Fischer-Tropsch synthesis catalysed by cobalt-rhodium and cobalt-ruthenium carbonyl clusters on silica: Dissertation

Research output: ThesisDissertation

Abstract

A systematic study was made of the use of tetranuclear Co4-nRunHn(CO)12 (n = 0-4), Co2Ru2(CO)13 and Co4-nRhn(CO)12 (n = 0,1,2 or 4) clusters as catalyst precursors. Catalysts were characterized by temperature-programmed reduction and Fourier-transform infrared spectroscopy techniques, and their activity and selectivity in Fischer-Tropsch synthesis were determined, as well as the effect on their performance of reaction temperature, pretreatment atmosphere and method of preparation. Monometallic Co4/SiO2 and Ru4/SiO2 catalysts were very active and all rhodium-containing Co4-nRhn(CO)12/SiO2 catalysts were fairly weakly active in Fischer-Tropsch synthesis. Deactivation was associated with the bimetallic sites on cobalt-rhodium catalysts and with ruthenium on cobalt-ruthenium catalysts. The effect of temperature on the catalysts followed a characteristic trend: when the temperature increased, product selectivity shifted to lighter molecular mass compounds and selectivity for oxygenates mainly decreased. Per metal atom, refluxed catalysts tended to show higher activity in Fischer-Tropsch synthesis than did the corresponding impregnated catalysts. However, since the metal content of the refluxed catalysts was significantly lower than that of impregnated ones, the overall reaction rates over refluxed catalysts were slower. In the bimetallic catalysts, the interaction between cluster and support probably occurred between the rhodium species and silica, and between ruthenium species and silica, not between cobalt and silica. Evidently rhodium and ruthenium interact more strongly with silica than cobalt does.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • University of Eastern Finland
Supervisors/Advisors
  • Pakkanen, Tapani, Supervisor, External person
Award date15 Nov 1996
Place of PublicationEspoo
Publisher
Print ISBNs951-38-4948-1
Publication statusPublished - 1996
MoE publication typeG5 Doctoral dissertation (article)

Fingerprint

Rhodium
Fischer-Tropsch synthesis
Ruthenium
Cobalt
Silicon Dioxide
Catalysts
Catalyst activity
Metals
Temperature
Catalyst selectivity
Molecular mass
Catalyst supports
Reaction rates

Keywords

  • Fischer-Tropsch synthesis
  • clusters
  • cobalt
  • rhodium
  • ruthenium
  • carbonyl clusters
  • heterogenious catalysts
  • preparation
  • silica
  • spectroscopy
  • TPR
  • FT-IR

Cite this

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title = "Fischer-Tropsch synthesis catalysed by cobalt-rhodium and cobalt-ruthenium carbonyl clusters on silica: Dissertation",
abstract = "A systematic study was made of the use of tetranuclear Co4-nRunHn(CO)12 (n = 0-4), Co2Ru2(CO)13 and Co4-nRhn(CO)12 (n = 0,1,2 or 4) clusters as catalyst precursors. Catalysts were characterized by temperature-programmed reduction and Fourier-transform infrared spectroscopy techniques, and their activity and selectivity in Fischer-Tropsch synthesis were determined, as well as the effect on their performance of reaction temperature, pretreatment atmosphere and method of preparation. Monometallic Co4/SiO2 and Ru4/SiO2 catalysts were very active and all rhodium-containing Co4-nRhn(CO)12/SiO2 catalysts were fairly weakly active in Fischer-Tropsch synthesis. Deactivation was associated with the bimetallic sites on cobalt-rhodium catalysts and with ruthenium on cobalt-ruthenium catalysts. The effect of temperature on the catalysts followed a characteristic trend: when the temperature increased, product selectivity shifted to lighter molecular mass compounds and selectivity for oxygenates mainly decreased. Per metal atom, refluxed catalysts tended to show higher activity in Fischer-Tropsch synthesis than did the corresponding impregnated catalysts. However, since the metal content of the refluxed catalysts was significantly lower than that of impregnated ones, the overall reaction rates over refluxed catalysts were slower. In the bimetallic catalysts, the interaction between cluster and support probably occurred between the rhodium species and silica, and between ruthenium species and silica, not between cobalt and silica. Evidently rhodium and ruthenium interact more strongly with silica than cobalt does.",
keywords = "Fischer-Tropsch synthesis, clusters, cobalt, rhodium, ruthenium, carbonyl clusters, heterogenious catalysts, preparation, silica, spectroscopy, TPR, FT-IR",
author = "Jari Kiviaho",
note = "Project code: KET2415",
year = "1996",
language = "English",
isbn = "951-38-4948-1",
series = "VTT Publications",
publisher = "VTT Technical Research Centre of Finland",
number = "290",
address = "Finland",
school = "University of Eastern Finland",

}

Fischer-Tropsch synthesis catalysed by cobalt-rhodium and cobalt-ruthenium carbonyl clusters on silica : Dissertation. / Kiviaho, Jari.

