Alumina cluster-derived catalyst

Figure 5. Model for the alumina-supported, Cp2M2lr2(CO)io and CpMh 3-(CO)n cluster-derived catalysts.

H2 reduction. This may be due to interaction with Lewis acid sites on alumina. The IR spectra of cluster-derived platinum catalysts indicate bridged CO chemisorption, which is not seen with conventional Pt catalysts (Fig. 12). This is attributed to the morphological situation on the alumina-bound Pt clusters, in which coordinatively unsaturated faces are exposed. Moreover, it is interesting to find that the Pts-Ptis clusters did not undergo oxidative fragmentation in CO chemisorption even on the hydrated alumina and MgO (66a) unlike the case of Rh carbonyl cluster analog such as Rh4(CO)i2 and Rh,(CO)i5(Fig. 11). 

Heterogeneous, alumina-supported bimetallic catalysts derived from the sulfido clusters [Mo2Ni2S4Cp4] and [Mo2Ni2S4Cp2(CO)2] have been studied in CO metha-... 

The heterogeneous catalysts prepared from [MoIr3Cp(CO)n] (12) and [Mo2lr2Cp2(CO)io] (13) on alumina were studied for n-butane hydrogenolysis, a structure-sensitive reaction. From comparisons made with catalysts derived from homometallic clusters or their mixtures, it was deduced that the properties of the MMCD catalysts originated from bimetallic interactions maintained in the activated materials. 

EXAFS is a technique which has come into its own within the last five years [32-34] and has provided conclusive evidence which can be interpreted in terms of retention of the clustered state in active ruthenium catalysts derived from Ru3(CO)j 2 H4Ru4(C0)i2 active osmium catalysts derived from Os3(CO)32> H40s4(C0)] 2> 055(00) 3, supported on silica, alumina, and titania in our joint work with Hull University (Fig. 2) [35]. A particular advantage of EXAFS is that it is a technique which, in prospect, can be used iji situ to study working catalysts. 

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