Abstract

i

Acknowledgements

iv

List of Symbols and Abbreviations

v

1.

Introduction

1.1

The Fischer-Tropsch Process; History, Past and Future Prospects

1

1.2

The Spung Research Programme

3

1.3

Scope of the Current Investigation

4

2.

Literature Review

2.1

Cobalt; Chemical Properties and Catalytic Uses

6

2.2

The nature and Role of Carbon in CO Hydrogenation over Supported Cobalt Catalyst

9

2.3

Temperature Programmed Reduction (TPR)

2.3.1

Introduction

15

2.3.2

Reductive decomposition of Co(NO₃)₂6H₂O

15

2.3.3

The extreme situations, CO₃O₄ and CoAl₂O₄

16

2.3.4

The effect of the cobalt loading

18

2.3.5

The effect of the support

21

2.3.6

The effect of different pretreatment conditions

22

2.4

Fourier Transform Infrared (FTIR) Spectroscopy

2.4.1

Introduction

28

2.4.2

Carbon monoxide as a molecular probe

28

2.4.3

Assignment of Vibrational bands for CO on supported cobalt catalysts

30

2.4.4

Infrared ands for CO on CO₃O₄

36

2.4.5

Assignment of vibrational bands for CO on evaporated cobalt films

37

2.4.6

The effect of metal loading on the infrared spectra of supported cobalt catalysts

39

2.4.7

The Effect of hydrogen on adsorbed CO

40

2.4.8

Infrared bands of adsorbed species in the frequency region 3050-2700 and 1800-1200 cm^-1

42

2.5

CO Hydrogenation Activity and Selectivity

2.5.1

Introduction

44

2.5.2

Effect of metal loading and support on CO hydrogenation activity and selectivity

44

3.

Principles

3.1

The Fischer-Tropsch Synthesis

48

3.2

Temperature Programmed Reduction (TPR)

56

3.3

Infrared Spectroscopy

3.3.1

Theory

57

3.3.2

Optical principles

64

4.

Experimental and Procedures

4.1

Preparation of Catalysts

69

4.2

Temperature Programmed Reduction (TPR)

4.2.1

Apparatus

70

4.2.2

Procedure

70

4.3

Fourier Transform Infrared (FTIR) Spectroscopy

4.3.1

Preparation of pressed disks for IR measurements

72

4.3.2

High-Pressure infrared cells

73

4.3.3

Gas Flow System

75

4.3.4

Data acquisition

75

4.3.5

FTIR-procedure

75

4.4

Catalytic Activity Measurements

4.4.1

Apparatus and analytical equipment

78

4.4.2

Procedure

80

4.5

Gravimetric Studies

4.5.1

Gas Handling system and analytical equipment

80

4.5.2

Procedure

83

5.

Results and Discussion

Temperature Programmed Reduction Of Silica And Alumina Supported Cobalt Catalysts

5.1

Temperature Programmed Reduction of Silica and Alumina Supported Cobalt Catalysts

5.1.1

TPR-investigations of 0.82% Co/SiO₂ and 4.7% Co/SiO₂

85

5.1.2

TPR-investigations of 1% Co/y-Al₂)₃ and 4.6% Co/y-Al₂O₃

91

5.2

Fourier Transform Infrared (FTIR) Investigations

5.2.1

Introduction

97

5.2.2

A brief study of SiO2

98

5.2.3

Hydrogenation of CO over silica supported cobalt catalysts with different metal loading

5.2.3.1

100

5.2.3.2

CO spectral region for 4.7% Co/SiO₂ H₂/CO=2, P_tot=6 bar, T-473-573K

102

5.2.3.3

CO spectral region for 4.7% Co/SiO₂ H₂/CO=3, P_tot=6 bar, T=473-573K

104

5.2.3.4

CO spectral region for 4.7% Co/SiO2 H2/CO=3, Ptot=6r bar, T=473-573K

111

5.2.3.5

Estimation of the heat of adsorption of CO on 4.7% Co/SiO₂

129

5.2.3.6

Estimations of the amount of adsorbed CO on 4.7% Co/SiO₂ At reaction conditions

132

5.2.4
Part 2

Hydrogenation of CO over alumina supported Co Catalysts with Different metal loading

5.2.4.1

CO spectral region for 1% Co/y-Al₂O₃

135

5.2.4.2

CO spectral region for 4.6% Co/y-Al₂O₃ H₂/CO=_2,

144

5.2.5

Bands observed in the 3050-2800 cm^-1 spectral range over silica alone and silica supported Co Catalysts (0.82 and 4.7% Co/SiO₂) at different reaction conditions

159

5.2.6

Bands observed in the 3050-2800 cm^-1 spectral region over 4.6% Co/y-Al₂O₃ and pure alumina during CO hydrogenation

171

5.2.7

Discussion of the behavior and nature of the absorption bands observed in the frequency range 3050-2800 cm^-1

173

5.2.8

Bands observed in the 1800-1200 cm^-1 spectral range during CO hydrogenation over silica and alumina supported Co Catalysts

5.2.8.1

Introduction

181

5.2.8.2

4.7% Co/SiO₂

181

5.2.8.3

4.6% Co/y-Al₂O₃ NS Y-Al₂O₃

196

5.3

Catalytic Activity and Selectivity

5.3.1

Introduction

222

5.3.2

CO hydrogenation activity and selectivity of silica and alumina Supported cobalt catalysts

222

5.4

Gravimetric Investigations of 4.7% Co/SiO₂ and 4.6% Co/y-Al₂O₃ During CO Hydrogenation

5.4.1

Introduction

231

5.4.2

Gravimetric studies of 4.7% Co/SiO₂

232

5.4.3

Gravimetric studies of 4.6% Co/y-Al2O3

235

5.4.4

Discussion of the weight curves obtained during CO hydrogenation over silica, alumina, 4.6% Co/y-Al₂O₃ and 4.7% Co/SiO₂

242

6.

Summary and Conclusions

6.1

269

6.2

269

6.3

271

6.4

Gravimetry

272

7.

References

274

Appendices

284