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姓名 洪碇傑(Hung, Ting-Chieh) 查詢紙本館藏 畢業系所 物理學系 論文名稱
(Methanol Decomposition on Rh Nanoclusters supported by Al2O3/NiAl(100)：A combined IRAS, TPD and PES study)相關論文 檔案 [Endnote RIS 格式]
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摘要(中) 我們以反射吸收式傅立葉轉換紅外線光譜儀(FT-RAIRS)、熱脫附質譜術(TPD)與以同步輻射作為光源的光電子能譜(PES)研究一氧化碳(CO)與甲醇(CH3OH)在銠(Rh)奈米粒子上的吸附、脫附與分解反應之觸媒模型。銠以蒸鍍的方式，在θ相氧化鋁成長為奈米粒子。
從IR吸收光譜上以CO作為探測物的結果發現CO傾向於吸附在Rh奈米粒子的on-top site上，沒有其他像是bridge或是hollow的吸附site被探測到。由CO的TPD脫附譜線則顯示CO的脫附有兩個峰值：一個位於430 K（在Rh單晶上也有出現），一個則位於360 K（我們認為是來自於較小的Rh奈米粒子上脫附的CO）。由PES光譜則指出CO於Rh奈米粒子上分解成為原子碳(C)的比率約介於21到55%（與Rh奈米粒子的覆蓋率及大小有關）。在Rh奈米粒子在加熱至700 K之後，IR吸收光譜上顯示其吸收譜線並未改變，但在TPD譜線上則顯示低溫脫附的CO比率提升，我們認為這是因為Rh奈米粒子的尺寸所造成的。
甲醇吸附於Rh奈米粒子上將會進行脫氫反應，而脫氫反應開始於200 K之前且部分CO將會分解成為原子碳。甲醇分解產生的CO會在300 K開始脫附，而來自於CD3OD的D2則會於200 K開始脫附，我們沒有發現任何的中間產物。而在PES成果中顯示有43.1 ± 2.0 %的甲醇會分解成原子碳，由此結果顯示甲醇分解成CO的機率約為86.9 ± 4.5 %。
而將樣品加熱至700 K後並不會造成Rh奈米粒子的氧化。在TPD的脫附譜線中顯示，由甲醇分解產生的CO與直接吸附的分子CO的脫附量的比率較未經過加熱處理的樣品有所提升。1 ML的Rh其比率由47.2 ± 1 % 提升至54.4 ± 10 %，而4 ML的Rh其比率由39.9 ± 10 % 提升至77.9 ± 10 %。而甲醇分解反應的CO產率也有所提升，在4 ML的Rh上甲醇分解反應由原本的64.9 %提升至83.9 %，與我們的CO比率的成果一致。
摘要(英) Methanol decomposition on Rh nanoclusters supported by Al2O3/NiAl(100) as a model system is studied by IRAS, TPD and PES. The study contained two parts: surface structures of Rh clusters probe with CO and methanol decomposition on Rh nanoclusters. The Rh nanoclusters are grown from vapor deposition.
The IRAS spectra with CO as a probe show that the CO adsorbed on on-top site of Rh nanoclusters; no other site such as bridge or hollow site have been detected. The CO TPD spectra show that CO desorbed with two distinct peaks, one at 430 K, which is observed for CO on Rh single crystal results and the other at about 360 K, which is observed for CO on small Rh clusters. The PES spectra show that the CO dissociation rate ranges between 21 and 55 %, depending on the coverage and hence the size of the clusters. For the clusters annealed to 700 K, the IRAS spectra show the same CO absorption band but the CO TPD spectra show the proportion of low temperature desorption increases. We argue that the desorption temperature depends on the cluster size.
Adsorbed methanol was dehydrogenated on the nanoclusters. The dehydrogenation to CO began below 200 K, and some of the CO formed from the dehydrogenated methanol dissociated into atomic carbon. Our PES results confirm that about 21 - 55 % of molecularly adsorbed CO dissociates into atomic carbon, depending on the size of the clusters. The produced CO desorbed above 300 K and D2 from methanol-d4 above 200 K; no intermediate species were detected in the dehydrogenation process. The PES results show the ratio of methanol dissociating into atomic C is about 43.1 ± 2.0 %. This result suggests that the probability of methanol decomposed into CO is about 86.9 ± 4.5 %.
Annealing the sample to 700 K does not result in oxidation of the Rh clusters. The ratio of CO TPD desorption intensities from dehydrogenated methanol and molecularly adsorbed CO on the annealed Rh clusters is greater than that on the pristine Rh clusters. For 1 ML Rh, the ratio increases from 47.2 ± 1 % to 54.4 ± 10 %, and for 4 ML Rh, the ratio increases from 39.9 ± 10 % to 77.9 ± 10 %. The fraction of monolayer methanol undergoing dehydrogenation on the annealed Rh clusters is also greater than that on the pristine Rh clusters. On the annealed 4 ML Rh, the fraction of methanol undergoing dehydrogenation increased to 83.9 % (from 64.9 %), consistent with the result of CO ratio.
