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Regeneration of Potassium Poisoned Catalysts for the Selective Catalytic Reduction of NO with NH3

Category: Control Techniques and Strategy

Volume: 19 | Issue: 3 | Pages: 649-656
DOI: 10.4209/aaqr.2018.07.0273
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Shaojun Liu1,2,3, Peidong Ji1, Dong Ye1, Ruiyang Qu1, Chenghang Zheng1, Xiang Gao 1

  • 1 State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
  • 2 School of Energy and Power, Jiangsu University of Science and Technology, Zhenjiang 212003, China
  • 3 Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education of China, Chongqing University, Chongqing 400044, China

Highlights

The effect of K on SCR activity and the regeneration of catalyst were investigated.
Surface K species were removed in acid washing, and occupied acidic sites released.
Extra active components were added for CeO2 doping.
Poisoned catalysts were washed with H2SO4 solution and then doped with 5 wt.% CeO2.


Abstract

In this study, we investigated the effect of potassium on the activity and regeneration of potassium-poisoned SCR catalysts. With the addition of potassium species, the NO conversion rate of the catalysts continuously decreased. After washing the poisoned catalysts with an H2SO4 solution or doping them with CeO2, the activity of the catalysts was improved to different extents. Acid washing almost completely removed the surface potassium species, freeing acidic sites to adsorb NH3, but it also potentially removed some of the active components, such as vanadia. CeO2 doping, on the other hand, added active components. Combining these two methods, the poisoned catalysts were washed with an H2SO4 solution and then doped with 5 wt.% CeO2. It was found that the level of activity could be restored to that of a fresh catalyst, and a conversion rate of over 90% was observed for NO between 300°C and 450°C, as the added CeO2 compensated for the active components lost during SCR reactions. Consequently, the above hybrid method shows high potential for regenerating commercial SCR catalysts.

Keywords

Selective catalytic reduction Potassium Deactivation Regeneration Ceria


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