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中南大学学报(自然科学版)

Journal of Central South University

第46卷    第6期    总第250期    2015年6月

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文章编号:1672-7207(2015)06-2382-09
商用SCR催化剂的钠中毒及再生
高凤雨,唐晓龙,易红宏,赵顺征,李东,马玎,张佟佟

(北京科技大学 土木与环境工程学院,北京,100083)

摘 要: 实验室模拟商用SCR催化剂(V2O5-WO3/TiO2)碱金属钠中毒,并通过水洗和0.5 mol/L H2SO4洗对失活催化剂进行再生。通过SEM,BET和XPS等方法对催化剂表面的理化性能进行分析,并探讨钒钛系催化剂的反应及失活机理。结果表明:较低负载量的Na2O会引发严重的催化剂中毒现象,通过水洗和酸洗再生可以使失活催化剂的表面活性得到不同程度的恢复,酸洗再生效果比水洗再生效果好;碱金属钠盐引起的催化剂物理中毒主要是盐颗粒的沉积和孔道的堵塞,但不是催化剂失活的主要原因,化学中毒主要是因为Na与催化剂表面的B酸性位上的V—OH发生反应,生成V—ONa,改变催化剂表面金属氧化物的化学环境,阻碍NO和NH3向催化剂内部的扩散;催化剂的脱硝活性与其表面的化学吸附氧量和表面活性中心上w(V4+)/w(V5+)的比有一定的正相关性。

 

关键字: 商用钒钛催化剂;钠中毒;再生;反应机理;失活机理

Sodium poisoning mechanism and regeneration of commercial De-NOx SCR catalysts
GAO Fengyu, TANG Xiaolong, YI Honghong, ZHAO Shunzheng, LI Dong, MA Ding, ZHANG Tongtong

Civil and Environmental Engineering School, University of Science and Technology Beijing, Beijing 100083, China

Abstract:Sodium poisoning of commercial De-NOx SCR catalysts (V2O5-WO3/TiO2) and the regeneration of deactivated catalysts by water and 0.5 mol/L H2SO4 were studied under simulated condition in laboratory. The physicochemical properties of catalysts were characterized by SEM, BET and XPS measurements, the reaction and deactivation mechanism of V2O5/TiO2 were also analyzed and discussed. The results indicate that catalysts are poisoned seriously with low-capacity Na2O, the catalytic activity of deactivated catalysts are recovered at varying degrees by washing with water and sulfuric acid, and the regeneration effect of washing with sulfuric acid is better than that of washing with water. Deposition of sodium salts particles and blocking of the pores and channels cause the physical poisoning of catalysts, and the main reason of chemical poisoning is attributed to the reaction of Na and V—OH to V—O—Na on the Br?nsted acid sites, which results in the changes of the chemical environment of metallic oxide on the surface of catalysts, thus blocking the spread of NO and NH3 to the inner of catalysts. The results also indicate that the denitration performance of SCR catalysts has certain positive correlation with the contents of chemical adsorbed oxygen and the ratio of w(V4+)/w(V5+) on the surface of catalysts.

 

Key words: commercial V2O5/TiO2 catalysts; sodium poisoning; regeneration; reaction mechanism; deactivated mechanism

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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