Photon Flux and Wavelength Effects on the Selectivity and Product Yields of the Photocatalytic Air Oxidation of Neat Cyclohexane on TiO2 Particles

• Published in: The journal of physical chemistry. B 2005-02, Vol.109 (5), p.1914-1918
• Main Authors: Brusa, Marta A, Grela, Maria A
• Format: Article
• Language: English
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp045602+

Product selectivity and yields of cyclohexanol and cyclohexanone formation in the photocatalytic air oxidation of cyclohexane on TiO2 particles were determined as a function of the irradiation wavelength (254 ≤ λ/nm ≤ 366) and the photon flux (0.3 ≤ I 0/neinstein cm-2 s-1 ≤ 5.0). Photonic efficiencies for total monooxygenated products (cyclohexanol + cyclohexanone) ranged from 10 to 25% depending on photon energy and fluency. The cyclohexanol-to-cyclohexanone ratio linearly increases with the incident photon flux at each wavelength and varies more than a magnitude orderfrom 3 to 32%at the same incident photon fluency5 neinstein cm-2 s-1by changing the irradiation wavelength from 366 to 303 nm. Experimental evidence indicates that both spectral and intensity effects emerge as a consequence of the change in the frequency of photon absorption per particle. A mechanism is proposed which accounts for the origin of the selectivity changes.