Uniform distribution of copper and cobalt during the synthesis of SiMFI-5 from kanemite through solid-state transformation

Abstract

Two types of Cu- and Co-containing SiMFI samples were prepared through solid-state transformation (SST) from kanemite by adding metal nitrate directly to the synthesis mixture and by impregnation. Samples were characterized using XRD, ICP, TEM and TPR. XRD and TEM data show that both metals are highly dispersed inside the bulk zeolites for the SST samples. For samples containing more than 10 wt% cobalt, the characteristic metal oxide peaks were observed after calcination. In the case of CuSiMFI, narrow metal peaks are observed by XRD after reduction. The particle sizes are in the range 2–6 nm for the samples prepared by SST and exhibit a broad distribution range for those synthesized by the impregnation method. XRD shows that the samples have the SiMFI structure, independent of metal content. Despite the high metal content, the CoSiMFI and CuSiMFI samples prepared by SST show a high level of metal dispersion in the zeolite bulk.