ZrO2-Al2O3 and CeO2-ZrO2+Al2O3 with PdCl2 aqueous solution and characterized by X-ray diffraction (XRD), oxygen storage capacity (OSC) and H2-temperature-programmed reduction (H2-TPR) methods. The XRD result indicated that the CeO2-ZrO2-Al2O3 compound prepared by co-precipitation formed a single solid solution and had good thermal stability, and Pd phase was not observed in all catalysts. The TPR results showed that the reduction temperature of Pd/CeO2-ZrO2-Al2O3 catalyst was lower than that of Pd/CeO2-ZrO2+Al2O3 catalyst whether they were fresh or aged catalysts. The Pd/CeO2-ZrO2-Al2O3 exhibited high three-way catalytic activity at low temperature, high thermal stability, and wide working window, suggesting a great potential for applications.展开更多
摘要微纳米α-Al2O3是一种重要的功能材料,因其优异的硬度、耐磨性、耐腐蚀性和高热稳定性,在表面涂层领域得到了广泛应用。随着微纳米技术的发展,微纳米级α-Al2O3作为添加剂在各涂层体系中的应用得到了深入研究,显示出其能够显著改善涂层性能的潜力。微纳米α-Al2O3颗粒具有较大的比表面积和表面活性,能够增强涂层的机械性能,如硬度和耐磨性,同时提高涂层的耐腐蚀性和耐高温性能。微纳米α-Al2O3也是一种极优良的改性材料,其与有机硅烷、树脂等材料复合改性,既能大幅提升转化膜的应用效果,对其稳定性和耐候性也有较大的促进作用。在金属表面涂层、陶瓷涂层以及复合材料涂层中,微纳米α-Al2O3添加剂被广泛用于提高涂层的使用寿命和稳定性。此外,它在电子器件、航天航空和汽车工业等高技术领域也展现了广阔的应用前景。未来,随着表面技术的发展,微纳米α-Al2O3无铬钝化领域的市场应用将大幅增长,与其他功能性材料的协同作用和复合材料开发也将成为研究的重点。Micro-nano α-Al2O3 is an important functional material, because of its excellent hardness, wear resistance, corrosion resistance and high thermal stability, has been widely used in the field of surface coating. With the development of micro-nano technology, the application of micro-nano α-Al2O3 as an additive in various coating systems has been deeply studied, showing its potential to significantly improve coating properties. Micro-nano α-Al2O3 particles have a large specific surface area and surface activity, which can enhance the mechanical properties of the coating, such as hardness and wear resistance, while improving the corrosion resistance and high temperature resistance of the coating. Micro-nano α-Al2O3 is also an excellent modified material, and its composite modification with organosilane, resin and other materials can greatly improve the application effect of conversion film, and also has a greater role in promoting its stability and weather resistance. In metal surface coatings, ceramic coatings and composite coatings, micro-nano α-Al2O3 additives are widely used to improve the service life and stability of coatings. In addition, it also shows broad application prospects in high-tech fields such as electronic devices, aerospace and automotive industries. In the future, with the development of surface technology, the market application of micro-nano α-Al2O3 chromium-free passivation will grow significantly, and the synergy with other functional materials and the development of composite materials will also become the focus of research.
基金supported by the National Natural Science Foundation of China (No. 20773090, 20803049)the National High Technology Researchand Development Program of China (863 Program, No. 2006AA06Z347)the Specialized Research Fund for the Doctoral Program of Higher Education(20070610026)
摘要Composite supports CeO2-ZrO2-Al2O3(CZA) and CeO2-ZrO2-Al2O3-La2O3(CZALa) were prepared by co-precipitation method. Palladium catalysts were prepared by impregnation and their purification ability for CH4, CO and NOx in the mixture gas simulated the exhaust from natural gas vehicles (NGVs) operated under stoichiometric condition was investigated. The effect of La2O3 on the physicochemical properties of supports and catalysts was characterized by various techniques. The characterizations with X-ray diffraction (XRD) and Raman spectroscopy revealed that the doping of La2O3 restrained effectively the sintering of crystallite particles, maintained the crystallite particles in nanoscale and stabilized the crystal phase after calcination at 1000 ℃. The results of N2-adsorption, H2-temperatnre-programmed reduction (H2-TPR) and oxygen storage capacity (OSC) measurements indicated that La2O3 improved the textural properties, reducibility and OSC of composite supports. Activity testing results showed that the catalysts exhibit excellent activities for the simultaneous removal of methane, CO and NOx in the simulated exhaust gas. The catalysts supported on CZALa showed remarkable thermal stability and catalytic activity for the three pollutants, especially for NOx. The prepared palladium catalysts have high ability to remove NOx, CH4 and CO, and they can be used as excellent catalysts for the purification of exhaust from NGVs operated under stoichiometric condition. The catalysts reported in this work also have significant potential in industrial application because of their high performance and low cost.
