In-situ investigations of adsorbed hydrocarbons [Elektronische Ressource] : model systems of heterogeneous catalysis / vorgelegt von Christian Papp

Prepress

Informations

• Publié par: friedrich-alexander-universitat_erlangen-nurnberg
• Publié le: 01 janvier 2007
• Nombre de lectures: 17
• Poids de l'ouvrage: 3 Mo

Extrait

In-situ investigations of adsorbed hydrocarbons
– model systems of heterogeneous catalysis






Den Naturwissenschaftlichen Fakultäten
der Friedrich-Alexander-Universität Erlangen-Nürnberg
zur
Erlangung des Doktorgrades












vorgelegt von
Christian Papp
aus Erlangen

Als Dissertation genehmigt von den Naturwissenschaftlichen Fakultäten der
Universität Erlangen-Nürnberg

























Tag der mündlichen Prüfung: 12.07.2007

Vorsitzender der Promotionskommission: Prof. Dr. Bänsch

Erstberichterstatter: Prof. Dr. Steinrück

Zweitberichterstatter: Prof. Dr. Libuda
IITable of contents
1 Introduction............................................................................................1
2 Fundamentals and techniques ..............................................................5
2.1 X-ray photoelectron spectroscopy (XPS) ................................................. 5
2.1.1 General remarks......................................................................................... 5
2.1.2 Chemical shift............................................................................................. 9
2.1.3 Vibrational excitations in XPS................................................................... 10
2.1.4 Line profiles .............................................................................................. 15
2.1.5 Quantification of XPS data and photoelectron diffraction ......................... 16
2.1.6 X-rays from a synchrotron radiation source.............................................. 17
2.2 TPXPS and TPD .................................................................................... 19
2.2.1 Basic principles......................................................................................... 19
2.2.2 Primary kinetic isotope effect in TPXPS and in TPD experiments............ 21
2.3 Low energy electron diffraction .............................................................. 22
2.4 Molecular beams 23
2.5 Basic considerations for the vibrational properties of molecules ........... 24
3 Experimental section...........................................................................29
3.1 “The Synchrotron machine”.................................................................... 29
3.2 Surface endstation of beamline I 5-11 at MAX Lab................................ 31
4 Adsorption and reaction of benzene....................................................33
4.1 Adsorption of pure benzene layers ........................................................ 34
4.1.1 Introduction............................................................................................... 34
4.1.2 Adsorption of benzene (C H and C D ) at 200 K .................................... 36 6 6 6 6
4.1.3 Adsorption at 125 K and thermal evolution up to 220 K............................ 48
4.2 Coadsorption experiments with benzene ............................................... 54
4.2.1 Benzene coadsorbed with CO: (2 √3x2 √3) R30° benzene + 2 CO............ 55
4.2.2 Benzene coadsorbed with NO: (3 x 3) benzene +2 NO............................ 59
4.3 Binding energy shifts in the XP spectra ................................................. 64
4.4 Summary ................................................................................................ 65
5 Adsorption and reaction of cyclohexene .............................................69
5.1 Introduction............................................................................................. 70
5.2 Adsorption .............................................................................................. 73
III
5.2.1 Adsorption experiments at 125 K.............................................................. 73
5.2.2 Adsorption at elevated temperatures........................................................ 77
5.3 Thermal evolution................................................................................... 82
5.3.1 TPXPS experiment of the layer adsorbed at 210 K .................................. 82
5.3.2 Temperature programmed desorption data .............................................. 84
5.3.3 TPXPS experiment of cyclohexene adsorbed at 125 K............................ 85
5.4 Summary and conclusions ..................................................................... 88
6 Adsorption and reaction of heterocycles .............................................91
6.1 Introduction............................................................................................. 92
6.2 Adsorption of furan and pyrrole.............................................................. 95
6.3 Reaction of furan and pyrrole............................................................... 101
6.4 Summary .............................................................................................. 112
7 Methane adsorption on stepped platinum surfaces...........................115
7.1 Introduction........................................................................................... 116
7.2 Results and discussion......................................................................... 118
7.2.1 Adsorption experiments on Pt(355) and Pt(322) .....................................118
7.2.2 Thermal evolution of the adsorbed species .............................................127
7.2.3 Radiation induced chemistry ...................................................................131
7.2.4 Summary and conclusions ......................................................................134
7.3 Methane adsorption on silver modified stepped Pt surfaces................ 135
7.3.1 Preparation of the silver layers ................................................................135
7.3.2 Adsorption of methane on the two silver modified stepped platinum
surfaces............................................................................................................136
7.3.3 Thermal evolution of methyl layers on silver precovered platinum surfaces
.........................................................................................................................140
7.3.4 Conclusions and summary ......................................................................142
7.4 Kinetic isotope effects in the adsorption and decomposition of methane
on stepped platinum surfaces .................................................................... 143
7.4.1 Kinetic isotope effects in the adsorption of methane ...............................144
7.4.2 Kinetic isotope effect in the thermal evolution of methane.......................149
7.4.3 Summary .................................................................................................158
7.5 Summary .............................................................................................. 158
8 Summary...........................................................................................163
IV8.1 Zusammenfassung...............................................................................167
9 Appendixes........................................................................................169
9.1 Appendix to chapter 2 ..........................................................................169
9.1.1 Changes in the bond length and the vibrational excitations upon core
excitation ..........................................................................................................169
9.2 Appendix to chapter 4171
9.2.1 Modeling of XP spectra of benzene with different functions ....................171
9.2.2 Changes in desorption temperatures upon heat rate variation ................173
9.2.3 Calculation of the minority population for the adsorption of benzene at 200
K.......................................................................................................................174
9.2.4 Low temperature adsorption of deuterated benzene ...............................175
9.3 Appendix to chapter 6 ..........................................................................176
9.3.1 Fits of furan C 1s spectra obtained during a TPXPS experiment ............176
9.3.2 Fits of pyrrole C 1s spectra obtained during a TPXPS ex..........177
9.4 Appendix to chapter 7179
9.4.1 Supporting information to chapter 7.2......................................................179
9.4.2 Transition and characteristic temperatures together with the respective
activation energies of methyl on Pt(111) ..........................................................181
9.4.3 Kinetic energies of the methane ..............................................................184
Literature ..............................................................................................185


V1 Introduction 1

1 Introduction
In the past decades surface science has become a strongly evolving and still growing
field of science. It is not only a large part of condensed matter physics but also an
interdisciplinary field with great relevance for other research areas. T