Diesel soot and NOx abatement: K/La2O3 catalyst stability
Diesel soot and NOx abatement: K/La2O3 catalyst stability
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DOI：
10.1016/j.apcatb.2010.08.031
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发表时间：
2010-11
影响因子：
22.1
通讯作者：
M. A. Peralta;M. Ulla;C. Querini
中科院分区：
文献类型：
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作者：
M. A. Peralta;M. Ulla;C. Querini
碳烟颗粒和氮氧化物是柴油机排放的主要污染物。本文对KOH/La2O_3催化剂的活性和稳定性进行了研究。该催化剂对NOx具有良好的吸附性能，可作为NOx捕集剂使用。此外，程序升温氧化分析表明，它对碳烟燃烧具有活性。采用FTIR、X射线衍射、CO2-TPD、CO2脉冲和BET等技术对催化剂进行了表征。催化剂的表面组成取决于H2O、CO2、NO和O2的相对分压。尽管表面组成不同，但在与真实柴油废气相似的操作条件下，催化活性保持相当稳定。高温处理，如800°C，特别是在水存在的情况下，会由于钾挥发而导致不可逆转的催化剂失活。凝结在催化剂上的水可以洗掉外表面的一小部分钾，导致活性下降。然而，当催化剂在400℃下处理时，钾从孔内扩散到外表面，从而恢复了碳烟燃烧的活性。
Soot particles and nitrogen oxides are the main pollutants emitted by a diesel engine. In this work, the activity and the stability of the KOH/La2O3catalyst are studied. This catalyst is able to adsorb NOx, which is a good property for the catalyst in order to be used as a NOxtrap. In addition, it is active for soot combustion as determined by temperature-programmed oxidation analyses. FTIR, XRD, CO2-TPD, Pulses of CO2, and BET techniques are used in order to characterize the catalysts. The catalytic surface composition depends upon the relative partial pressures of H2O, CO2, NO and O2. Despite the different surface compositions, the catalytic activity remains quite stable, under operation conditions similar to those of a real diesel exhaust. High temperature treatments, such as 800°C, and especially in the presence of water, leads to an irreversible catalyst deactivation due to potassium volatilization. The water condensed on the catalyst, could wash-out a fraction of the potassium from the outer surface, leading to a decrease in activity. However, when the catalyst is treated at 400°C, potassium diffuses from inside the pores to the external surface, thus recovering activity for soot combustion.