In situ Raman studies on the interaction of oxygen and methanol with an iodine‐modified electrolytic silver catalyst

In situ Raman spectroscopy was used to study the interaction of iodine-modified electrolytic silver with oxygen and methanol at atmospheric pressure at temperatures between 25 and 500°C. It is shown that the presence of iodine inhibits the formation of surface oxygen species corresponding to deep oxidation and reduces the vibrational wavenumber of the modes corresponding to surface oxygen species. Moreover, it is found that methanol can be adsorbed and reacted on the surface of the modified silver without the co-adsorption of oxygen, resulting in iodine-induced adsorption of methanol. The intermediates at various temperatures were identified as methoxy and formate groups. According to the results, the reaction pathways in the practical process were proposed and compared with the conclusion obtained from the system without iodine modification, and remarkably close agreement was observed. The detailed mechanism of the oxidative reaction of methanol and the promotion effect of iodine modifier on the working catalyst is also discussed. Copyright © 2002 John Wiley & Sons, Ltd.

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