Titania-based composite catalysts were prepared through a sol-gel route employing multi-walled carbon nanotubes with different diameters. The materials were characterized using thermogravimetric analysis, nitrogen ads...Titania-based composite catalysts were prepared through a sol-gel route employing multi-walled carbon nanotubes with different diameters. The materials were characterized using thermogravimetric analysis, nitrogen adsorption-desorption isotherm, powder X-ray diffraction, scanning electron microscopy, and diffuse reflectance UV-Vis absorption spectra. The application of the catalysts to photocatalytic degradation of phenol was tested under UV-Vis irradiation. A synergetic effect on phenol removal was observed in case of composite catalysts, which was evaluated in terms of apparent rate constant, total organic carbon removal and photonic efficiency.展开更多
Nanostructured titanium dioxides were synthesized via various post-treatments of titanate nanofibers obtained from titanium precursors by hydrothermal reactions. The microstructures of TiO2 and supported Ru/TiO2 catal...Nanostructured titanium dioxides were synthesized via various post-treatments of titanate nanofibers obtained from titanium precursors by hydrothermal reactions. The microstructures of TiO2 and supported Ru/TiO2 catalysts were characterized with X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray analysis, and nitrogen adsorption isotherms. The phase structure, particle size, morphology, and specific surface area were determined. The supported Ru catalysts were applied for the selective methanation of CO in a hydrogen-rich stream. The results indicated that the Ru catalyst supported on rutile and TiO2-B exhibited higher catalytic performance than the counterpart supported on anatase, which suggested the distinct interaction between Ru nanoparticles and TiO2 resulting from different crystalline phases and morphology.展开更多
TiO2 nanosheets mainly exposed （001） facet were prepared through a hydrothermal process with HF as the morphology-directing agent. Ru and RuO2 species were loaded by photo-deposition methods to prepare the photocata...TiO2 nanosheets mainly exposed （001） facet were prepared through a hydrothermal process with HF as the morphology-directing agent. Ru and RuO2 species were loaded by photo-deposition methods to prepare the photocatalysts. The structural features of the catalysts were characterized by X-ray di raction, transmission electron microscopy, inductively cou-pled plasma atomic emission spectrum, and H2 Temperature-programmed reduction. The photocatalytic property was studied by the O2 evolution from water oxidation, which was examined with respect to the in uences of Ru contents as well as the oxidation and reduction treatments, suggesting the charge separation effect of the Ru species co-catalysts on di erent facets of TiO2 nanosheets. In contrast to Ru/TiO2 and RuO2/TiO2 with the single deposited co-catalyst, the optimized catalyst 0.5%Ru-1.0%RuO2/TiO2 with dual co-catalysts achieved a much improved catalytic performance, in terms of the synergetic effect of dual co-catalysts and the enhanced charge separation effect.展开更多
Multi-walled carbon nanotubes （MWCNT） supported Cu-Co composite oxides catalysts were prepared by an ultrasonication treatment-aided impregnation method. The structure prop-erties of the catalysts were characterized...Multi-walled carbon nanotubes （MWCNT） supported Cu-Co composite oxides catalysts were prepared by an ultrasonication treatment-aided impregnation method. The structure prop-erties of the catalysts were characterized by XRD, TEM, H2-TPR, XPS and Raman spectra, indicating the strong interactions between Cu and Co mixed oxides as well as between metal oxides and MWCNT support. The catalytic performance of CO removal in a H2-rich stream was examined. In contrast to the single Cu and Co catalyst, the unique performance was ob-served for Cu-Co composite catalysts, which features an unusual reaction pathway through the combination of CO preferential oxidation and CO methanation especially at high reac-tion temperature. The optimal catalyst with Cu/Co ratio of 1/8 can achieve the complete CO conversion in a wider temperature range of 150-250 ℃ under the space velocity as high as 120 L/（h·g）, which demonstrates a promising catalyst for the e ective CO removal in a H2-rich stream.展开更多
Novel Bi2MoO6/TiO2 heterojunction was fabricated by growing Bi2MoO6 nanosheets arrays on the vertically aligned TiO2 nanorods arrays via a two-step solvothermal method. The obtained Bi2MoO6/TiO2 hierarchical heterojun...Novel Bi2MoO6/TiO2 heterojunction was fabricated by growing Bi2MoO6 nanosheets arrays on the vertically aligned TiO2 nanorods arrays via a two-step solvothermal method. The obtained Bi2MoO6/TiO2 hierarchical heterojunction showed excellent visible light photoelectrochemical performance. Compared with the pure TiO2 and Bi2MoO6, the photocurrent density of the heterojunction was increased 57 and 29 times, respectively. Furthermore, the hydrogen generation rate of the Bi2MoO6/TiO2 for photoelectrocatalytic water-splitting was about 6 times higher than that of the pure Bi2MoO6. The improved performance can be attributed to the synergistic effects of enhanced absorption of visible light, increase of migration rate and separation efficiency of photo-induced carriers.展开更多
