| At present the commonly used catalysts for NH3-SCR are mainly molecular sieve and metal oxide catalysts.As the carrier of metal oxide catalyst,titania oxide exhibits prominent selective catalytic reduction ability,and ceria?CeO2?shows strong ability to store/release oxygen as an additive.It is beneficial to NH3-SCR reaction.There are few open reports about Cd-based catalyst using in NH3-SCR catalytic reaction.The transition metal oxide Cd-Ce-TiO2 catalysts were prepared by the method of coprecipitation.The catalysts were characterized by means of XRD,BET,SEM,TEM,Raman and UV-Vis DRS.And the catalytic activities of the catalysts for deNOx were evaluated by NH3-SCR reaction.The catalytic performances and physicochemical properties of these catalysts were investigated systematically.The structure of the catalysts will be remarkably influenced when the preparation conditions were changed during the coprecipitation process to prepare catalyst,such as drying temperature,aging of precipitation product and filtration,using the different precipitation solution.At room temperature,and using ammonia as precipitate,the production is amorphous and forms the mesoporous structure during coprecipitation preparation.The nanoparticles catalyst will be formed for Cd-Ce0.2-TiOx catalyst with the different metal Cd content,and some of them possess high specific surface area.Among all the catalysts,2% Cd-Ce0.2-TiOx catalyst exhibits the best NH3-SCR performance with a wide temperature window from 225 to 525 oC for NO conversion rate above 90%,and the high N2 selectivity reaches to 98 %.The metal ratio of Ce and Ti is changed in the catalyst.At high content of Ce,anatase structure disappeared in catalyst,but the amorphous oxide was formed.When the molar ratio Ce: Ti is 1:5,the mesoporous structure was formed in the catalyst,and an average aperture size is 10 nm.And the mesoporous structure of the catalysts are not produced for the other catalysts with the different Ce: Ti molar ratio. |
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