Catalytic Decomposition of HO on CoO Doped with AgO or ZnO
The effects of doping Co 3 O 4 with Ag 2 O (0.40–3.00 mol%) or ZnO (0.75–6.00 mol%) on the surface and catalytic properties of the solid were investigated via nitrogen adsorption at −196°C and the decomposition of H 2 O 2 at 30–50°C. Pure and doped samples were prepared by the thermal decomposition...
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2000-10-01
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Series: | Adsorption Science & Technology |
Online Access: | https://doi.org/10.1260/0263617001493774 |
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doaj-821e3968e3994d8a8adf17eb57af51b52021-04-02T09:52:10ZengHindawi - SAGE PublishingAdsorption Science & Technology0263-61742048-40382000-10-011810.1260/0263617001493774Catalytic Decomposition of HO on CoO Doped with AgO or ZnOGamil A. El-Shobaky0Abd. El-Mohsen M. Turky1 Department of Physical Chemistry, National Research Centre, Dokki, Cairo, Egypt Department of Chemistry, Faculty of Science, Suez Canal University, Ismailia, EgyptThe effects of doping Co 3 O 4 with Ag 2 O (0.40–3.00 mol%) or ZnO (0.75–6.00 mol%) on the surface and catalytic properties of the solid were investigated via nitrogen adsorption at −196°C and the decomposition of H 2 O 2 at 30–50°C. Pure and doped samples were prepared by the thermal decomposition in air at 500–900°C of pure cobalt carbonate and carbonate samples treated with different proportions of silver or zinc nitrates. The results showed that Ag 2 O doping followed by precalcination at 500–900°C resulted in a significant decrease (ca. 25%) in the BET surface areas of the treated Co 3 O 4 samples. Treatment of Co 3 O 4 with ZnO followed by precalcination over the same temperature range effected a corresponding increase in the specific surface areas (ca. 28%). The addition of Ag 2 O to Co 3 O 4 effected a record increase in the corresponding catalytic activity towards the decomposition of H 2 O 2 . Thus, the maximum increase noted in the catalytic rate constant (k) measured at 30°C over Co 3 O 4 doped with 3.00 mol% Ag 2 O exhibited a 36-fold, 26-fold and 3.5-fold increase for catalysts precalcined at 500°C, 700°C and 900°C, respectively. Treatment of Co 3 O 4 with ZnO also effected an increase in the catalytic activity of the resulting solid. Thus, treatment of Co 3 O 4 with 6.00 mol% ZnO followed by precalcination at 500°C, 700°C and 900°C effected an increase of 109%, 28% and 36%, respectively, in the catalytic activity expressed in terms of the reaction rate constant measured at 30°C. The doping process did not modify the activation energy of the catalyzed reaction but increased the concentration of catalytically active constituents considerably without changing their energetic nature. Doping with Ag 2 O or ZnO led to an increase in the concentration of Co 3+ –Co 2+ ion pairs in the system and also generated corresponding Ag + –Co 2+ and Zn 2+ –Co 3+ ion pairs, thereby increasing the number of active constituents involved in the catalytic decomposition studied.https://doi.org/10.1260/0263617001493774 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Gamil A. El-Shobaky Abd. El-Mohsen M. Turky |
spellingShingle |
Gamil A. El-Shobaky Abd. El-Mohsen M. Turky Catalytic Decomposition of HO on CoO Doped with AgO or ZnO Adsorption Science & Technology |
author_facet |
Gamil A. El-Shobaky Abd. El-Mohsen M. Turky |
author_sort |
Gamil A. El-Shobaky |
title |
Catalytic Decomposition of HO on CoO Doped with AgO or ZnO |
title_short |
Catalytic Decomposition of HO on CoO Doped with AgO or ZnO |
title_full |
Catalytic Decomposition of HO on CoO Doped with AgO or ZnO |
title_fullStr |
Catalytic Decomposition of HO on CoO Doped with AgO or ZnO |
title_full_unstemmed |
Catalytic Decomposition of HO on CoO Doped with AgO or ZnO |
title_sort |
catalytic decomposition of ho on coo doped with ago or zno |
publisher |
Hindawi - SAGE Publishing |
series |
Adsorption Science & Technology |
issn |
0263-6174 2048-4038 |
publishDate |
2000-10-01 |
description |
The effects of doping Co 3 O 4 with Ag 2 O (0.40–3.00 mol%) or ZnO (0.75–6.00 mol%) on the surface and catalytic properties of the solid were investigated via nitrogen adsorption at −196°C and the decomposition of H 2 O 2 at 30–50°C. Pure and doped samples were prepared by the thermal decomposition in air at 500–900°C of pure cobalt carbonate and carbonate samples treated with different proportions of silver or zinc nitrates. The results showed that Ag 2 O doping followed by precalcination at 500–900°C resulted in a significant decrease (ca. 25%) in the BET surface areas of the treated Co 3 O 4 samples. Treatment of Co 3 O 4 with ZnO followed by precalcination over the same temperature range effected a corresponding increase in the specific surface areas (ca. 28%). The addition of Ag 2 O to Co 3 O 4 effected a record increase in the corresponding catalytic activity towards the decomposition of H 2 O 2 . Thus, the maximum increase noted in the catalytic rate constant (k) measured at 30°C over Co 3 O 4 doped with 3.00 mol% Ag 2 O exhibited a 36-fold, 26-fold and 3.5-fold increase for catalysts precalcined at 500°C, 700°C and 900°C, respectively. Treatment of Co 3 O 4 with ZnO also effected an increase in the catalytic activity of the resulting solid. Thus, treatment of Co 3 O 4 with 6.00 mol% ZnO followed by precalcination at 500°C, 700°C and 900°C effected an increase of 109%, 28% and 36%, respectively, in the catalytic activity expressed in terms of the reaction rate constant measured at 30°C. The doping process did not modify the activation energy of the catalyzed reaction but increased the concentration of catalytically active constituents considerably without changing their energetic nature. Doping with Ag 2 O or ZnO led to an increase in the concentration of Co 3+ –Co 2+ ion pairs in the system and also generated corresponding Ag + –Co 2+ and Zn 2+ –Co 3+ ion pairs, thereby increasing the number of active constituents involved in the catalytic decomposition studied. |
url |
https://doi.org/10.1260/0263617001493774 |
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