TY - JOUR
T1 - Product desorption limitations in selective photocatalytic oxidation
AU - Renckens, T.J.A.
AU - Almeida, A.R.
AU - Damen, M.R.
AU - Kreutzer, M.T.
AU - Mul, G.
N1 - Special issue: Catalysis in membrane reactors. Proceedings of the 9th International Conference on Catalysis in Membrane Reactors. Lyon-Villeurbanne, France, 28th June - 2nd July 2009 organized by IRCELYON (UMR 5256 CNRS-UCBL1) at Claude Bernard Lyon 1 University University of LYON
PY - 2010/10/15
Y1 - 2010/10/15
N2 - The rate of photocatalytic processes can be significantly improved if strongly bound products rapidly desorb to free up active sites. This paper deals with the rate of desorption of cyclohexanone, the product of the liquid-phase photo-oxidation of cyclohexane. Dynamic step-response and pulse-response experiments were performed, and the interaction with a TiO2 surface was monitored using ATR FT-IR spectroscopy. A key result is that cyclohexanone desorbs readily from unexposed surfaces and desorbs an order of magnitude slower from UV-illuminated titania. The modification of the surface by UV is reversible: after 2 h without UV illumination the surface behaves as an unexposed one. The spectroscopic data support an explanation where without illumination, the cyclohexanone adsorbs on surface-bound water, from which it readily desorbs. Illumination, on the other hand, converts part of this water to accessible hydroxyl groups on titania. Cyclohexanone, forming during illumination, binds to these Ti-OH groups, and consequently desorbs much slower.
AB - The rate of photocatalytic processes can be significantly improved if strongly bound products rapidly desorb to free up active sites. This paper deals with the rate of desorption of cyclohexanone, the product of the liquid-phase photo-oxidation of cyclohexane. Dynamic step-response and pulse-response experiments were performed, and the interaction with a TiO2 surface was monitored using ATR FT-IR spectroscopy. A key result is that cyclohexanone desorbs readily from unexposed surfaces and desorbs an order of magnitude slower from UV-illuminated titania. The modification of the surface by UV is reversible: after 2 h without UV illumination the surface behaves as an unexposed one. The spectroscopic data support an explanation where without illumination, the cyclohexanone adsorbs on surface-bound water, from which it readily desorbs. Illumination, on the other hand, converts part of this water to accessible hydroxyl groups on titania. Cyclohexanone, forming during illumination, binds to these Ti-OH groups, and consequently desorbs much slower.
KW - Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR FT-IR)
KW - Operando spectroscopy
KW - Photocatalysis
KW - Surface characterization
KW - Transient experiments
KW - Unsteady-state processes
KW - n/a OA procedure
UR - http://www.scopus.com/inward/record.url?scp=77956872339&partnerID=8YFLogxK
U2 - 10.1016/j.cattod.2009.12.002
DO - 10.1016/j.cattod.2009.12.002
M3 - Article
SN - 0920-5861
VL - 155
SP - 302
EP - 310
JO - Catalysis today
JF - Catalysis today
IS - 3-4
ER -