This study presents the catalytic performances of iron containing ZSM-5 zeolites, prepared by ion exchange or hydrothermal synthesis, in catalytic Fenton-like oxidation of Orange II in aqueous solution. The catalyst, ZSM-5 zeolite with Si/Al ratio of 42 loaded with iron by ion exchange, showed the highest activity. The decolorization of 99.7 percent, degradation of 87.0 percent and COD removal of 81.2 percent were achieved over this catalyst at an initial pH of 3.5. Incorporation of iron into ZSM-5 structure increased its catalytic activity. The hydrothermally prepared FeZSM-5 catalyst was more stable against leaching at low pH value due to the iron being in the framework.
In this study, Fenton-like degradation of Orange II in water was investigated over an FeZSM-5 zeolite catalyst prepared by ion exchange. A color removal of 99.99 % and a COD elimination of 55.0 % were achieved after a reaction time of 2h at 266.7 mM H2O2 at 323 K for 0.05 g/dm3 of Orange II solution at a pH around 7. Initial decolorization rate was described by an equation of -rAo = 6.4x103 e-30.7/RT COII,o CH2O2,o0.3 where R is in kJ/mol. No significant decay in decolorization efficiency of the used catalyst was observed.
The vapor-phase air oxidation of toluene to benzaldehyde over a Vz05 catalyst was investigated in an isothermal integral flow reactor a t atmospheric pressure between 350 and 480 "C. T h e effects of several variables, the feed ratio of oxygen to toluene, the reaction temperature, and the reciprocal of the space velocity, on the conversion and selectivity to benzaldehyde were determined. Nine different mechanisms were postulated and the rate expression TT = ( K 1 K g T 2 ) / ( K 1~T 2 + K2) fit the data best.
Catalytic wet air oxidation of oxalic acid in aqueous solution was investigated in a stirred reactor over a Pt (0.7% in wt)/Al2O3 catalyst at atmospheric pressure, in a concentration range of oxalic acid of 500-3000 ppm, and at a temperature range of 313-353 K. The conversions obtained after 5 h were 28.96 %, 45.98 % and 30.74 % for initial concentrations of 500, 1500, 3000 ppm, respectively. A rate equation of oxalic acid oxidation, in mol.h-1.g-1Pt was determined from measurements of initial rates, at different initial concentrations of oxalic acid, temperatures and catalyst mass loads. The activation energy for oxalic acid conversion was found to be 24.6 kJ mol-1.The heterogeneous catalyzed free-radical oxidation of oxalic acid was discussed.
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