INVESTIGATION OF MOS2 ON GAMMA-AL2O3 BY HREM WITH ATOMIC-RESOLUTION

High resolution electron microscopy and image calculations are perform ed on MoS2/gamma-Al2O3 based catalysts. It is shown that HREM allows a tomic imaging of the MoS2 particles on the alumina carrier. Restrictio ns with respect to atomic imaging are found from image simulations. Th e orientation of the slabs with respect to the electron beam is import ant. Whereas atomic imaging can be obtained in [100] and [110] directi ons, [001] oriented crystals will be invisible by HREM because of the way the slabs are mounted on the alumina support. The slabs are basal bounded. Since essentially single slabs are observed, it is suggested that a strong interaction exists between the slabs and the alumina sup port. EDX analysis shows that the MoS2 particles are sulfur deficient. We suggest that sulfur deficiency is present in the first sulfur laye r on the gamma-Al2O3 support. In specimens sulfided below 673 K an int ermediate phase is present, which is presumably an oxy-sulfide of moly bdenum.