The three way catalysts (TWCs) promoters (Ce Zr)O 2, (Pr Ce Zr)O 2 and (Pr Zr)O 2 were prepared by sol gel like method. They were characterized by XRD, EXAFS and BET surface area determination. The reduction ...The three way catalysts (TWCs) promoters (Ce Zr)O 2, (Pr Ce Zr)O 2 and (Pr Zr)O 2 were prepared by sol gel like method. They were characterized by XRD, EXAFS and BET surface area determination. The reduction features of the promoters were measured by temperature programmed reduction (TPR) of H 2 to access the potential for the promoters containing praseodymia as oxygen storage component in three way catalyst. The (Pr Zr)O 2 cubic solid solution is formed at high temperature up to 800 ℃, which makes it more reducible than the (Ce Zr)O 2 solid solution. For the (Pr Ce Zr)O 2 samples, the ternary solid solution plays an important role in the reduction process. The performance of the three way catalysts with fully formulated Pt, Pd and Rh is proceeded by using both light off temperature under a stoichiometric gas composition and the conversion of CO, C 3H 6 and NO under changing air/fuel ratio at a constant reaction temperature 400 ℃ . The results indicate that a small amount of praseodymia doping into (Ce Zr)O 2 favors the light off temperature of C 3H 6 and NO, and all the catalysts containing praseodymia obviously exhibits enhanced width of S value for NO conversion at lean region ( S ≥1.00).展开更多
A series of three-way catalysts (TWCs),containing a small amount of precious metals (PMs,including Pt,Pd and Rh) and a large amount of promoters CeO2 and La2O3,were prepared with different precursor compounds and vari...A series of three-way catalysts (TWCs),containing a small amount of precious metals (PMs,including Pt,Pd and Rh) and a large amount of promoters CeO2 and La2O3,were prepared with different precursor compounds and various doped manners.Crystal phases,dispersion of cerium and lanthanum,textural structure and thermal stability of the catalysts were investigated by XRD,XPS and pore parameters determination.The catalytic performance was studied by the measurements of CO,C3H6 and NO conversions on dependence of temperature at stoichimetric number point (S=1.00),and from S=0.75 to 1.30 at 280℃ or 340℃ for fresh or aged samples,respectively.The correlation between the catalytic performance and the characteristics of fresh and aged samples were discussed.The results show that the sample,in which CeO2 and La2O3 are doped with mixed oxide powders,possesses poor dispersion and less thermal stability,and the conversions of NO and C3H6 are apparently lower than those of the samples aged at 850℃ The main reason is due to the lanthanum enrichment on the surface.The precious metals and cerium may be covered and enveloped,and the PMs located on the internal microporous surface where no cerium and lanthanum exist,are easier to sinter and oxidize.For the sample doped with La(NO3)3 and Ce(NO3)3 aqueous solutions,high dispersion and thermal stable CeO2 La2O3 solid solution on all the surface of microporous γ-Al2O3 is identified.The solid solution CeO2-La2O3 also possessed high dispersion in the sample doped with La2O3 powder and Ce(NO3)3 aqueous solution.The last two aged samples keep higher NO conversion at S≥1 region.展开更多
基金ACKNOWLEDGMENT This work was supported Science Foundation of China by the National Natural （No.20703042）.
文摘Titania-based composite catalysts were prepared through a sol-gel route employing multi-walled carbon nanotubes with different diameters. The materials were characterized using thermogravimetric analysis, nitrogen adsorption-desorption isotherm, powder X-ray diffraction, scanning electron microscopy, and diffuse reflectance UV-Vis absorption spectra. The application of the catalysts to photocatalytic degradation of phenol was tested under UV-Vis irradiation. A synergetic effect on phenol removal was observed in case of composite catalysts, which was evaluated in terms of apparent rate constant, total organic carbon removal and photonic efficiency.
基金V. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20703042）, the National Basic Research Program of China （No.2010 CB923300）, USTC-NSRL Association Funding （No.KY 2060030009）, and Fundamental Research Funds for the Central Universities （No.WK2060030010）.
文摘Nanostructured titanium dioxides were synthesized via various post-treatments of titanate nanofibers obtained from titanium precursors by hydrothermal reactions. The microstructures of TiO2 and supported Ru/TiO2 catalysts were characterized with X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray analysis, and nitrogen adsorption isotherms. The phase structure, particle size, morphology, and specific surface area were determined. The supported Ru catalysts were applied for the selective methanation of CO in a hydrogen-rich stream. The results indicated that the Ru catalyst supported on rutile and TiO2-B exhibited higher catalytic performance than the counterpart supported on anatase, which suggested the distinct interaction between Ru nanoparticles and TiO2 resulting from different crystalline phases and morphology.
