Catalytic wet air oxidation of phenol using CeO2 as the catalyst. Kinetic study and mechanism development.
Using a CeO2 catalyst prepared from CeCl3.7H2O under high thermal impact, the catalytic wet air oxidation (CWAO) of phenol was effectively implemented. With initial phenol concentrations of between (400 and 2500) mg/L, and at a temperature of 160 degrees C, the rate of phenol conversion increased with increased catalyst loading (0.2g/L-1.0g/L) and oxygen pressure (0.5 MPa-1.5 MPa). Even at an initial concentration of 2500 mg/L, conversion of phenol was as high as 95% after 3 h reaction. The effect of phenol concentration, catalyst loading, and oxygen pressure on the initial rate of phenol conversion was evaluated in a kinetic study. The initial rate equation derived from kinetic study is: Ro=k1 x [Ph]1.3-1.4 x W0.5-0.6 x PO2(0.9-1.1), where k1 is a rate constant, and [Ph], W and PO2 refer to phenol concentration, catalyst loading and oxygen pressure, respectively. A free-radical involved reaction mechanism was proposed and an initial rate expression based on this mechanism was derived: Ro = k2 x [Ph]1.5 x W0.5, where k2 is also a rate constant. Fitting of experimental data with the theoretically derived initial rate equation resulted in good correlation: the coefficient is greater than 0.99.
Chang
Dong-Jang
DJ
Department of Environmental Engineering and Health, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan.
Lin
Shiow-Shyung
SS
Chen
Chun-Liang
CL
Wang
Shu-Pin
SP
Ho
Wei-Lun
WL
D002384:Catalysis; D002563:Cerium / Q000737:chemistry*; D004202:Disinfectants / Q000737:chemistry*; D004787:Environmental Pollution / Q000517:prevention & control; D007700:Kinetics; D010084:Oxidation-Reduction; D019800:Phenol / Q000737:chemistry*
D004202:Disinfectants; D002563:Cerium; D019800:Phenol; C030583:ceric oxide