Fischer-Tropsch synthesis: Moessbauer studies of pretreated ultrafine iron oxide catalysts. Partial quarterly progress report, April--June 1992

摘要

Moessbauer spectroscopy indicates that a 24 hour-pretreatment in CO at 260(degrees)C and 8 atm. in a tetralin solvent almost completely converts uftrafine iron oxide (about 3 nm) to iron carbide. However, pretreatment in hydrogen under the same conditions resulted in reduction of about 33% of the iron to metallic Fe; the remainder was Fe(sub 3)O(sub 4). Exposure of the CO pretreated catalyst to a 1:1 HDCO synthesis gas resulted in the gradual reoxidation of the carbides to Fe(sub 3)O(sub 4). During the first 2 hours of exposure of the H(sub 2) pretreated sample to synthesis gas,.the metallic Fe was converted to iron carbides. Further exposure of the H(sub 2) pretreatment sample to synthesis gas did not result in a composition change of the catalyst. Therefore, it is concluded that iron carbides with different oxidation characteristics were formed in these two cases.