Two analytical methods for the evaluation of photocatalytic oxidation and reduction abilities were developed using a photocatalytic microreactor; one is product analysis and the other is reaction rate analysis. Two simple organic conversion reactions were selected for the oxidation and reduction. Since the reactions were one-to-one conversions from the reactant species to the product species, the product analysis was simply performed using gas chromatography, and the reactions were monitored in situ in the photocatalytic microreactor using the UV absorption spectra. The partial oxidation and reduction abilities for each functional group can be judged from the yield and selectivity, and the corresponding reaction rate, while the total oxidation ability can be judged from the conversion. We demonstrated the application of these methods for several kinds of visible light photocatalysts.

Photocatalytic organic reactions were performed using automatic photocatalytic microreactor, where several open-end capillaries with photocatalytic materials coated inside were just soaked in a test tube including a reactant solution. Organic reactions of the alkyl radicals generated from carboxylic acids due to the photo-Kolbe reaction was studied, in analogy with the reactions using a photosensitizer. This methodology features the reusability of the reactor and an easy process for analysis due to easy separation of the reactant solution.Keywords Photocatalytic reaction, microreactor, decarboxylation