Pt/Al2O3蜂窝状催化剂上NO选择性催化还原反应动力学研究

采用多次涂层和浸渍法制备了蜂窝状Pt/Al2O3催化剂，并在高空速和大气体流量条件下对无梯度循环式反应器和积分反应器上催化剂的活性进行了比较。同时采用循环式反应器对动力学数据进行了测定。根据Langmuir-Hinshelwood模型和实验结果，推测了NO-C3H6-O2体系的SCR反应机理，并导出了NO和C3H6反应速率的数学表达式。据此所计算的理论模拟值能够与实验值很好地吻合。实验结果表明，氧气浓度对NO和C3H6的反应速率有明显的影响，二者均随着氧浓度c (O2)的增加达到峰值，再增加氧气浓度时，C3H6的反应速率r(C3H6)保持不变，而NO反应速率r (NO)却下降，而且下降的程度随着温度的升高而加剧。同时，随着氧气浓度增加，r (NO)达到最大值时的温度亦随之下降。

KINETICS OF THE REDUCTION OF NO BY C3H6 OVER A HONEYCOMB Pt/Al2O3 CATALYST

A honeycomb Pt/Al_2O_3 catalyst was prepared by multi-coating and wet-impregnation method. The catalytic performance and comparison of integral reactor and circulating reactor for selective catalytic reduction of NO over the catalyst have been studied. Based on Langmuir-Hinshelwood method and experimental results the mechanism of NO reduction by C_3H_6 was proposed. The mathematical expression for reaction rate of NO and C_3H_6 has also been established. The calculation result is consistent with the experimental data, and the result shows that the decomposition of NO on the catalyst surface is inhibited by superfluous O_2 at higher temperature.