Study On Low Temperature Catalytic Oxidation Of CO Over OMS-2 Catalyst Modified By Pd/Cu

Near-room temperature CO from industrial sources,highway tunnels and garages is detrimental to human health and the environment.Currently,low temperature CO catalytic oxidation technology is considered to be one of the most effective techniques for CO removal and the key of the technology is to develop highly efficient and stable catalysts.OMS-2 has mixed valence manganese ions(Mn²⁺,Mn³⁺,Mn⁴⁺),unique porous structure and is easy to release lattice oxygen.In recent years,OMS-2 has become the focus in the field of catalysis,but the activity of catalytic oxidation of CO is still not ideal over pure OMS-2.Therefore,in this paper,we adjusted the redox ability,the specific surface area and the content of lattice oxygen of the catalyst by loading precious metal Pd or doping transition metal Cu on OMS-2,thereby improving the low-temperature CO catalytic oxidation activity of the catalyst.The specific research contents were as follows:?1?A series of Pd/MnO_x?OMS-2,MnO₂,Mn₂O₃ and Mn₃O₄?catalysts were synthesized and applied to low temperature CO catalytic oxidation reaction,in which the Pd loading was only 0.3 wt.%.The activity test results showed that the catalytic activity of CO decreased in the order of Pd/OMS-2>Pd/MnO₂>Pd/Mn₂O₃?Pd/Mn₃O₄ and Pd/OMS-2 could completely convert CO to CO₂ at as low as 16°C.The H₂-TPR and BET characterization results indicated that the Pd/OMS-2 catalyst had higher reducibility and a larger specific surface area.In addition,XPS and in situ DRIFTS results indicated that a large amount of lattice oxygen was directly involved in the CO oxidation reaction,which was contributed to the excellent low temperature activity of Pd/OMS-2.However,the Pd/Mn₃O₄ catalyst only had a small amount of lattice oxygen.Moreover,CO was strongly adsorbed on the Pd sites,which inhibited the adsorption of oxygen,resulting in extremely low activity.?2?CuO/OMS-2 catalysts were prepared by doping method?PI?,impregnation method?IM?and solid phase milling method?GR?.The activity test results showed that the addition of transition metal Cu significantly improved the activity of CO oxidation on OMS-2 catalysts.The CuO-OMS-2-PI catalyst prepared by doping method could completely oxidize CO to CO₂ at room temperature,which was obviously better than the catalysts prepared by impregnation method and solid phase milling method.The excellent catalytic activity of CuO-OMS-2-PI was attributed to its large specific surface area and good redox ability.