Controlled Synthesis Of Ce-based Catalytic Materials And Their Catalytic Combustion Of Chlorobenzene

Chlorinated volatile organic compounds?CVOCs?are a class of high toxic atmospheric pollutants with high stability.Therefore,it is urgent to develop an efficient technology to eliminate CVOCs from the environment.Among the existing techniques,catalytic combustion of CVOCs has important significance to control air pollution efficiently.For catalytic combustion,the most difficult task is how to develop a kind of high-efficiency and low-temperature catalysts.The present study has shown that ceria-based materials have high oxygen storage capacity to release and uptake oxygen,manganese oxides have excellent oxygen storage ability and outstanding redox properties.Consequently,we mainly discuss MnO_x/CeO₂ catalysts with different ceria morphology in this work.The Chlorobenzene was used as a model of CVOCs to demonstrate the activity of the prepared Ce-based catalysts.The specific work has been done as following:1.Nanosheets CeO₂ were synthesized through a simple aqueous phase precipitation method with NH₄HCO₃ as the precipitant.An incipient impregnation method was utilized to prepared a series of MnO_x/CeO₂ with different manganese contents.The effects of Mn content of MnO_x/CeO₂ catalysts on the catalytic properties for CB combustion was investigated.Similarly,Fe/Ce?0.50?,Co/Ce?0.50?,Ni/Ce?0.50?catalysts were synthesized as the contrast sample.MnO_x/CeO₂ nanoparticles catalysts was prepared using CeO₂nanoparticles as the carrier,donated as Mn/Ce-NPs.The catalytic tests result show that the nanosheets MnO_x/CeO₂ has higher catalytic catalytic activity than Mn/Ce-NP.Among Fe/Ce?0.50?,Co/Ce?0.50?,Ni/Ce?0.50?and Mn/Ce?0.50?catalysts,the Mn/Ce?0.50?catalysts showed the best activity.This result mainly attributable to the amount of adsorbed oxygen species and the good dispersion of surface manganese species.Nanosheets MnO_x/CeO₂catalysts with different Mn contents showed different activities when catalytic combustion of CB.And the Mn/Ce?0.50?catalysts showed the best activity.In addition,XPS result indicated that high valence state Mn⁴⁺is help for oxidation reaction.2.Leaf-like CeO₂ nanosheets with about 50 nm thickness have been successfully synthesized through a facile hydrothermal technique with NH₄HCO₃ as the precipitants and ethylenediamine as complexant.The morphology of Ce?OH?CO₃ precursor was used to control the structure of CeO₂.Uniform and independent leaf-like CeO₂ structures were obtained.Effect of the reaction time and the amount of ethylenediamine were investigated systematically.An incipient impregnation method was utilized to prepared a series of MnO_x/CeO₂ with different manganese contents.And the activity of catalytic combustion of chlorobenzene?CB?was used to evaluated the activity of as-synthesized catalysts.MnO_x/CeO₂ catalysts with different Mn contents showed different activity when catalytic combustion of CB.And the Mn/Ce?0.50?catalysts showed the best activity.The studies of the MnO_x/CeO₂ template showed that this kind of CeO₂ is beneficial to the dispersion of MnO_x on CeO₂ surface and the doping of Mn can increase the concentration of oxygen vacancy on the surface of catalysts.In addition,XPS result indicated thatO_ads,Ce³⁺and Mn⁴⁺are helpful for oxidation reaction.Through the activity and stability test results,we can indicate that the doping of Mn not only can increase the activity but also can enhance the stability.3.Hollow core-shell nanorods structure CeO₂@MnO_x and hollow core-shell triangle structure CeO₂@MnO_x were synthesized through interfacial oxidation-reduction reaction.The activity of catalytic combustion of chlorobenzene?CB?was used to evaluated the activity of as-synthesized catalysts and all kind structure of CeO₂@MnO_x catalysts showed good catalytic activity.This kind synthesized method can effectively prevent nano-particles aggregation on the surface of CeO₂ carrier.