The synergistic effects between Ce and Cu in CuyCe1−yW5Ox catalysts for enhanced NH3-SCR of NOx and SO2 tolerance

Abstract

Manganese-based metal oxides are promising catalysts for the NH₃-SCR (selective catalytic reduction) of NO_x at low temperatures. However, manganese-based catalysts usually exhibit poor SO₂ and H₂O tolerance. In order to overcome the fatal shortcoming, non-manganese-based Cu_yCe_1−yW₅O_x catalysts (y = 0, 0.4, 0.5, 0.6, 1.0) are synthesized successfully by a standard co-precipitation method, and the catalytic performances of these catalysts are tested by the NH₃-SCR of NO_x. The results show that there are synergistic effects between Cu and Ce, which affect the Cu_yCe_1−yW₅O_x catalysts in many aspects, such as the specific surface area, the surface contents of Ce³⁺ and Cu²⁺, the reductive strength and the amount of weak and strong acid sites on the surface. Moreover, the synergistic effects also have an impact on the de-NO_x mechanism of Cu_yCe_1−yW₅O_x catalysts, and finally decide their catalytic performances. Among all the Cu_yCe_1−yW₅O_x catalysts, the Cu_0.5Ce_0.5W₅O_x catalyst shows the best catalytic de-NO_x performance and good tolerance to SO₂ and H₂O poisoning. This work may provide a suggestion for the design of non-manganese-based SCR catalysts with the desired de-NO_x performance and good SO₂ tolerance by making use of the synergistic effects between different metal oxides.