Catalystic Combustion Of 1,2-dichloroethane On Transition Metal Oxides

1,2-dichloroethane (1,2-DCE) is one of typical chlorinated volatile organic compounds. Catalytic combustion is one of effective methods for the control of chlorinated volatile organic compounds. In this thesis, a series of transition metal oxides were synthesized and tested for catalytic combustion of 1,2-DCE. Catalytic activity, selectivity and stability of those materials on the combustion reaction were investigated.A series of MnO_x-CeO₂ catalysts were synthesized in oxidation precipitation method(OP), co-precipitation method(CP) and reverse microemulsions method(ME), and tested for catalytic combustion of 1,2-DCE. By changing the proportion of each component, catalytic activity of those materials were successfully improved. The results showed that MnO_x-CeO₂ mixed oxides by these three synthesis methods all had better performance than pure oxide in terms of catalytic activity, selectivity and stability. 0.5MnO_x-CeO₂ catalyst synthesized by oxidation precipitation had better reaction activity than the catalysts with the same metal ratio synthesized by co-precipitation method and reverse microemulsions method. The combustion temperature for the 50% of 1,2-DCE conversion (T50) over 0.5MnO_x-CeO₂-OP was 350℃, the combustion temperature (T90) was 425℃. The diffraction peaks of MnO₂ appeared for MnO_x-OP catalyst indicating more Mn4+ species on the surface of the catalyst prepared by the oxidation precipitation method than those of the catalysts prepared by co-precipitation method.MnO_x-CeO₂-OP supported on TiO₂, Al₂O₃, or ZrO₂ were also tested for catalytic combustion of 1,2-DCE. The results indicated those catalysts were better than unsupported MnO_x-CeO₂-OP catalysts. MnO_x-CeO₂-OP/TiO₂ showed the best activities in the catalytic combustion of 1,2-DCE among those catalysts.Cr₂O₃, TiO₂, CeO₂, ZrO₂ and MnO_x were tested for catalytic combustion of 1,2-DCE and the combustion temperature (T90) were 375℃, 385℃, 425℃, 440℃and 460℃. The results showed that TiO₂ synthesized by sol-gel method had the similar catalytic activity with the well known Cr₂O₃ catalyst. TiO₂ catalyst with good stability also had low selectivity of chlorinated organic by products and Cl2. Moreover, the 30% Cr₂O₃/TiO₂ with the best catalytic activity and selectivity was obtained by optimizing the Cr₂O₃ loading amount on TiO₂. The gas hourly space velocity (GHSV) of 10000h-1¹00000h-1 was also studied. When the GHSV was 10000h-1, the complete combustion temperature of 1,2-DCE over TiO₂ was 300℃.