Evaluation of alkali- impregnated honeycomb catalysts for NOx reduction in the SCR-process

by Johansson, Sofia

Abstract (Summary)
Samples of SCR catalysts were impregnated with the following alkali salts; KCl, K2SO4 and ZnCl2 at two different concentrations in a wet impregnation method. The activities of the six samples were measured in a test reactor and at different temperatures between 250-350 ºC. Compared to fresh catalyst, the impregnated samples all had lower activity. It seems like KCl is the most poisoning salt, depending on the lowest value of the activity. The experimental results are expected as compared to earlier articles, which reports that all alkali salts has deactivating effects on a catalyst and that KCl is among the most poisoning ones. By making a cross-section SEM analysis, the penetration of the metals at different depths in to the catalyst material wall was evaluated. An ICP-AES analysis was carried out in order to see the concentration of K and Zn of the test samples. Finally, the pore diameter and active surface was measured by BET method. Since the values of the active surface didn’t change compared to a fresh catalyst and the pore diameter was only slightly decreased we can suppose that the alkali salts deactivates the catalyst by coating of the catalyst pore structure and not as a pore blocking.
Bibliographical Information:


School:Växjö universitet

School Location:Sweden

Source Type:Master's Thesis

Keywords:scr kcl k2so4 zncl2 wet impregnation catalyst deactivating activity


Date of Publication:03/01/2007

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