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A New Approach to the Mechanism of Fischer–Tropsch Syntheses Arising from Gas Phase NMR and Mass Spectrometry
Author(s) -
Bordet Alexis,
Lacroix LiseMarie,
Soulantica Katerina,
Chaudret Bruno
Publication year - 2016
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201600245
Subject(s) - dispersity , fischer–tropsch process , chemistry , carbide , mass spectrometry , syngas , nanoparticle , carbon fibers , desorption , yield (engineering) , reaction mechanism , analytical chemistry (journal) , organic chemistry , materials science , catalysis , nanotechnology , adsorption , chromatography , selectivity , composite number , metallurgy , composite material
Abstract We used 13 CO labeling to show that gas‐phase NMR spectroscopy and mass spectrometry are simple tools for mechanistic investigations of the Fischer–Tropsch (FT) reaction. Thus, monodisperse Fe nanoparticles (NPs) react with syngas to form monodisperse iron carbide (FeC x ) NPs. As expected, the heating of 13 C‐labeled monodisperse FeC x NPs under H 2 results in the desorption of the carbide carbons as 13 CH 4 and, interestingly, restores the initial Fe NPs in terms of size and dispersity. The Fe 13 C x NPs catalyze the hydrogenation of 12 CO at 210 °C to yield only 12 C‐labeled FT products, which evidences the absence of the incorporation of FeC x carbon atoms in the products. In addition, this approach shows for the first time that the formation of 13 CH 4 at 250 °C does not result from direct carbide hydrogenation but from an intermediate step that involves a reaction between Fe 13 C x and H 2 O to give 13 CO 2 , which is subsequently hydrogenated. These results rule out the involvement of FeC x carbon atoms in the chain growth process under our conditions.