Effects of LiO Doping on the Surface and Catalytic Properties of CoO–FeO Solids Precalcined at Different Temperatures
The effects of Li 2 O treatment on the solid–solid interactions and the surface and catalytic properties of the Co 3 O 4 –Fe 2 O 3 system have been studied using TG, DTA and XRD methods, nitrogen adsorption studies at −196°C and the catalytic oxidation of CO by O 2 at 150–350°C. The results obtained...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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SAGE Publications
2000-04-01
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| Series: | Adsorption Science & Technology |
| Online Access: | https://doi.org/10.1260/0263617001493413 |
| _version_ | 1797283419828256768 |
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| author | G.A. El-Shobaky M.A. Shouman M.N. Alaya |
| author_facet | G.A. El-Shobaky M.A. Shouman M.N. Alaya |
| author_sort | G.A. El-Shobaky |
| collection | DOAJ |
| description | The effects of Li 2 O treatment on the solid–solid interactions and the surface and catalytic properties of the Co 3 O 4 –Fe 2 O 3 system have been studied using TG, DTA and XRD methods, nitrogen adsorption studies at −196°C and the catalytic oxidation of CO by O 2 at 150–350°C. The results obtained showed that Li 2 O doping followed by precalcination at 500–1000°C enhanced the formation of cobalt ferrite to an extent proportional to the amount of dopant added (0.52–6.0 mol% Li 2 O). The solid–solid interaction leading to the formation of CoFe 2 O 4 took place at temperatures ≥700°C in the presence of the Li 2 O dopant. Lithia doping modified the surface characteristics of the Co 3 O 4 –Fe 2 O 3 solids, both increasing and decreasing their BET surface areas depending on the amount of dopant added and the precalcination temperature employed for the treated solids. The activation energy of sintering (ΔE S ) of cobalt/ferric mixed oxides was determined for the pure and doped solids from the variation in their specific surface areas as a function of the precalcination temperature. Both an increase and a decrease in the value of ΔE S due to Li 2 O doping occurred depending on the amount of lithia added. The doping of Co 3 O 4 –FeO solids, followed by precalcination at 500°C, effected a significant increase (144%) in their catalytic activity towards CO oxidation by O 2 . Precalcination at 700–1000°C of the mixed oxide solids doped with Li 2 O (0.52 and 0.75 mol%) resulted in an increase in their catalytic activity which decreased upon increasing the amount of Li 2 O added above this limit. The activation energy of the catalyzed reaction was determined for the pure and variously doped solids studied. |
| first_indexed | 2024-03-07T17:31:47Z |
| format | Article |
| id | doaj.art-29e568b15a37474b93fd55c8f6aa2b33 |
| institution | Directory Open Access Journal |
| issn | 0263-6174 2048-4038 |
| language | English |
| last_indexed | 2024-03-07T17:31:47Z |
| publishDate | 2000-04-01 |
| publisher | SAGE Publications |
| record_format | Article |
| series | Adsorption Science & Technology |
| spelling | doaj.art-29e568b15a37474b93fd55c8f6aa2b332024-03-02T17:46:59ZengSAGE PublicationsAdsorption Science & Technology0263-61742048-40382000-04-011810.1260/0263617001493413Effects of LiO Doping on the Surface and Catalytic Properties of CoO–FeO Solids Precalcined at Different TemperaturesG.A. El-Shobaky0M.A. Shouman1M.N. Alaya2 Department of Physical Chemistry, National Research Centre, Dokki, Cairo, Egypt Department of Physical Chemistry, National Research Centre, Dokki, Cairo, Egypt Chemistry Department, Faculty of Science, University of Aleppo, Aleppo, SyriaThe effects of Li 2 O treatment on the solid–solid interactions and the surface and catalytic properties of the Co 3 O 4 –Fe 2 O 3 system have been studied using TG, DTA and XRD methods, nitrogen adsorption studies at −196°C and the catalytic oxidation of CO by O 2 at 150–350°C. The results obtained showed that Li 2 O doping followed by precalcination at 500–1000°C enhanced the formation of cobalt ferrite to an extent proportional to the amount of dopant added (0.52–6.0 mol% Li 2 O). The solid–solid interaction leading to the formation of CoFe 2 O 4 took place at temperatures ≥700°C in the presence of the Li 2 O dopant. Lithia doping modified the surface characteristics of the Co 3 O 4 –Fe 2 O 3 solids, both increasing and decreasing their BET surface areas depending on the amount of dopant added and the precalcination temperature employed for the treated solids. The activation energy of sintering (ΔE S ) of cobalt/ferric mixed oxides was determined for the pure and doped solids from the variation in their specific surface areas as a function of the precalcination temperature. Both an increase and a decrease in the value of ΔE S due to Li 2 O doping occurred depending on the amount of lithia added. The doping of Co 3 O 4 –FeO solids, followed by precalcination at 500°C, effected a significant increase (144%) in their catalytic activity towards CO oxidation by O 2 . Precalcination at 700–1000°C of the mixed oxide solids doped with Li 2 O (0.52 and 0.75 mol%) resulted in an increase in their catalytic activity which decreased upon increasing the amount of Li 2 O added above this limit. The activation energy of the catalyzed reaction was determined for the pure and variously doped solids studied.https://doi.org/10.1260/0263617001493413 |
| spellingShingle | G.A. El-Shobaky M.A. Shouman M.N. Alaya Effects of LiO Doping on the Surface and Catalytic Properties of CoO–FeO Solids Precalcined at Different Temperatures Adsorption Science & Technology |
| title | Effects of LiO Doping on the Surface and Catalytic Properties of CoO–FeO Solids Precalcined at Different Temperatures |
| title_full | Effects of LiO Doping on the Surface and Catalytic Properties of CoO–FeO Solids Precalcined at Different Temperatures |
| title_fullStr | Effects of LiO Doping on the Surface and Catalytic Properties of CoO–FeO Solids Precalcined at Different Temperatures |
| title_full_unstemmed | Effects of LiO Doping on the Surface and Catalytic Properties of CoO–FeO Solids Precalcined at Different Temperatures |
| title_short | Effects of LiO Doping on the Surface and Catalytic Properties of CoO–FeO Solids Precalcined at Different Temperatures |
| title_sort | effects of lio doping on the surface and catalytic properties of coo feo solids precalcined at different temperatures |
| url | https://doi.org/10.1260/0263617001493413 |
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