✍ Scribed by F. Solymosi; J. Raskó; E. Papp; A. Oszkó; T. Bánsági
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The adsorption, decomposition and oxidation of CH3CI have been investigated on pure and chromiadoped SnO2 catalysts by means of infrared spectroscopy, mass spectrometric and gas chromatographic analysis. Catalyst samples have been characterized by X-ray photoelectron spectroscopy. It was found that the Cr 3 ÷ ions incorporated in the surface layer of SnO2 are oxidized to higher valent chromium ions. In harmony with the determination of active oxygen content, samples calcined at 873-973 K contained the largest concentration of higher valent chromium ions. Infrared spectroscopy showed that CHaC! interacts with the OH groups of SnO 2 at 200-300 K to form H-bridge-bonded alkyl chloride. The decomposition of CH3CI occurred slowly on pure SnO2 above 573 K to give CH4, n20, CO and HC1. The oxidation of CH3C1 on SnO2 proceeded at a measurable rate at 400 4A.0 K. Incorporation of a small amount of chromium ions into the SnO 2 increased the rate of both the decomposition and the oxidation by a factor of 10-16. The enhanced activity of chromia-doped SnO2 is attributed to the high reactivity of chromium ions in the surface layer of SnO2.
📜 SIMILAR VOLUMES
The C1 atom-initiated oxidation of CHzClz and CH3Cl was studied using the FTIR method in the photolysis of mixtures typically containing Clz and the chlorinated methanes at 1 torr each in 700 torr air. The results obtained from product analysis were in general agreement with those reported by Sanhue