Mn/Ba/Al2O3催化剂的NOx氧化-储存和耐硫性能

采用分步等体积浸渍法制备了Mn/Ba/Al2O3催化剂, 并用XRD和TPD等方法进行表征. 考察了催化剂在不同温度下NOx氧化-储存特性和NOx脱附行为. 结果表明, Mn/Ba/Al2O3催化剂具有较高的催化NO氧化活性和较大的NOx储存容量. BaMnO3是主要的活性组分；Mn能够催化NO的氧化反应, 且具有一定的NOx储存能力; Ba是主要的储存组分, 将NOx以硝酸盐的形式储存; 硝酸盐在300～600 ℃分解, 释放出NOx. Mn/Ba/Al2O3催化剂在800 ℃老化6 h后, NO氧化活性和NOx储存能力稍有下降. 低含量的SO2对催化剂的NO氧化活性和NOx储存能力没有明显影响; 高含量的SO2使催化剂的NO氧化活性降低, NOx储存量减小, 最终导致催化剂失活.

The NOx Oxidation-Storage and Tolerance of SO2 Poison of Mn/Ba/Al2O3 Catalyst

The performance of NOx oxidation-storage and desorption over Mn/Ba/Al2O3 catalyst were investigated at different temperatures. The catalysts were prepared by equal volume impregnation method and characterized by XRD and TPD. The results showed that Mn/Ba/Al2O3 catalyst had high catalytic activity for NO oxidation and large NOx storage capacity. BaMnO3 was the major active component. Mn could catalyze the oxidation of NO, having certain NOx storage capacity. Ba was the major storage component, NOx were stored with the formation of the nitrate that can be decomposed between 300~600 ℃ to release NOx. When Mn/Ba/Al2O3 was aged at 800 ℃ for 6 h, both the catalylic activity for NO oxidation and the NOx storage capacity were slightly decreased. The catalylic activity for NO oxidation and the NOx storage capacity were hardly affected by low concentration SO2. However, higher concentration SO2 decreased the catalylic activity for NO oxidation and the NOx storage capacity, leading to deactivation of the catalyst.