改进钒基SCR脱硝催化剂的抗碱金属中毒性能

Improvement of alkali resistance of vanadium-titanic-based catalysts for selective catalytic reduction of NO_x by NH_3

以锐钛矿型二氧化钛和钛钨粉(5%WO3-TiO2)为载体,制备了系列钒和钨负载量不同的钒钛催化剂,考察碱金属和碱土金属(钾、钠和钙)对催化剂在氨选择性催化还原(NH3-SCR)氮氧化物反应中催化活性的影响。钾、钠和钙对钒钛催化剂的中毒影响大小顺序为钾>钠>钙。提高钒钛催化剂中钒的含量可显著提高催化剂的SCR活性和抗碱金属中毒性能,但高钒负载量(4.5%V2O5)造成催化剂氮气选择性明显下降,氧化亚氮生成显著增加。钨的添加有利于提高钒钛催化剂的低温活性和抗碱金属中毒性能,对氮气选择性无明显影响。

Vanadium-titanic-based catalysts were prepared from the anatase TiO2 and the anatase-tungsten powder containing 5% WO3.The effects of alkali and alkaline earth metals(K,Na and Ca) on the performance of vanadium-titanic-based catalysts in the selective catalytic reduction of NOx by ammonia(NH3-SCR) were studied.The degree of the poisoning effect for the alkali metals was shown as K > Na > Ca.The increase of vanadium loading in the catalyst can improve both the SCR activity and alkali resistance.However,high vanadium loading(4.5% V2O5) in the catalyst results in significantly decrease of N2 selectivity and increase in N2O production.The increase of tungsten loading can improve the low temperature activity and alkali resistance with little effect on N2 selectivity.