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Transient-Kinetic Study of Nickel-Catalyzed Methanation: Final Report - August 31, 1986

Paul Biloen
Yee Soong

University of Pittsburgh

Part 1 (Pages 1 - 128, 3.33MB)
Part 2 (Pages 129 - 253, 3.53MB)

Table of Contents

Abstract

iii
List of Figures x
List of Tables xvii
1.0 Introduction 1
 

1.1

 General Introduction 1

1.2

 Reaction Mechanisms 2

1.3

 Isotopic Transient Methods 8
1.4 Nature of Surface Carbon 11
1.5 Nature of Fractional Coverage of Reaction Intermediates and Their Reactivity 12
1.6 Structure Sensitive 16
1.7 Catalyst Aging 19
1.8 H/D Isotope Effect 21
1.9 H2 and CO Adsorption 26
1.10 Objectives and Scope of this Study 30
2.0

Experimental

 32
  2.1 Catalysts and Characterization 32
2.2 Gases and Apparatus 35
2.3 COad Measurements 36
2.4 Had Measurements 38
2.5 Reactivity, Fractional Coverage of Reaction Intermediate Measurements 42
2.6 Catalyst Aging Study 43
2.7 H/D Isotope Effect Study 44
2.8 Had Measurement Experiments 44
3.0 Catalyst aging study in Rany Nickel 46
  3.1 Background 46
3.2 Experimental 49
3.3 Results 50
3.4 Discussion and Conclusions 56
4.0

Transient Study (12CO/13CO Switch) on Raney Nickel, 60 WT % Ni/SiO2 and Ni Powder

 74
  4.1 Background 74
4.2 Experimental 74
4.3 Results 74
4.4 Discussion 95
 

4.4.1

 Low Value of oCHx 95

4.4.2

 Comparison of Transient Methods with Other Independent Measurements in Coad 96

4.4.3

 COad and CO Dissociation 96

4.4.4

 Mechanistic Information Inferred from K and o 104

4.4.5

 Reactivity and Coverage of Reaction Intermediates 115

4.4.6

 Active Sites for Methanation 118

4.4.7

 Particle Size Effect 120

4.4.8

 Support Effect 122

4.4.9

 Effect of Nature of Ni Catalysts on k and o 123
4.5 Conclusion 126
5.0 H/D Isotope Effect on Raney Nickel, 60 wt % Ni/SiO2 and Nickel Powder 128
  5.1 Background 128
5.2 Results 128
5.3 Discussion 139
 

5.3.1

 Effect of CO Diffusion 146

5.3.2

 Effect of Surface Oxygen and Carbon Containing Species on H/D Isotope Effect 149
5.4 Conclusions 150
6.0 H2 Adsorption Study 151
  6.1 Background 151
6.2 Results 151
 

6.2.1

 The Amount of Adsorbed Hydrogen in the Absence of CO 153

6.2.2

 The Amount of Adsorbed Hydrogen in the Presence of CO 162
6.3 Discussion 183
 

6.3.1

 Stoichiometry of H/CO 183

6.3.2

 Equilibrium Between Had and H2 187

6.3.3

 Effect of Nature on Nickel Catalysts 188

6.3.4

 Sites for Adsorbed Hydrogen 192

6.3.5

 Adsorbed Hydrogen in 60 wt % Ni/SiO2 193

6.3.6

 Adsorbed Hydrogen in Raney Nickel 198
6.4 Conclusion 200
7.0

Summary

 202
 

Appendix A

 204
Appendix B 209
Bibliography 220