NUMERICAL SIMULATION OF EFFECTS OF WALL THICKNESS AND CELL DENSITY ON THE THREE-WAY CATALYTIC CONVERTER PERFORMANCE

The transient symmetric mathematical model is established, and the effects of the wall thickness and cell density on the performance of a three-way catalytic converter are studied using numerical modeling. The conclusions show that the light-off time and the pressure drop through a converter are decreased, and the conversion efficiency during the warm-up period keeps almost invariant with reduction of the wall thickness of substrates, and that the pressure drop through a converter and a conversion efficiency during the warm-up state increases, and the light-off time almost keeps invariant when increasing cell density of substrates. Therefore, future catalytic converters should develop in the direction of thin wall thickness and high cell density substrates simultaneously.

Fe203-CeO2-Bi203/y-AI203 catalyst in the catalytic wet air oxidation （CWAO） of cationic red GTL under mild reaction conditions

The Fe203-CeO2-Bi203/-A1203 catalyst, a novel environmental-friendly material, was used to investigate the catalytic wet air oxidation （CWAO） of cationic red GTL under mild operating conditions in a batch reactor. The catalyst was prepared by wet impregnation, and characterized by special surface area （BET measurement）, X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS）. The Fe203-CeO2-]]i203/qt-A1203 catalyst exhibited good catalytic activity and stability in the CWAO under atmosphere pressure. The effect of the reaction conditions （catalyst loading, degradation temperature, solution concentration and initial solution pH value） was studied. The result showed that the decolorization efficiency of cationic red GTL was improved with increasing the initial solution pH value and the degradation temperature. The apparent activation energy for the reaction was 79 kJ. mo1-1. Hydroperoxy radicals （HO2.） and superoxide radicals （O2-） appeared as the main reactive species upon the CWAO of cationic red GTL.

Efficient degradation of Rhodamine B by magnetically recoverable Fe_(3)O_(4)-modified ternary CoFeCu-layered double hydroxides via activating peroxymonosulfate

Environment-friendly nano-catalysts capable of activating peroxymonosulfate(PMS)have received increasing attention recently.Nevertheless,traditional nano-catalysts are generally well dispersed and difficult to be separated from reaction system,so it is particularly important to develop nano-catalysts with both good catalytic activity and excellent recycling efficiency.In this work,magnetically recoverable Fe_(3)O_(4)-modified ternary CoFeCu-layered double hydroxides(Fe_(3)O_(4)/CoFeCu-LDHs)was prepared by a simple co-precipitation method and initially applied to activate PMS for the degradation of Rhodamine B(Rh B).X-ray diffraction(XRD),fourier transform infrared spectrometer(FT-IR),scanning electron microscope(SEM),transmission electron microscopy(TEM),Brunauer-Emmett-Teller method(BET),and vibrating sample magnetometer(VSM)were applied to characterize morphology,structure,specific surface area and magnetism.In addition,the effects of several key parameters were evaluated.The Fe_(3)O_(4)/CoFeCu-LDHs exhibited high catalytic activity,and Rh B degradation efficiency could reach 100%within 20 min by adding 0.2 g/L of catalyst and 1 mmol/L of PMS into 50 mg/L of Rh B solution under a wide pH condition(3.0-7.0).Notably,the Fe_(3)O_(4)/CoFeCu-LDHs showed good super-paramagnetism and excellent stability,which could be effectively and quickly recovered under magnetic condition,and the degradation efficiency after ten cycles could still maintain 98.95%.Both radicals quenching tests and electron spin resonance(ESR)identified both HO·and SO_(4)^(·-) were involved and SO_(4)^(·-) played a dominant role on the RhB degradation.Finally,the chemical states of the sample’s surface elements were measured by X-ray photoelectron spectroscopy(XPS),and the possible activation mechanism in Fe_(3)O_(4)/CoFeCu-LDHs/PMS system was proposed according to comprehensive analysis.