Title: The activity for the metathesis of propylene on Mo(CO)/sub 6//Al/sub 2/O/sub 3/
Abstract: The metathesis of propylene at 53/sup 0/C on molybdenum hexacarbonyl on alumina pretreated at various temperatures has > 99% selectivity to ethylene and 2-butenes. The activity of catalysts pretreated below 100/sup 0/C increased with increasing pulse number and was entirely due to adsorbed Mo(CO)/sub 3/ species. The catalysts could be activated similarly by several ethylene pulses. The highest conversion was obtained on the catalyst pretreated at 280/sup 0/C and having the mildly oxidized Mo(CO)/sub 2/O/sub 2/ composition. Exposure of the catalyst pretreated at 100/sup 0/C to trichloroethylene increased its initial activity by a factor of 90, probably by removal of two carbonyls from Mo(CO)/sub 3/. The reaction was poisoned by water vapor, and the use of fully hydroxylated alumina as support produced inactive catalysts. Molybdenum carbonyl on dehydroxylated alumina, activated at 500/sup 0/C, was about 100 times more active than the catalyst derived from partially hydroxylated alumina. The results suggested that zero- and hexavalent molybdenum were inactive, that molybdenum at a wide range of intermediate oxidation states is active, and that only a small fraction of the molybdenum surface (< 1%) is active. Graphs, tables, and 18 references.
Publication Year: 1978
Publication Date: 1978-05-01
Language: en
Type: article
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