Physicochemical, Surface and Catalytic Properties of CoO/AlO as Influenced by CeO or VO Doping
A pure Co 3 O 4 /Al 2 O 3 sample was prepared by the wet impregnation method using finely powdered aluminium hydroxide and cobalt nitrate dissolved in the least amount of distilled water. Maintaining the amount of Co 3 O 4 constant at 16.7 mol%, different samples were doped by impregnating with know...
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SAGE Publishing
2005-12-01
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| Series: | Adsorption Science & Technology |
| Online Access: | https://doi.org/10.1260/026361705775373233 |
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| author | H.G. El-Shobaky |
| author_facet | H.G. El-Shobaky |
| author_sort | H.G. El-Shobaky |
| collection | DOAJ |
| description | A pure Co 3 O 4 /Al 2 O 3 sample was prepared by the wet impregnation method using finely powdered aluminium hydroxide and cobalt nitrate dissolved in the least amount of distilled water. Maintaining the amount of Co 3 O 4 constant at 16.7 mol%, different samples were doped by impregnating with known amounts of cerium or vanadium nitrates prior to impregnation with cobalt nitrate. The pure and doped samples were precalcined at 600°C and 800°C, respectively. The dopant concentrations employed were 0.5, 1.0, 2.0 and 3.0 mol% CeO 2 or V 2 O 5 . The resulting materials were studied by XRD and EDX methods, N 2 adsorption at −196°C and CO oxidation by O 2 at 130–220°C. The results obtained revealed that the surface concentrations of cobalt species in pure and variously doped Co 3 O 4 /Al 2 O 3 solids precalcined at 600°C were more than twice those present in the bulk of these solids. Heating the doped solid at 600°C and 800°C increased the degree of dispersion of Co 3 O 4 by decreasing the crystallite size. This effect was more pronounced in the case of V 2 O 5 doping, with the surface concentration of cobalt species being increased to a greater extent than with CeO 2 doping. Similarly, heating the doped solid at 600°C resulted in a progressive but measurable increase in the lattice parameter of Co 3 O 4 due to the formation of solid solutions. On heating the V 2 O 5 -doped solid at 800°C, a portion of the added V 2 O 5 inter-acted with Co 3 O 4 to yield cobalt vanadate while the other portion contributed to the formation of a solid solution. Doping followed by heating at 600°C increased the catalytic activity of the doped solids in CO oxidation by O 2 . In contrast, solids precalcined at 800°C exhibited the opposite effect. The doping process changed the concentration of active sites involved in the catalytic reaction rather than changing the mechanism of the catalytic reaction. |
| format | Article |
| id | doaj-art-a052b47a45c743569bfcd13bf65e9d75 |
| institution | Kabale University |
| issn | 0263-6174 2048-4038 |
| language | English |
| publishDate | 2005-12-01 |
| publisher | SAGE Publishing |
| record_format | Article |
| series | Adsorption Science & Technology |
| spelling | doaj-art-a052b47a45c743569bfcd13bf65e9d752025-01-02T22:37:55ZengSAGE PublishingAdsorption Science & Technology0263-61742048-40382005-12-012310.1260/026361705775373233Physicochemical, Surface and Catalytic Properties of CoO/AlO as Influenced by CeO or VO DopingH.G. El-ShobakyA pure Co 3 O 4 /Al 2 O 3 sample was prepared by the wet impregnation method using finely powdered aluminium hydroxide and cobalt nitrate dissolved in the least amount of distilled water. Maintaining the amount of Co 3 O 4 constant at 16.7 mol%, different samples were doped by impregnating with known amounts of cerium or vanadium nitrates prior to impregnation with cobalt nitrate. The pure and doped samples were precalcined at 600°C and 800°C, respectively. The dopant concentrations employed were 0.5, 1.0, 2.0 and 3.0 mol% CeO 2 or V 2 O 5 . The resulting materials were studied by XRD and EDX methods, N 2 adsorption at −196°C and CO oxidation by O 2 at 130–220°C. The results obtained revealed that the surface concentrations of cobalt species in pure and variously doped Co 3 O 4 /Al 2 O 3 solids precalcined at 600°C were more than twice those present in the bulk of these solids. Heating the doped solid at 600°C and 800°C increased the degree of dispersion of Co 3 O 4 by decreasing the crystallite size. This effect was more pronounced in the case of V 2 O 5 doping, with the surface concentration of cobalt species being increased to a greater extent than with CeO 2 doping. Similarly, heating the doped solid at 600°C resulted in a progressive but measurable increase in the lattice parameter of Co 3 O 4 due to the formation of solid solutions. On heating the V 2 O 5 -doped solid at 800°C, a portion of the added V 2 O 5 inter-acted with Co 3 O 4 to yield cobalt vanadate while the other portion contributed to the formation of a solid solution. Doping followed by heating at 600°C increased the catalytic activity of the doped solids in CO oxidation by O 2 . In contrast, solids precalcined at 800°C exhibited the opposite effect. The doping process changed the concentration of active sites involved in the catalytic reaction rather than changing the mechanism of the catalytic reaction.https://doi.org/10.1260/026361705775373233 |
| spellingShingle | H.G. El-Shobaky Physicochemical, Surface and Catalytic Properties of CoO/AlO as Influenced by CeO or VO Doping Adsorption Science & Technology |
| title | Physicochemical, Surface and Catalytic Properties of CoO/AlO as Influenced by CeO or VO Doping |
| title_full | Physicochemical, Surface and Catalytic Properties of CoO/AlO as Influenced by CeO or VO Doping |
| title_fullStr | Physicochemical, Surface and Catalytic Properties of CoO/AlO as Influenced by CeO or VO Doping |
| title_full_unstemmed | Physicochemical, Surface and Catalytic Properties of CoO/AlO as Influenced by CeO or VO Doping |
| title_short | Physicochemical, Surface and Catalytic Properties of CoO/AlO as Influenced by CeO or VO Doping |
| title_sort | physicochemical surface and catalytic properties of coo alo as influenced by ceo or vo doping |
| url | https://doi.org/10.1260/026361705775373233 |
| work_keys_str_mv | AT hgelshobaky physicochemicalsurfaceandcatalyticpropertiesofcooaloasinfluencedbyceoorvodoping |