Preparation And Property Research Of The Copper-based Three-way Catalyst Doped With Nickel

With the rapid increase of the number of vehicles like motor vehicles and ships ,and thedevelopment of industry such as coal-fired plants, more and more harmful gases-forinstance,,carbon monoxide (CO), nitrogen oxides NO_x of which more than 90% is NO, andhydrocarbons (HC)- are emitted into the atmosphere. In order to save energy, lean-burn enginehas been developed greatly, but the engines will emit more NO. How to remove CO, NO andHC becomes an important concern at home and abroad. Therefore, developing anenvironmentally friendly catalys which can catalyze the conversion reaction of these harmfulgases effectively is a present research hotspot. In recent years, CeO₂-ZrO₂ solid solution iswidely developed as support in new catalysts. Currently the three-way catalyst usingCeO₂-ZrO₂ solid solution by loading precious metals like Pd, Pt and Rh as active componentshas good performance. However, precious metals are expensive scarce resources, thedevelopment of non-noble metal catalyst has aroused concern.This thesis was prepared with good three-way catalytic perforence of the new non-noblemetal catalyst which used Cu as active component.The Ce_1-λZr_λO₂ supports were obtained by coprecipitation method,and then load with Cuby equal volume impregnation to prepare Cu/Ce_1-λZr_λO₂ catalysts. By contrasting the activitiesof Cu/Ce-Zr-O catalysts with different Ce/Zr ratios, that was found Cu/Ce_0.6Zr_0.4O₂ have betterthree-way catalytic activity. The XRD pattern showed that Zr was injected in the crystal latticeof CeO₂ ,and Ce-Zr solid solution was formed. The addtion of Zr improves thermal stability ofCeO₂. The synergistic effect between Ce and Zr,enhances catalytic property of Cu/Ce_1-λZr_λO₂ .Ce-Zr solid solution was doped with Ni by coprecipitation to prepare the Ce_0.6Zr_0.4Ni_xO₂supports.Then the Cu/Ce_0.6Zr_0.4Ni_xO₂ catalysts were prepared by the supports loading with Cuby equal volume impregnation. By examining the influences of different Ni contents anddifferent Cu contents, The Cu_0.03/Ce_0.6Zr_0.4Ni_0.1O₂ catalyst was proved to have better catalyticactivity. From the XRD patterns ,it can be seen that Ce-Zr-Ni solid solution was formed solidsolution.This enhances the three-way catalytic activity of the catalyst further. Seen from theSEM pictures, Ni was added to make fine catalyst particles and prevent agglomeration. A series of Cu_0.03/Ce_0.6Zr_0.4Ni_0.1O₂/La-Al₂O₃ samples were prepared by using the mixtureof Ce_0.6Zr_0.4Ni0.1O₂ and La-Al₂O₃ as support and Cu as active component. The Ce_0.6Zr_0.4Ni₀₁O₂support was prepared by co-precipitation method. were maded by incipient-wetnessimpregnation of the simple mechanical mixture of Ce_1-λZr_λNi_xO₂ and La-Al₂O₃ with activecomponent Cu²⁺ aqueous solution. When the mass fraction of La-Al₂O₃ was 20%, the catalysthad the best catalytic activity. The light-off temperature of CO was less than 100℃.Thelight-off temperature of NO and C3H6 were 240℃and 250℃respectively. At temperature of300℃,CO and NO could be completely converted. C₃H₆ could be completely converted at 450℃.The catalyst by aging at 1000℃remained good activity. It indicated that the catalyst hadgood thermal stability. The XRD and SEM pictures showed the the addition of La-Al₂O₃catalyst particles can be further refined to increase the catalyst surface area,and then isconducive to improve the catalytic performance of catalysts.