Neodymium promotion on the low-temperature hydrothermal stability of a Cu/SAPO-34 NH 3 -SCR monolith catalyst

Abstract

Abstract Nd modified Cu/SAPO-34 catalyst for selective catalytic reduction of NO x by NH 3 (NH 3 -SCR) is prepared by wet-impregnation method and the catalytic performance and low-temperature hydrothermal (LTH) stability are evaluated. The catalyst shows little effect on the fresh activity but presents excellent LTH resistance by the incorporation of Nd. After LTH treatment, the catalytic performance barely changed for CuNd/SAPO-34, while significantly degraded for Cu/SAPO-34 below 400 °C. Meanwhile, the NO x conversion at 200 °C for the aged catalyst is enhanced from 64% to 86% by adding Nd. In addition, the catalysts are characterized using N 2 sorption, XRD, SEM, DRIFTS, H 2 -TPR and XPS. The results reveal that the destruction of zeolite framework by the attack of vapor is evidently inhibited and the stability of copper species is also improved during LTH treatment by the introduction of Nd. Consequently, the LTH stability of CuNd/SAPO-34 is much better than that of Cu/SAPO-34.