Effect of CuSAPO-34 catalyst preparation method on NOx removal from diesel vehicle exhausts

Abstract

CuSAPO-34 samples prepared by hydrothermal synthesis (HS), pore-volume impregnation (PVI), and ion-exchange (IE) methods were characterized using X-ray diffraction, scanning electronic microscopy, atomic absorption spectroscopy, temperature-programmed reduction with hydrogen, X-ray absorption near-edge structure spectroscopy, X-ray photoelectron spectroscopy, and N 2 adsorption. The selective catalytic reduction (SCR) ability over CuSAPO-34 for NO x from a simulated diesel exhaust was investigated through C 3 H 6 -SCR and NH 3 -SCR, before and after aging of the CuSAPO-34 catalyst. The results indicated that the sample prepared by IE had significantly better activity compared with those prepared using HS and PVI, especially in C 3 H 6 -SCR at temperatures below 300 °C. The activity of CuSAPO-34 in NO SCR was affected by the preparation method as a result of changes in the specific area ( A BET ), pore-size distribution, and the valence state of the active component. The active component of the catalyst prepared by HS was mainly Cu 2+ , whereas those of samples prepared by IE and PVI were mainly Cu + . Aging treatment can destroy the structure of the catalyst, decrease its surface area, and reduce the number of active Cu components on the catalyst surface, leading to a visible decrease in catalytic activity. The CuSAPO-34 prepared using the PVI method had the smallest decrease in NO SCR activity after aging, showing that it had better anti-aging properties. 用一维CeO 2 纳米管替代非一维结构的商用CeO 2 , 用于负载Pd而制得的催化剂在空气气氛下高温煅烧过程中Pd纳米粒子的团聚受到明显抑制, 在选择性有氧氧化苯甲醇生成苯甲醛反应中, 所制CeO 2 纳米管负载的Pd催化剂表现出更高的催化活性. 可见, 一维金属氧化物材料有望用作载体以抑制贵金属纳米粒子的团聚, 从而提高其催化性能. CuSAPO-34 catalysts were prepared by hydrothermal synthesis, ion exchange, and pore-volume impregnation. The de-NO x activity of CuSAPO-34 strongly depended on the preparation method, and the sample prepared using ion exchange performed best in selective catalytic reduction in both NH 3 -SCR and C 3 H 6 -SCR.