關鍵字(中) ★ 甲醇
★ 銠
★ 觸媒模型
★ 反應關鍵字(英) ★ Methanol
★ Rh
★ UHV
★ IR
★ PES
★ TPD論文目次 Contents
摘要 i
Abstract ii
誌謝 iv
List of Figure ix
List of Table xvi
Chapter 1 Introduction 1
Chapter 2 Literature Survey 4
2.1 The characterization of Rh nanoclusters on Alumina surface 4
2.2 CO on Rh single crystal surfaces and supported clusters 9
2.2.1 CO adsorption and desorption on single crystal ………………………………………………...10
2.2.2 CO adsorption and desorption on Rh/Al2O3 /NiAl(110) …………………………………………….13
2.3 Methanol decomposition on Rh single crystal 17
Chapter 2 Reference 22
Chapter 3 Experimental Methods & Apparatus 24
3.1 Experimental methods 24
3.1.1 Cleaning NiAl(100) 24
3.1.2 θ-Al2O3 ultrathin film growth 27
3.1.3 Vapor deposition of Rh 28
3.1.4 Methanol Adsorption and Reaction 28
3.2 Temperature Programmed Desorption 29
3.3 Infrared reflection adsorption spectroscopy 34
3.3.1 The principle of IRAS 34
3.3.2 Fourier Transform Interferometers 38
3.4 Photoemission Spectroscopy (PES) 40
3.4.1 PES analysis System 40
3.4.2 X-ray Photoelectron Spectroscopy (XPS) 41
3.5 LEED and AES 44
3.5.1 Low Energy Electron Diffraction (LEED) 44
3.5.2 Auger Electron Spectroscopy (AES) 45
Chapter 3 Reference 47
Chapter 4 Results and discussions 49
4.1 Adsorbed CO as a probe of Rh and annealed Rh clusters on thin film Al2O3/NiAl(100) 49
4.1.1 TPD spectra for CO on Rh/Al2O3/NiAl(100) 49
4.1.2 CO IRAS and PES spectra from Rh clusters on thin film Al2O3/NiAl(100) 51
4.1.3 CO on annealed (to 700 K) Rh clusters on Al2O3/NiAl(100) 58
4.2 Methanol decomposition on Rh clusters/Al2O3/NiAl(100) 61
4.2.1 TPD spectra for methanol on Rh clusters 61
4.2.2 IRAS spectra for methanol on Rh clusters 64
4.2.3 PES spectra for methanol on Rh clusters 67
4.3 Methanol decomposition on annealed to 700 K Rh clusters 72
4.3.1 TPD spectra for methanol on annealed Rh clusters 72
4.3.2 IRAS spectra for methanol on annealed Rh clusters 74
4.4 PES spectra for Rh clusters 76
Chapter 4 Reference 80
Chapter 5 Conclusion 82
參考文獻 Chapter 2 Reference
[1] 廖振和, A STM study of Rh and Rh-Au Bimetallic Nanoclusters on the θ-Al2O3/NiAl(100), 中央大學碩士論文，桃園縣，民國102年。
[2] Marcus Baumer and Hans-Joachim Freund, “Metal deposits on well-ordered oxide films”, Progress in Surface Science, Vol. 61, pp. 127 - 198, 1999.
[3] U. Heiz, A. Sanchez, S. Abbet, and W.-D. Schneider, “Catalytic Oxidation of Carbon Monoxide on Monodispersed Platinum lusters:? Each Atom Counts”, J. Am. Chem. Soc., Vol. 121, pp.3214, 1999.
[4] Elaine M. McCash, Surface Chemistry, Oxford University Press, 2001.
[5] A. Schlapka, U. Kasberger, D. Menzel, P. Jakob, “Vibrational spectroscopy of CO used as a local probe to study the surface morphology of Pt on Ru(001) in the sub-monolayer regime”, Surface Science, Vol. 502, pp.129 – 135.
[6] Maarten M.M. Jansen, Freek J.E. Scheijen, Jonathan Ashley, Ben E. Nieuwenhuys, J.W. Niemantsverdriet (Hans). “Adsorption/desorption studies of CO on a rhodium(100) surface under UHV conditions: Acomparative study using XPS, RAIRS, and SSIMS”, Catalysis Today, Vol. 154, pp. 53 – 60, 2010.
[7] I. Nakamura, Y. Kobayashi, H. Hamada, T. Fujitani, “Adsorption behavior and reaction properties of NO and CO on Rh(111)”, Surface Science, Vol. 600, 3235 – 3242, 2006.
[8] M. Frank, R. Kuhnemuth, M. Baumer and H.-J. Freund, “Oxide-supported Rh particle structure probed with carbon monoxide”, Surface Science, Vol. 427, pp. 288 – 293, 1999.
