Fischer-tropsch catalysts derived from surface confined [HnFeCo3(CO)12]n-1 (n = 0, 1)

R. S. Armstrong, T. Bell, A. F. Masters, M. A. Williams, A. L. Chaffee

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The preparation and characterization of species in which [HnFeCo3(CO)12]n-1 (n = 0, 1) are supported on partially dehydroxylated silica and on aminated silica are reported. [HFeCo3(CO)12], deposited onto aminated silica, yields the cluster anion, [FeCo3(CO)12]-, bound to the surface. However, when [HFeCo3(CO)12] is loaded onto partially dehydroxylated silica, deprotonation does not occur and the surface species is the cluster hydride. The cluster anion, as K+[FeCo3(CO)12]-, can be deposited onto both supports. The cluster anion, as PrNH3+[FeCo3(CO)12]-, can also be loaded onto partially dehydroxylated silica. All depositions occur without the formation of other IR detectable carbonyl-containing species and with the metal framework remaining intact. The supported clusters are precursors of active catalysts for the Fischer-Tropsch reaction at 1 atm. The catalysts, derived from the precursors by thermal activation under hydrogen, are active for at least 120 h. The order of activity is as follows: [HFeCo3(CO)12]/partially dehydroxylated silica < K+[FeCo3(CO)12]-/partially dehydroxylated silica ≈ K+[FeCo3(CO)12]-/aminated silica ≪ PrNH3+[FeCo3(CO)12]-/partially dehydroxylated silica ≈ [HFeCo3(CO)12]-/aminated silica. Only the catalysts derived from the last two precursors contain significant amounts of nitrogen. This is consistent with the formation of metal nitride phases in these catalysts and may correlate with their higher activity. Moreover, this formation of nitride phases occurs only when the nitrogen is in close association with the metal cluster. During the thermal activation of all the catalysts there was no loss of metal and the iron to cobalt ratio remained at 1:3. The effects of operational parameters on product distribution and CO conversion rates obtained with the catalyst produced from [HFeCo3(CO)12] deposited onto aminated silica also reported.

Original languageEnglish
Pages (from-to)2815-2822
Number of pages8
Issue number23
Publication statusPublished - 1990

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