Effect of ZrO₂ addition on de-NOx performance of Cu-ZSM-5 for SCR catalyst

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• 作者：Choong-Kil Seo^a ; Byungchul Choi^a ; ^{bcchoi@chonnam.ac.kr} ; Hwanam Kim^a ; Chun-Hwan Lee^b ; Chun-Beom Lee^b
• 关键词：Selective catalytic reduction (SCR) ; Cu-ZSM-5 ; ZrO2 ; HC poison
• 刊名：Chemical Engineering Journal
• 出版年：2012
• 期刊代码：16_13858947
• 类别：ce
• 出版时间：15 May, 2012
• 卷：191
• 期：Complete
• 页码：331-340
• 文件大小：2381 K

摘要

The aim of the present study is to investigate the de-NOx performance of a Cu-ZSM-5 catalyst to which ZrO₂ additives are added to improve the low-temperature activity and durability of the selective catalytic reduction (SCR) catalyst for diesel vehicles. The main experimental parameters are the amount of ZrO₂ added, hydrothermal aging temperature, type of hydrocarbon (HC) and concentration of sulfur (S). The results showed that the NOx conversion of the Cu-ZSM-5-ZrO₂ (2 wt%) catalyst was improved by 10-20%compared to that of the Cu-ZSM-5 or Fe-zeolite catalyst in the temperature range of 200-300 掳C, because the addition of an appropriate amount of ZrO₂ additive can improve the activation of the Cu-ZSM-5-ZrO₂ (2 wt%) catalyst by enhancing the acidity of the SCR catalyst. The Cu-ZSM-5-ZrO₂ (2 wt%) catalyst was the (most?) resistant against hydrothermal aging, (because the?) ZrO₂ additives can advance the activation of the Cu-ZSM-5 catalyst by promoting its thermal stability. Alkenes such as propylene (C₃H₆) containing a double bond in the reaction gases had a more negative effect on the de-NOx performance of the Cu-ZSM-5 catalysts than other hydrocarbons. The curve of the de-NOx performance of the Cu-ZSM-5 catalysts in the presence of C₃H₆ decreased rapidly in the range of 200-350 掳C and then increased again to form an M-shaped curve due to the blocking of the SCR reaction. Although the recovery rate of the de-NOx performance for Cu-ZSM-5-ZrO₂ (2 wt%) from sulfur poisoning was not reversible, it was higher than those of the Cu-ZSM-5-ZrO₂ (0 and 4 wt%) catalysts, because it contained the proper amount of ZrO₂. The proper amount of ZrO₂ for the Cu-ZSM-5 SCR catalyst was 2 wt%.