Influence of Surface Composition on Hydrogen Peroxide Decomposition Catalyzed by Co(II) Aminopyridine-Supported Compounds on Amorphous Silica Gel
✍ Scribed by Robson F. de Farias; Afonso S. Gonçalves; Claudio Airoldi
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 45 KB
- Volume
- 247
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
Cobalt compounds supported on 2-, 3-, and 4-aminopyridine-modified silica surfaces, named Sil2Co, Sil3Co, and Sil4Co, respectively, were used to catalyze the decomposition of hydrogen peroxide on ethanolic solutions at 293, 298, and 303 K. The calculated k values (x10(-4) s(-1)) for Sil2Co, Sil3Co, and Sil4Co are 0.65, 1.24, and 4.78 (293 K); 1.23, 1.87, and 6.33 (298 K); and 1.80, 2.80, and 10.30 (303 K), respectively. All obtained results evidence that such decomposition is a first-order reaction. Zinc-, nickel-, and copper-supported compounds were also tested, but exhibited a very low catalytic activity. By using the k values at 298 and 303 K, and employing the equation ln (k1/k2) = E(a)/R(1/T2-1/T1), the activation energy values for the considered reaction were Sil2Co = 57.20, Sil3Co = 60.60, and Sil4Co = 73.10 kJ mol(-1), respectively. The low values calculated for E(a) are in agreement with a free-radical mechanism.