Effect of potassium and copper promoters on reduction behavior of precipitated iron catalysts
Precipitated Fe catalysts were characterized using temperature-programmed methods, isothermal reduction, and X-ray photoelectron spectroscopy to study the influence of Cu and K promoters on reduction behavior and catalytic properties for Co hydrogenation. TPR results showed that of Fe increased with increasing Cu content up to {approximately}3 wt% Cu. The time required for Fe reduction at 300 C in either H{sub 2} or CO decreased with increasing Cu content. The presence of K influenced the reducibility of the precipitated Fe catalysts both with and without Cu. A possible blockage of nucleation sites by K may inhibit the reduction of Fe in H{sub 2}. However, the time required for Fe reduction in CO decreased in the presence of K. The inhibition effect of SiO{sub 2} and Al{sub 2}O{sub 3} supports on the reduction of Fe increased with increasing support content. XPS results showed differences in the surface composition of catalysts. The surfaces of H{sub 2}-reduced samples were largely covered by a layer of iron oxide; however, the surfaces of the CO-reduced samples possessed zero-valent iron. A marked enrichment of K was found on the surface of H{sub 2}-reduced samples compared to those of CO-reduced samples. No significant change in catalytic selectivity for CO hydrogenation at 250 C was observed in the presence of Cu promoter. However, significant increases in olefin/paraffin ratios and hydrocarbon product chain lengths were observed for the K-promoted Fe catalysts in the CO hydrogenation results. Lower percentages of methane formation and higher hydrocarbon chain lengths were observed for H{sub 2}-reduced Fe catalysts compared to those observed for CO-reduced catalysts.
- Research Organization:
- Texas A and M Univ., College Station, TX (USA)
- OSTI ID:
- 7035207
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
010408* -- Coal
Lignite
& Peat-- C1 Processes-- (1987-)
ALKALI METALS
ALKANES
ALKENES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
COBALT
CONTROL
ELECTRON SPECTROSCOPY
ELEMENTS
HYDROCARBONS
HYDROGENATION
INHIBITION
IRON
METALS
METHANATION
METHANE
MINERALS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
POTASSIUM
PROMOTERS
REDUCTION
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SPECTROSCOPY
SURFACE PROPERTIES
TEMPERATURE CONTROL
TRANSITION ELEMENTS
X-RAY SPECTROSCOPY
YIELDS