title: Photocatalytic degradation of gaseous benzene over TiO2/Sr2CeO4: kinetic model and degradation mechanisms.
abstract: Photocatalytic oxidation of benzene in air was carried out over TiO2/Sr2CeO4 catalysts. The prepared photocatalyst was characterized by SBET, UV-vis diffuse reflectance and XPS. TiO2/Sr2CeO4 absorbs much more visible light than TiO2 in the visible light region. The XPS spectrum shows that the binding energy value of Ti 2p3/2 transfers to a lower value. The main purpose was to investigate the kinetic model and degradation mechanisms. The kinetic data matched well with the Langmuir-Hinshelwood (L-H) kinetic model with the limiting rate constant and the adsorption constant in this case were 0.0064 mg l-1 min-1 and 9.2078 l mg-1, respectively. No gas-phase intermediates were detected by direct GC/FID analysis under the conditions despite the high benzene concentration. Ethyl acetate and (3-methyl-oxiran-2-yl)-methanol were two major identified intermediates which were accompanied by butylated hydroxytoluene, 2,6-bis(1,1-dimethylethyl)-4,4-dimethylycyclohe, 2,5-cyclohexadiene-1,4,dione,2,6-bis(1,1-dim). It is plausible that at least one of these less-reactive intermediates caused the deactivation of the photocatalyst. Finally, the photocatalytic oxidation mechanisms were speculated.
authors.affiliation: College of Chemistry, Sichuan University, Sichuan 610064, PR China. zhongjunbo@sohu.com
authors.forename: Junbo
authors.initials: J
authors.lastname: Zhong
authors.forename: Jianli
authors.initials: J
authors.lastname: Wang
authors.forename: Lin
authors.initials: L
authors.lastname: Tao
authors.forename: Maochu
authors.initials: M
authors.lastname: Gong
authors.forename: Liu
authors.initials: L
authors.lastname: Zhimin
authors.forename: Yaoqiang
authors.initials: Y
authors.lastname: Chen
mesh_terms: D001554:Benzene / Q000737:chemistry*; D002384:Catalysis; D005740:Gases / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D010782:Photolysis; D014025:Titanium / Q000737:chemistry*
chemical_list: D005740:Gases; D010087:Oxides; C518956:strontium cerium(IV) oxide; C009495:titanium dioxide; D014025:Titanium; D001554:Benzene