The activity and selectivity of FeRe and FeIr catalysts with 100, 90, 50, 0 and 100, 50, 16.7, 0 atom-% iron content, respectively, and NiRe catalysts with 50 atom-% Ni content, all with 2 wt.-% total metal loading supported on silica, in the hydrogenation of carbon monoxide were investigated. The FeRe and FeIr catalysts showed a maximum in catalytic activity and their selectivity resembled more or less that observed on pure iron. Addition of potassium to the FeRe catalyst diminished the activity but C2+ and olefin selectivities were shifted toward that observed on iron. In contrast to the FeRe system, NiRe/SiO2 was reduced to a greater extent than Ni/SiO, but in both instances stabilization of the metal dispersion by rhenium was also observed. The reaction mechanism on the bimetallic catalysts largely depends on the type of the constituent atoms. On FeRe and NiRe catalysts inactive carbide formation is suppressed compared with that for pure nickel and iron. The main difference however, lies in the amount of the weakly bound hydrogen measured by temperature-programmed reduction, which is hardly altered in the Ni and NiRe system, but markedly increases when rhenium is added to iron. The FeIr catalysts resemble the NiRe samples.
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