STRUCTURE OF CO AND CO OXIDE CLUSTERS IN MCM-41

The structural properties of Co/MCM-41 with pore diameters between 2.9 and 3.6 nm prepared by direct synthesis and impregnation were investi gated. For both preparation methods, the size of the metal particles d ecreased with the pore diameter. For Co/MCM-41 with the same pore diam eter we observed that the direct synthesis method led to significantly smaller metal clusters compared to the impregnation method. For all C o/MCM-41 samples constraints of the metal cluster sizes were observed, which are speculated to result from influences of the micro structure during the formation of the catalyst precursor. (C) 1998 Elsevier Sci ence B.V.