文摘TiO2 nanosheets mainly exposed （001） facet were prepared through a hydrothermal process with HF as the morphology-directing agent. Ru and RuO2 species were loaded by photo-deposition methods to prepare the photocatalysts. The structural features of the catalysts were characterized by X-ray di raction, transmission electron microscopy, inductively cou-pled plasma atomic emission spectrum, and H2 Temperature-programmed reduction. The photocatalytic property was studied by the O2 evolution from water oxidation, which was examined with respect to the in uences of Ru contents as well as the oxidation and reduction treatments, suggesting the charge separation effect of the Ru species co-catalysts on di erent facets of TiO2 nanosheets. In contrast to Ru/TiO2 and RuO2/TiO2 with the single deposited co-catalyst, the optimized catalyst 0.5%Ru-1.0%RuO2/TiO2 with dual co-catalysts achieved a much improved catalytic performance, in terms of the synergetic effect of dual co-catalysts and the enhanced charge separation effect.
文摘Multi-walled carbon nanotubes （MWCNT） supported Cu-Co composite oxides catalysts were prepared by an ultrasonication treatment-aided impregnation method. The structure prop-erties of the catalysts were characterized by XRD, TEM, H2-TPR, XPS and Raman spectra, indicating the strong interactions between Cu and Co mixed oxides as well as between metal oxides and MWCNT support. The catalytic performance of CO removal in a H2-rich stream was examined. In contrast to the single Cu and Co catalyst, the unique performance was ob-served for Cu-Co composite catalysts, which features an unusual reaction pathway through the combination of CO preferential oxidation and CO methanation especially at high reac-tion temperature. The optimal catalyst with Cu/Co ratio of 1/8 can achieve the complete CO conversion in a wider temperature range of 150-250 ℃ under the space velocity as high as 120 L/（h·g）, which demonstrates a promising catalyst for the e ective CO removal in a H2-rich stream.
基金This work was supported by the National Natural Science Foundation of China （No.U1632273）.
文摘Novel Bi2MoO6/TiO2 heterojunction was fabricated by growing Bi2MoO6 nanosheets arrays on the vertically aligned TiO2 nanorods arrays via a two-step solvothermal method. The obtained Bi2MoO6/TiO2 hierarchical heterojunction showed excellent visible light photoelectrochemical performance. Compared with the pure TiO2 and Bi2MoO6, the photocurrent density of the heterojunction was increased 57 and 29 times, respectively. Furthermore, the hydrogen generation rate of the Bi2MoO6/TiO2 for photoelectrocatalytic water-splitting was about 6 times higher than that of the pure Bi2MoO6. The improved performance can be attributed to the synergistic effects of enhanced absorption of visible light, increase of migration rate and separation efficiency of photo-induced carriers.
文摘The three way catalysts (TWCs) promoters (Ce Zr)O 2, (Pr Ce Zr)O 2 and (Pr Zr)O 2 were prepared by sol gel like method. They were characterized by XRD, EXAFS and BET surface area determination. The reduction features of the promoters were measured by temperature programmed reduction (TPR) of H 2 to access the potential for the promoters containing praseodymia as oxygen storage component in three way catalyst. The (Pr Zr)O 2 cubic solid solution is formed at high temperature up to 800 ℃, which makes it more reducible than the (Ce Zr)O 2 solid solution. For the (Pr Ce Zr)O 2 samples, the ternary solid solution plays an important role in the reduction process. The performance of the three way catalysts with fully formulated Pt, Pd and Rh is proceeded by using both light off temperature under a stoichiometric gas composition and the conversion of CO, C 3H 6 and NO under changing air/fuel ratio at a constant reaction temperature 400 ℃ . The results indicate that a small amount of praseodymia doping into (Ce Zr)O 2 favors the light off temperature of C 3H 6 and NO, and all the catalysts containing praseodymia obviously exhibits enhanced width of S value for NO conversion at lean region ( S ≥1.00).
基金Project (No. 9712301) supported by Ford-China Research and Development Fund
文摘A series of three-way catalysts (TWCs),containing a small amount of precious metals (PMs,including Pt,Pd and Rh) and a large amount of promoters CeO2 and La2O3,were prepared with different precursor compounds and various doped manners.Crystal phases,dispersion of cerium and lanthanum,textural structure and thermal stability of the catalysts were investigated by XRD,XPS and pore parameters determination.The catalytic performance was studied by the measurements of CO,C3H6 and NO conversions on dependence of temperature at stoichimetric number point (S=1.00),and from S=0.75 to 1.30 at 280℃ or 340℃ for fresh or aged samples,respectively.The correlation between the catalytic performance and the characteristics of fresh and aged samples were discussed.The results show that the sample,in which CeO2 and La2O3 are doped with mixed oxide powders,possesses poor dispersion and less thermal stability,and the conversions of NO and C3H6 are apparently lower than those of the samples aged at 850℃ The main reason is due to the lanthanum enrichment on the surface.The precious metals and cerium may be covered and enveloped,and the PMs located on the internal microporous surface where no cerium and lanthanum exist,are easier to sinter and oxidize.For the sample doped with La(NO3)3 and Ce(NO3)3 aqueous solutions,high dispersion and thermal stable CeO2 La2O3 solid solution on all the surface of microporous γ-Al2O3 is identified.The solid solution CeO2-La2O3 also possessed high dispersion in the sample doped with La2O3 powder and Ce(NO3)3 aqueous solution.The last two aged samples keep higher NO conversion at S≥1 region.
