2002 Volume 14 Issue 2 Pages 2_9-2_17
Photocatalytic decompositions of formic acid were performed by use of two types of photocatalytic reactors (Reactor I and II) and the influences of film-diffusional resistance and UV-light penetration on the reactor activity were studied both experimentally and theoretically. Reactor I is an annular-flow type with a 6-W blacklight blue fluorescent lamp (BL). In Reactor II, four glass tubes of 23 mm in inside diameter, each of which has an insertion of 6-W BL, are arranged in parallel in a glass tube of 92 mm in inside diameter. The inside or outside surfaces of these glass tubes are coated with a thin film of TiO2. All the reaction experiments were carried out in a batch-recirculation mode. The experimental result shows that in Reactor II, the UV light that penetrated through the glass tube and then the flowing reaction mixture acted on the photocatalyst immobilized on the surfaces of the neighboring glass tubes and greatly contributed to an enhancement in the reactor activity. In Reactor I, the film-diffusional resistance was certainly reduced with the increase of flow rate because it was easy to operate the reactor at a very high flow rate (2888 m h-1). The simulated result indicates that if Reactor II is possible to operate at a high flow rate, the reactor activity is increased by about 7.5 times compared with that of the present reactor and also by 2.2 times compared with that of Reactor I.
