Study On Catalytic Combustion Of Organosulfur Compounds Waste Gas With Supported Catalysts

The mass production of chemicals and the treatment of waste water always produce the large emissions of organosulfur compounds waste gas,which is harmful to human being with irritating ordor even at low concentrations.The catalytic combustion is considered as an effective method to convert organosulfur compounds into SO2,CO2 and H2O.However,the normal noble metal catalysts are easily deactived in the presence of sufur species,thus it is difficult for normal noble metal catalysts to deal with waste gas containing organosulfur.Therefore,it is urgent to develop a high active catalyst with great sulfur tolerance.A series of monometallic or bimetallic catalysts prepared by wet impregnation method were tested in the catalytic combustion reaction of dimethyl disulfide(DMDS).The structures of catalysts were characterized and the relationship between the catalytic performance and the structure was investigated to screen out the most promising one which is suitable for catalytic combustion of DMDS.Firstly,a series of monometallic catalysts Cu/(Al2O3,CeO2,CeO2-Al2O3),(Cu,Fe,Zn,Mo,V,Pt,Pd)/CeO2-Al2O3 were prepared by wet impregnation method were tested in the catalytic combustion of DMDS.The results showed that the complete conversion temperature of Cu/CeO2-Al2O3 was 308?,better than that of Cu/Al2O3(335?)and Cu/CeO2(423?).The existence of CeO2 enhanced the redox properties and dispersion of CuO on the surface of catalyst,resulting in the better catalystic performance.Moreover,the DMDS conversion of the investigated transition monometallic catalysts followed a trend of Cu/>Fe/>Mo/>V/>Zn/CeO2-Al2O3,which was same to their redox properties according to TPR results.Noble catalysts showed the similar pattern.The corresponding activities were influenced by both redox properties and chemical natures of supported metals.A series of bimetallic catalysts(Cu-Mo,Cu-Fe,Cu-Zn,Cu-V,Cu-Pt,Cu-Pd)/CeO2-Al2O3 and Cu-Pt/(Al2O3,CeO2,CeO2-Al2O3)prepared by wet impregnation method were tested in the catalytic combustion of DMDS.The results showed that the DMDS conversion of the investigated bimetallic catalysts followed a trend of Cu-Pt/>Cu-Pd/>Cu-Mo/>Cu-Fe/>Cu-Zn/>Cu-V/CeO2-Al2O3 which was same to their redox properties except Cu-Mo/CeO2-Al2O3.The results showed that the complete conversion temperature of Cu/CeO2-Al2O3 was 262?,better than that of Cu-Pt/Al2O3(302?)and Cu/CeO2(399?).Because the Pt species of Cu-Pt/CeO2-Al2O3 were observed in the form of Pt0 which enhanced the redox properties and dispersion of CuO on the surface of catalyst more greatly than PtO.The existence of CeO2 also enhance the redox properties of CuO on the surface of catalyst.Therefore,Cu-Pt/CeO2-Al2O3,which exhibited the best activity among monometallic and bimetallic catalysts,is a promising catalyst in the catalytic combustion of DMDS.The research focused on the influence of prepared conditions and evaluation conditions of Cu-Pt/CeO2-Al2O3 in the catalytic combustion of DMDS conversion.The results showed that Cu-Pt/CeO-2-Al2O3 prepared when the pH of dipping solution was 5-7 and the loading of Cu was 5%(wt.)exhibited the highest DMDS conversion at 262?-550? among all catalysts under an atmosphere of 1000 ppm DMDS and 5%O2 and with the gas hourly space velocity of 50000 h-1.What's more,the long-term stability test(1000h)for Cu-Pt/CeO2-Al2O3 showed that the conversion of DMDS reminded about 100%with the gas hourly space velocity of 30000 h-1.