Photocatalytic degradation of butanone (methylethylketone) in a small-size TiO2/β-SiC alveolar foam LED reactor

摘要

The feasibility of using Light Emitting Diodes (LEDs) as irradiation light source instead of usual conventional UV-A fluorescent light tube has been investigated for designing greener and small-size photocatalytic device for air purifying treatment. LEDs benefit from a high electricity-to-light yield, from the absence of any mercury, from strength and long lifetime, from the use of direct current power source and from an almost complete recycling. It was evidenced that the LED emission wavelengths need to carefully match with the absorption range of the photocatalyst, so that the use of widespread UV/vis 392 nm emission wavelength LEDs required its association with visible-light responsive TiO2 MPT623 from ISK in place of TiO2 P25. Thus, taking the gas phase methylethylketone degradation as test reaction, tests performed in a single-pass flow mode and in recirculation evidenced that the matching of UV/vis 392 nm emission wavelength LEDs to TiO2 MPT623 was promising. It allowed, without any loss of performances, engineering a 133 cm~3 small-size 56 LED photoreactor - interesting notably in terms of system miniaturization and configuration flexibility -, in which a medium surface area open-cell β-SiC alveolar foam was used as structured photocatalyst support for TiO2. The results illustrated the interest of using a supporting solid alveolar foam and small-size UV/vis LEDs adapted to the TiO2 photocatalyst absorption range. TiO2 MPT623/LEDs systems displayed energy effectiveness coefficients of about 50 times higher than that of TiO2 P25/UV-A system, so that they could be considered as a valuable alternative in the search for energy saving technologies.