Cu-exchanged Al-rich SSZ-13 zeolite from organotemplate-free synthesis as NH3-SCR catalyst: Effects of Na+ ions on the activity and hydrothermal stability
Cu-exchanged Al-rich SSZ-13 zeolite from organotemplate-free synthesis as NH3-SCR catalyst: Effects of Na+ ions on the activity and hydrothermal stability
复制标题
无有机模板合成的 Cu 交换富铝 SSZ-13 沸石作为 NH3-SCR 催化剂：Na 离子对活性和水热稳定性的影响
DOI：
10.1016/j.apcatb.2017.06.013
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发表时间：
2017-11-15
影响因子：
22.1
通讯作者：
Zhang, Weiping
中科院分区：
文献类型：
--
作者：
Zhao, Zhenchao;Yu, Rui;Zhang, Weiping
目前商业化的Cu-SSZ-13催化剂在NH3-SCR反应中存在低温活性低和成本高的问题。采用无模板剂法制备了Si/Al=4的富铝Cu交换SSZ-13催化剂，在150 ~ 650 ℃的宽温窗内，NO转化率均在85%以上，表现出上级的NH3-SCR性能。通过对富铝的Na-SSZ-13进行部分离子交换，制备了不同Na+含量的Cu-Na-SSZ-13催化剂，发现适量Na+含量的Cu-Na-SSZ-13催化剂既能提高低温活性，又能提高水热稳定性。Al-27和H-1 MAS NMR谱表明，残余的Na+可以稳定富铝SSZ-13分子筛中的骨架Al。UV-Vis-NIR和H-2-TPR光谱表明，Na+助阳离子促进了Cu 2+的还原，但过多的Na+助阳离子会导致CuOx的生成，进一步降低Cu-Na-SSZ-13催化剂的水热稳定性。优化的无有机模板剂Cu-Na-SSZ-13（2.7wt%Cu和1.7wt%Na）在750和800 ℃水热老化后在150-550 ℃下表现出与商业高硅Cu-SSZ-13催化剂几乎相同的NO转化率，并且显示出有希望的实际应用。(C)2017爱思唯尔B. V.保留所有权利。
The relatively low activity at lower temperatures and high cost of SSZ-13 zeolite from organotemplate synthesis are two of major problems of presently commercialized Cu-SSZ-13 catalysts for NH3-SCR reaction. Cu-exchanged Al-rich SSZ-13 catalysts with Si/Al=4 from organotemplate-free synthesis have been prepared, and show superior NH3-SCR performance with NO conversions above 85% at wide-temperature window ranging from 150 to 650 degrees C. Cu-Na-SSZ-13 catalysts with varied amount of residual Na+ were prepared by partial ion-exchange of as-prepared Al-rich Na-SSZ-13, and it's found that Cu-Na-SSZ-13 catalyst with moderate Na+ content can improve both the low-temperature activity and its hydrothermal stability. Al-27 and H-1 MAS NMR spectra indicate that residual Na+ can stabilize the framework Al in Al-rich SSZ-13 zeolite. UV-Vis-NIR and H-2-TPR spectra demonstrate that Na+ co-cations enhance the reducibility of Cu2+, whereas too much amount of Na+ may result in the formation of CuOx, during the hydrothermal treatment, and further decrease the hydrothermal stability of Cu-Na-SSZ-13 catalyst. The optimized organotemplate-free Cu-Na-SSZ-13 with 2.7 wt% Cu and 1.7 wt% Na exhibits almost the same NO conversions as the commercial high-silica Cu-SSZ-13 catalyst at 150-550 degrees C after 750 and 800 degrees C hydrothermal aging, and shows promising practical applications. (C) 2017 Elsevier B.V. All rights reserved.