The poisoning effect of Na+ and Ca2+ ions doped on the V2O5/TiO2 catalysts for selective catalytic reduction of NO by NH3
The poisoning effect of Na+ and Ca2+ ions doped on the V2O5/TiO2 catalysts for selective catalytic reduction of NO by NH3
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DOI：
10.1016/j.apcatb.2009.10.022
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发表时间：
2010-02
影响因子：
22.1
通讯作者：
Fushun Tang;Bolian Xu;Hai-Wei Shi;J. Qiu;Yining Fan
中科院分区：
文献类型：
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作者：
Fushun Tang;Bolian Xu;Hai-Wei Shi;J. Qiu;Yining Fan
粉煤灰中碱金属和碱土金属盐的沉积导致V2 O 5/TiO 2催化剂失活是NH3选择性催化还原（SCR）NOx反应中的重要问题之一。本文研究了Na+和Ca ~（2+）离子掺杂对V_2O_5/TiO_2催化剂选择性催化还原NO反应的毒化作用。结果表明，Na+和Ca ~（2+）离子对V_2O_5/TiO_2催化剂有毒害作用，且Na+离子的毒害作用大于Ca ~（2+）离子。随着Na+/V摩尔比从0.00增加到0.20，NO在Na+-V2 O 5/TiO 2催化剂上的反应速率常数k从97.1急剧下降到35.0cm3g-1 s-1。相比之下，当Ca/V摩尔比低于0.05时，Ca 2 +-V2 O 5/TiO 2催化剂上的k几乎保持不变。进一步增加Ca/V摩尔比至0.20，导致k从101.8明显降低至46.3cm 3g − 1 s −1。Na+离子与分散的钒物种结合，中和了Brønsted酸中心，降低了它们的还原性。Ca ~（2+）对催化剂的B酸中心影响较小。Ca ~（2+）-V_2O_5/TiO_2催化剂上分散的钒物种比Na ~（2+）-V_2O_5/TiO_2催化剂具有更高的还原性。Na+和Ca 2+离子对V2 O 5/TiO 2催化剂的不同毒化作用不仅与催化剂的表面酸性有关，而且与催化剂的还原性有关。
Deactivation of the supported V2O5/TiO2catalysts due to deposition of alkali and alkaline earth metal salts in fly ashes is one of the most important problems in the selective catalytic reduction (SCR) of NOxby NH3. In this work, the poisoning effect of Na+and Ca2+ions doped on the V2O5/TiO2catalysts for selective catalytic reduction of NO by NH3has been studied. It has been shown that the Na+and Ca2+ions doped can poison the V2O5/TiO2catalyst and the Na+ions exhibit greater poisoning effect than Ca2+ions. The NO rate constant k on the Na+-V2O5/TiO2catalyst decreased very sharply from 97.1 to 35.0cm3g−1s−1with increasing Na/V molar ratio from 0.00 to 0.20. In comparison, k on the Ca2+-V2O5/TiO2catalyst remained almost unchanged when Ca/V molar ratio was below 0.05. Further increasing Ca/V molar ratio to 0.20 resulted in an obvious decrease of k from 101.8 to 46.3cm3g−1s−1. It was suggested that Na+ions combined strongly with dispersed vanadia species, neutralized the Brønsted acid sites and reduced their reducibility. In comparison, Ca2+ions slightly affected the Brønsted acid sites of catalyst. Besides, the dispersed vanadia species on the Ca2+-V2O5/TiO2catalyst had higher reducibility than Na+-V2O5/TiO2catalyst. The different poisoning effects of Na+and Ca2+ions doped on the V2O5/TiO2catalyst were correlated not only to the surface acidity but also to the reducibility of catalyst.