Abstract

1

Table of Contents

iii

Acknowledgements

vii

1.

Introduction

1

1.1

Scientific and Technological Interest in Alkali Monolayers On Transition Metal Surfaces

 1

1.2

Overview of the thesis

3

1.3

Alkali Monolayers

4

1.4

Alkali Coadsoprtion Systems

6

1.5

CO Hydrogeneration Studies

8

2.

Experimental

10

2.1

Apparatus

11

2.2

Methods

14

2.3

Sample Preparation

19

2.4

Dosing

23

2.5

Overview of techniques to study promoter effects

24

2.5.1

Classical techniques

25

2.5.2

Modern ultrahigh vacuum (UHV) techniques

27

2.5.3

Modern “in situ” techniques

28

3.

Alkali Metal and alkali oxide adlayers

31

3.1

The Work Function

32

3.2

Pure Alkali monolayers

37

3.2.1

Thermodynamics:  AES and TDS behavior

37

3.2.2

Structure:  LEED studies

44

3.3.3

Electronic properties: UPS studies

44

3.3

Alkali Oxides: H₂O on Pt(111)

61

4.

Coadsorption Studies: Alkalis and Small Molecules on Metal Surfaces

71

4.1

Co adsorption on Potassium-dosed Pt(111)

72

4.1.1

CO bonding to metals

72

4.1.2

TDS Studies

78

4.1.3

Hreels Studies

86

4.1.4

UPS Studies

91

4.1.5

Discussion

98

4.2

Benzene adsorption on potassium-dosed Pt(111)

108

4.2.1

TDS Studies

108

4.2.2

UPS Studies

113

4.2.3

Discussion

119

4.3

No Adsorption on Potassium-dosed Pt(111)

124

4.3.1

TDS Studies

124

4.3.2

Discussion

125

4.4

PF3, CH3CN, andC4H8 adsorption studies

139

4.4.1

TDS Studies

139

4.4.2

Discussion

142

4.5

Literature review of alkali coadsorption studies

147

4.6

Conclusion

155

5.

The Use of Alkalis as Promoters:  CO Hydrogeneration Reactions

157

5.1

Introduction

157

5.2

Experimental

161

5.3

Results

162

5.4

Discussion

173

5.5

Literature Review

177

6.

References

182

Appendices

190

A.

Classification of additives

191

A.1

Introduction

191

A.2

Operational (Macroscopic) Categories of Catalyst Additives

192

A.3

Fundamental (Microscopic) Categories of Catalysts Additives

193

B.

Thermal Desorption Spectroscopy:  Practice and Theory

197

B.1

Theory of Rate Processes

198

B.2

The Thermal Desorption Equation

204

B.3

Aspects of the Thermal Desorption Experiment

212

B.4

Problems in Thermal Desorption Analysis

216

C.

Sulfur as an additive

220

C.1

Introduction

220

C.2

Experimental

221

C.3

Results

223

C.3.1

Chemisorbed Carbon Monoxide

223

C.3.2

Chemisorbed Bentene

226

C.4

Discussion

228

C.4.1

The Effect of Potassium

228

C.4.2

The Effect of Sulfur

229

D.

Review of related uses of alkali promoters in catalysis

232

D.1

Carbon Gasification

232

D.2

Ammonia Synthesis

238

E.

PET computer programming for surface science

240

E.1

Introduction

240

E.2

Computer Controlled Thermal Desorption Spectroscopy E-2

241

E.3

Computer Control for Photoelectron and Auger Spectroscopy

242

E.4

Auger/ESCA Display Program

243