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  • 1
    Electronic Resource
    Electronic Resource
    Preparation and characterization of Co/SiO2, Co-Mg/SiO2 and Mg-Co/SiO2 catalysts and their activity in CO hydrogenation (1995)
    Springer
    Topics in catalysis 2 (1995), S. 45-57 
    Details
    ISSN: 1572-9028
    Keywords: catalyst characterization ; cobalt ; magnesium ; silica support ; carbon monoxide hydrogenation ; synthesis gas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Co/SiO2, Mg-Co/SiO2 and Co-Mg/SiO2 catalysts were prepared from acetate, nitrate or carbonyl precursors. The catalysts were characterized by XRD, XPS, SIMS and TGA. The steady-state activity and product distribution of the catalysts were evaluated in synthesis gas reactions at 0.5 MPa and 235-290°C using 3 : 1 : 3 molar ratio of Ar : CO : H2. The activity in CO hydrogenation decreased in the precursor order Co2(CO)8〉Co(NO3)2〉 Co(CH3COO)2, and the probability of chain growth decreased in the precursor order Co(NO3)2〉Co2(CO)8〉Co(CH3COO)2. Alcohol yields were highest with Co2(CO)8, and lowest with Co(NO3)2, Magnesium promotion influenced the catalyst activity and decreased the CO2 formation, but the promotion effects were less profound than those of the precursor. Surface studies on partially magnesium covered cobalt foil model catalysts suggested that magnesium promotes CO dissociation and chain growth, neither of which were, however, observed in the supported catalysts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01491954
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of magnesium promoted Co/SiO2 catalysts (1995)
    Springer
    Catalysis letters 34 (1995), S. 75-84 
    Details
    ISSN: 1572-879X
    Keywords: catalyst characterization ; cobalt ; magnesium ; silica support ; carbon monoxide hydrogenation ; synthesis gas ; Fischer-Tropsch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Co/SiO2, Mg-Co/SiO2, and Co-Mg/SiO2 catalysts were prepared from nitrate precursors to get more insight into the effect of magnesium promotion on the cobalt catalyst. The desorption characteristics and reactivity of the catalysts towards synthesis gas were evaluated in a pulse micro reactor connected to an on-line quadrupole mass spectrometer. The presence of MgO both decreased the extent of reduction and increased the dispersion of cobalt. The reactivity results suggested that MgO promotion created new types of active sites, probably at the edge sites of cobalt and magnesium. The highest activity per metallic site available was obtained with a Mg: Co molar ratio of 1/2, i.e. with a high amount of edge sites. In accordance with previous results the formation of CO2 was clearly suppressed in the presence of MgO, and methanol was formed in trace amounts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00808324
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  • 3
    Electronic Resource
    Electronic Resource
    The long-term performance of Co/SiO2 catalysts in CO hydrogenation (1996)
    Springer
    Catalysis letters 42 (1996), S. 161-166 
    Details
    ISSN: 1572-879X
    Keywords: catalyst characterization ; cobalt ; silica support ; carbon monoxide hydrogenation ; synthesis gas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The activity in terms of conversion of carbon monoxide was determined for Co/SiO2 catalysts in CO hydrogenation over a reaction time of 120 h. The catalysts were prepared from nitrate (N) and carbonyl (CO) precursors. The conversion decreased rapidly during the first five hours, and thereafter moderately at a rate related to dispersion, i.e. the higher the dispersion the higher the rate of decrease. The active sites were blocked by wax and coke formed in the reaction, although some agglomeration of particles probably took place on the Co(CO)/SiO2 catalysts. More carbon was accumulated on Co(CO)/SiO2 than on Co(N)/SiO2 during the reaction suggesting a need for frequent regeneration. The reduction-oxidation-reduction treatments indicated, however, that the regenerability of the Co(CO)/SiO2 in terms of hydrogen uptake is poor, although the amounts adsorbed still remained higher than those for Co(N)/SiO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810682
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