Photocatalytic oxidation of gaseous pollutants with oxygen on semiconductor surfaces

In order to obtain a sufficient high conversion rate in flue gas cleaning p rocesses, catalysts are used in nearly all cases. The activation of these c lassical contacts is done by heat. On the other side it is known that semic onductor material can become catalytically active under irradiation with UV -light to accelerate combustion processes. Since in that case the oxidation process proceeds at room temperature, the use of a photocatalyst can yield some advantages in comparison to the application of thermal activated cata lysts, especially, for small combustion units. The problem, however, is tha t no useful information about the kinetics of photocatalytic combustion pro cesses or about the possibilities of the practical use of photocatalysts ex ists in the open literature. Using the combustion of propene as example, th ese problems are discussed in detail. Some practically useful solutions to the main problems are proposed.