Sulfur-containing compounds anodic processes

Notice that the sulfide ion, S, is oxidized very easily to elemental sulfur. This often causes problems, because sulfur adsorbs on the anode and poisons it (makes the process much less efficient or even impossible to continue the process). Generally, sulfur-containing compounds are avoided if possible in electrochemical work. 

Foods such as meat, fish, and some vegetables contain sulfur-bearing amino acids that form volatile sulfur compounds during processing and storage. When these compounds react with iron, a black precipitate forms on the container and in most instances darkens the food. A small piece of aluminum welded to the tinplate can has been used to prevent container corrosion and sulfide staining in commercially canned hams. In this case, the aluminum acts as a sacrificial anode and stops the reaction with tin and iron that otherwise could occur at the small exposed tinplate areas (14). 

The possibility to functionalize aromatic compounds by electrochemical methods is of great interest to chemical industry. Therefore, considerable efforts were made to develop the electrochemical oxidation of benzene to p-benzoquinone to the industrial scale thus forming a basis for a new hydroquinone process. The electrochemical oxidation of benzene in aqueous emulsions containing sulfuric acid using divided cells and Pb02 anodes formsp-benzoquinone. The product can then be reduced cathodically to yield hydroquinone in a paired synthesis. 

From the literature it is clear that nano-structured ceria has several advantages over similar microcrystalline materials. In SOFC applications, resistance to impurities such as sulfur, and resistance to carbon formation when hydrocarbons are used as fuel, have been reported. The high density of surface defects in nanostructured materials provides a large number of active sites for various surface interactions and surface exchange processes. There are clearly interesting features in nano-sized ceria compounds that need further exploration. The possibility of minimizing pretreatment and water vapor partial pressure in e.g. the natural gas feed due to lower susceptibility to coke formation of ceria containing fuel electrodes (anodes), may simplify the fuel cell system. 

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