Effective Way to Control the Performance of a Ceria-Based DeNOx Catalyst with Improved Alkali Resistance: Acid鈥揃ase Adjusting

详细信息    查看全文

• 作者：Haiqiang Wang ; Shan Gao ; Feixiang Yu ; Yue Liu ; Xiaole Weng ; Zhongbiao Wu
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：July 9, 2015
• 年：2015
• 卷：119
• 期：27
• 页码：15077-15084
• 全文大小：422K
• ISSN：1932-7455

文摘

Compared with V₂O₅鈥揥O₃/TiO₂, the ceria catalyst supported on sulfated zirconia (referred to as CeSZ) shows a superior alkali resistance for selective catalytic reduction of NO in flue gases. It reveals an unexpected result that a moderate amount of potassium (normally considered as SCR poisons) could even enhance the activity of CeSZ catalyst. To investigate this exceptional phenomenon, we studied the surface acid鈥揵ase properties of CeSZ catalysts with different amounts of K and their influences on SCR performances. Although K resulted in a sharp decrease in Br酶nsted acid sites, the total acidity, especially strong acidity, barely changed when K/Ce was less than 0.4. It was proposed that a small amount of potassium could initially alter some Br酶nsted acid sites to Lewis ones, therefore retaining the majority of total acidity. Moreover, increased surface basicity due to K depositing led to an enhancement in NO chemisorption and oxidation, which is beneficial to the SCR process via the reaction of NO₂ and NO_x ad-species with adsorbed NH₃ species. This explains why the SCR catalytic activity was improved at lower temperature for CeSZ catalysts after K depositing. Therefore, the catalytic activity and reaction temperature window of CeSZ catalyst could be controlled by simply tuning the surface acid/base sites, which may give some inspiration to improve the catalytic activity and poisoning tolerance.