Espoo : VTT Technical Research Centre of Finland, 1996. 36 p.

Research output: ThesisDissertation

TY - THES

T1 - Fischer-Tropsch synthesis catalysed by cobalt-rhodium and cobalt-ruthenium carbonyl clusters on silica

T2 - Dissertation

AU - Kiviaho, Jari

N1 - Project code: KET2415

PY - 1996

Y1 - 1996

N2 - A systematic study was made of the use of tetranuclear Co4-nRunHn(CO)12 (n = 0-4), Co2Ru2(CO)13 and Co4-nRhn(CO)12 (n = 0,1,2 or 4) clusters as catalyst precursors. Catalysts were characterized by temperature-programmed reduction and Fourier-transform infrared spectroscopy techniques, and their activity and selectivity in Fischer-Tropsch synthesis were determined, as well as the effect on their performance of reaction temperature, pretreatment atmosphere and method of preparation. Monometallic Co4/SiO2 and Ru4/SiO2 catalysts were very active and all rhodium-containing Co4-nRhn(CO)12/SiO2 catalysts were fairly weakly active in Fischer-Tropsch synthesis. Deactivation was associated with the bimetallic sites on cobalt-rhodium catalysts and with ruthenium on cobalt-ruthenium catalysts. The effect of temperature on the catalysts followed a characteristic trend: when the temperature increased, product selectivity shifted to lighter molecular mass compounds and selectivity for oxygenates mainly decreased. Per metal atom, refluxed catalysts tended to show higher activity in Fischer-Tropsch synthesis than did the corresponding impregnated catalysts. However, since the metal content of the refluxed catalysts was significantly lower than that of impregnated ones, the overall reaction rates over refluxed catalysts were slower. In the bimetallic catalysts, the interaction between cluster and support probably occurred between the rhodium species and silica, and between ruthenium species and silica, not between cobalt and silica. Evidently rhodium and ruthenium interact more strongly with silica than cobalt does.

AB - A systematic study was made of the use of tetranuclear Co4-nRunHn(CO)12 (n = 0-4), Co2Ru2(CO)13 and Co4-nRhn(CO)12 (n = 0,1,2 or 4) clusters as catalyst precursors. Catalysts were characterized by temperature-programmed reduction and Fourier-transform infrared spectroscopy techniques, and their activity and selectivity in Fischer-Tropsch synthesis were determined, as well as the effect on their performance of reaction temperature, pretreatment atmosphere and method of preparation. Monometallic Co4/SiO2 and Ru4/SiO2 catalysts were very active and all rhodium-containing Co4-nRhn(CO)12/SiO2 catalysts were fairly weakly active in Fischer-Tropsch synthesis. Deactivation was associated with the bimetallic sites on cobalt-rhodium catalysts and with ruthenium on cobalt-ruthenium catalysts. The effect of temperature on the catalysts followed a characteristic trend: when the temperature increased, product selectivity shifted to lighter molecular mass compounds and selectivity for oxygenates mainly decreased. Per metal atom, refluxed catalysts tended to show higher activity in Fischer-Tropsch synthesis than did the corresponding impregnated catalysts. However, since the metal content of the refluxed catalysts was significantly lower than that of impregnated ones, the overall reaction rates over refluxed catalysts were slower. In the bimetallic catalysts, the interaction between cluster and support probably occurred between the rhodium species and silica, and between ruthenium species and silica, not between cobalt and silica. Evidently rhodium and ruthenium interact more strongly with silica than cobalt does.

KW - Fischer-Tropsch synthesis

KW - clusters

KW - cobalt

KW - rhodium

KW - ruthenium

KW - carbonyl clusters

KW - heterogenious catalysts

KW - preparation

KW - silica

KW - spectroscopy

KW - TPR

KW - FT-IR

M3 - Dissertation

SN - 951-38-4948-1

T3 - VTT Publications

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -