Catalysts Combustion Of Binary Mixture On The Transition Metal Catalysts

Volatile organic compounds （VOCs） are known as harmful pollutants because of theirtoxic, malodorous, mutagenic and carcinogenic nature. Several different technologies havebeen developed for eliminating these troublesome substances, of which catalytic oxidationhas been identified one of the most promising techniques because it is a final disposal andenergy saving process.Organic exhaust emission from various industrial processes usually contains VOCsmixture and water vapor. It has greatly influences on the efficiency of catalytic oxidation ofVOCs. This work is mainly concerned with the study of the catalytic combustion of thebinary mixtures of VOCs on the prepared catalysts, and effects of relative humidity on thecatalytic activity of the catalysts.The effects of preparation methods on the cobalt based catalysts for toluene oxidationwere investigated. Results showed that the catalytic activity of the catalyst Co/cord-EGprepared by chemical reduction with ethylene glycol was much higher than that of thecatalyst Co/cord prepared by the conventional impregnation.The cobalt species were mainlypresented on the catalyst Co/cord-EG in the form of cobalt （II） oxide. The application of theEG reduction method favored the formation of smaller particles and higher dispersion of thecobalt species on the supports.The activities of the Mn-Ce baesd and Cr-Mn catalysts in the oxidation ofdichloromethane, ethyl acetate were investigated, which oxidized individually and in binarymixtures. And the total conversion temperature of the two-components mixture wasdetermined by the temperature at which the most difficult molecule was oxidized, in this casedichloroethane.The higher contents of ethyl acetate in the mixed gas, T90temperature of themixture is lower. One or both of the following reason might contributed to the acceleration ofthe reaction rate of the mixture gas decomposition:（i） the more difficult oxidized compoundsdichloroethane was decreased;（ii） Additional heat produced during the oxidation of theaddition of ethyl acetate.TPD analysis showed that ethyl acetate and trichloroethane feededsumminately can increased the adsorption of the two compounds on the catalyst surface.The effect of the water vapor to the brinary mixture oxidized on the CrMn_0.25/Al₂O₃catalyst were studied in the work.The activities were decreased when the humidity changed from0%to90%,and the decreasing scale was within6%. Results showed that the wetresistance performance of CrMn_0.25/Al₂O₃catalyst is good.Moreover; we found that theinhibition effect by the water vaper was reversible.TPD results showed that there is acompetitive adsorption among the VOCs and H2O, which might lead to an inhibition on theactivity of the catalyst. TPD analysis showed that the competed adsorption phenomenon werefound between H2O and VOCs molecules.In low temperatures,Water vapour made abigger influence on the adsorption of the binary mixtures over CrMn_0.25/Al₂O₃catalyst,but it hadlittle effect while in high temperatures. The reaction conditions on the activity of the catalystCrMn_0.25/Al₂O₃for brainy mixture oxidation were investigated.The CrMn_0.25/Al₂O₃.Thecatalyst could keep good activities during a large VOCs concentration and high space velocity,besides the stability of the catalyst present good.