摘要The catalytic activity measurement for the NO+CO reaction over CuO/CeO\-2/\%γ\%\|Al\-2O\-3 catalysts at a low\|temperature(200 ℃) shows that the activity is strongly related to ceria loading amount, and both surface dispersed ceria species and crystalline CeO\-2 shows a significant enhancement on the activity. The effect of ceria species is contributed to their promoting the reduction of copper oxide species.
摘要CeO2-based oxygen materials were prepared with co-precipitation method and characterized via Brunauer-Emmet Teller(BET)method,X-ray diffraction(XRD)and temperature-programmed reduction(H2-TPR).This paper revealed that three CeO2-based oxygen storage materials are all forming homogeneous solid solution.Among the samples,CeO2-ZrO2-Al2O3(CZA)has the best textural properties and excellent thermal stability.The specific surface area and pore volume of aged CZA are 90 m2/g and 0.29 mL/g.We proposed a viewpoint:Al3+ might insert among the interspace of fluorite structure or highly dispersal in solid solutions.
基金Project supported by National Natural Science Foundation of China (20773090, 20803049)the Specialized Research Fund for the Doctoral Program of Higher Education (20070610026, 200806100009)
摘要Ce-Zr-Al-Nd2O3 (CZAN) support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffTaction (XRD), low temperature nitrogen adsorption-desorption, oxygen pulsing technique, H2-temperamre programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS). The Pd-only three-way catalysts (Pd-TWC) supported on these materials were prepared by incipient wetness method and studied by activity tests. The results demonstrated that the CZAN supports obtained by the two methods showed better structural, textural and redox properties than the CZA without Nd2O3, and the addition of Nd203 improved the catalytic activity of TWC. Especially, the CZAN-i support prepared by impregnation method had better thermal stability and redox property. Meanwhile, the Pd/CZAN-i catalyst exhibited the best catalytic performance. XPS measurements indicated that the Nd-modified samples possessed more Ce3+ and oxygen vacancies on the surface of samples, which led to a better redox property. The excellent redox property of support materials helped to improve the catalytic activity of TWC.
基金Project supported by National Natural Science Foundation of China (51072096)National Program on Key Basic Research Project (973 program)(2010CB732304)
摘要MnOx-CeO2-Al2O3 mixed oxides were prepared by impregnating manganese and cerium precursors on alumina powders via a sol- gel deposition method. The oxide catalyst exhibited a poor resistance to sulfur dioxide after the treatment in 100 ppm SO2/air at 350 °C for 50 h. The formation of manganese sulfate and especially cerium sulfate reduced the availability of surface active metal oxides, blocked the pore structure and decreased the surface area of the catalyst. These changes in chemical and structural and textural properties resulted in a severe loss in the activities of the sulfated catalyst for NO and soot oxidation. The decomposition of sulfates was almost complete during the calcina-tion in air at 800 °C for 30 min, which partially recovered the surface active sites and the catalyst surface area despite the significant sintering of metal oxides. Consequently, the NOx-assisted soot oxidation activity of the catalyst was regenerated to some extent by the oxidation treatment.
基金Project supported by State Key Fundamental Research Project(G1999022400)
摘要Nickel catalysts supported on CeO2-ZrO2-CeO2,ZrO2-Al2O3 and Al2O3 were prepared and characterized by means of X-ray diffraction(XRD),BET areas,H2 temperature-programmed reduction(H2-TPR),and X-ray photoelectron spectroscopy(XPS).Through the test of catalytic partial oxidation of methane(CPOM),Ni/CeO2-ZrO2-Al2O3 displayed the highest activity,which resulted from its largest BET area and best NiO dispersion.Furthermore,Ni/CeO2-ZrO2-Al2O3 maintained a long-time stability in CPOM,which was attributed to its best coking resistance among all the prepared catalysts.
基金Project supported by the National High Technology Research and Development Program of China (863 Program,2006AA06Z347)the Specialized Research Fund for the Doctoral Program of Higher Education (20070610026)
摘要The Pd-only catalysts for motorcycle were prepared by impregnating CeO2-ZrO2-Al2O3 and CeO2-ZrO2+Al2O3 with PdCl2 aqueous solution and characterized by X-ray diffraction (XRD), oxygen storage capacity (OSC) and H2-temperature-programmed reduction (H2-TPR) methods. The XRD result indicated that the CeO2-ZrO2-Al2O3 compound prepared by co-precipitation formed a single solid solution and had good thermal stability, and Pd phase was not observed in all catalysts. The TPR results showed that the reduction temperature of Pd/CeO2-ZrO2-Al2O3 catalyst was lower than that of Pd/CeO2-ZrO2+Al2O3 catalyst whether they were fresh or aged catalysts. The Pd/CeO2-ZrO2-Al2O3 exhibited high three-way catalytic activity at low temperature, high thermal stability, and wide working window, suggesting a great potential for applications.