[9] S. Andersson, M. Frank, A. Sandell, A. Giertz, B. Brena, P. A. Bruhwiler, and N. Martensson, J. Libuda, M. Baumer, and H.-J. Freund, “Temperature dependent XPS study of CO dissociation on small Rh particles”, Vacuum, Vol. 49, pp. 167 – 170, 1998.
[10] John E. Parmeter, Xudong Jiang and D. Wayne Goodman, “The adsorption and decomposition of methanol on the Rh(100) surface”, Surface Science, Vol. 240, pp. 85 - 100, 1990.
[11] Carl Houtman and Mark A. Barteau, “Reactions of Methanol on Rh(111) and Rh(111)-(2×2)O Surfaces: Spectroscopic Identification of Adsorbed Methoxide and η-Formaldehyde”, Langmuir, Vol. 6, pp. 1558 – 1566, 1990.
Chapter 3 Reference
[1] Elaine M. McCash, Surface Chemistry, Oxford University Press, 2001.
[2] Hans Luth, Surface and Interfaces of Solid (2nd), Springer-Verlag, 1993.
[3] John B. Hudson, Surface Science: an introduction, J. Wiley & Sons, 1998.
[4] Harald Ibach, Physics of Surfaces and Interfaces, Springer-Verlag, 2006.
[5] Skoog D.A. et al., Principles of Instrumental Analysis (4th), Saunders College, 1992.
[6] P. Hollins and J. Pritchard, “Infrared studies of chemisorbed layers on single crystals”, Progress in Surface Science, Vol. 19, pp. 275 – 349, 1985.
[7] F. M. Hoffmann, “Infrared reflection-absorption spectroscopy of adsorbed molecules”, Surface Science Reports, Vol. 3, pp. 109 – 192, 1983.
[8] A.M. Bradshaw, E. Schweizer, Infrared reflection absorption spectroscopy of adsorbed molecules, in: R.E. Hester(Ed.), Advances in Spectroscopy: Spectroscopy of Surfaces, Wiley, New York, 1988.
[9] R. G. Greenler, “Infrared Study of Adsorbed Molecules on Metal Surfaces by Reflection Techniques”, J. Chem. Phys., Vol. 44, pp. 310, 1966.
[10] Marcus Baumer and Hans-Joachim Freund, “Metal deposits on well-ordered oxide films”, Progress in Surface Science, Vol. 61, pp. 127 - 198, 1999.
[11] ABB FT-IR reference manual
[12] 李冠卿，近代光學，聯經出版社，1988
[13] J. C. Vickerman, Surface Analysis – The Principal Techniques, Jon Wiley & Sons, 1997.
[14] A. K. Stantra and D.W. Goodman, J.Phys: Condens Matter, Vol.14, R31 - R62. 2002.
[15] D.j. O’Connor, B. A. Sexton, R. St. C. Smart, Surface Analysis Methods in Materials Science, Springer-Verlag, 1992.
[16] Y. W. Yang, L. J. Fan, “High-Resolution XPS Study of Decanethiol on Au(111):? Single Sulfur?Gold Bonding Interaction”, Langmuir, Vol. 18, pp. 1157 – 1164, 2002.
Chapter 4 Reference
[1] J Maarten M.M. Jansen, Freek J.E. Scheijen, Jonathan Ashley, Ben E. Nieuwenhuys, J.W. Niemantsverdriet (Hans). “Adsorption/desorption studies of CO on a rhodium(100) surface under UHV conditions: Acomparative study using XPS, RAIRS, and SSIMS”, Catalysis Today, Vol. 154, pp. 53 – 60, 2010.
[2] I. Nakamura, Y. Kobayashi, H. Hamada, T. Fujitani, “Adsorption behavior and reaction properties of NO and CO on Rh(111)”, Surface Science, Vol. 600, 3235 – 3242, 2006.
[3] Jan-Henrik Fischer-Wolfarth, Jason A. Farmer, J. Manuel Flores-Camacho, Alexander Genest, Ilya V. Yudanov, Notker Rosch, Charles T. Campbell, Swetlana Schauermann, and Hans-Joachim Freund, “Particle-size dependent heats of adsorption of CO on supported Pd nanoparticles as measured with a single-crystal microcalorimeter”, Physical Review B, Vol. 81, 241416, 2010
[4] S. Andersson, M. Frank, A. Sandell, A. Giertz, B. Brena, P. A. Bruhwiler, and N. Martensson, J. Libuda, M. Baumer, and H.-J. Freund, “Temperature dependent XPS study of CO dissociation on small Rh particles”, Vacuum, Vol. 49, pp. 167 – 170, 1998.
[5] Gerard P. Michon, Final Answer, 2004-05-13.
[6] 廖振和, A STM study of Rh and Rh-Au Bimetallic Nanoclusters on the θ-Al2O3/NiAl(100), 中央大學碩士論文，桃園縣，民國102年。
[7] John E. Parmeter, Xudong Jiang and D. Wayne Goodman, “The adsorption and decomposition of methanol on the Rh(100) surface”, Surface Science, Vol. 240, pp. 85 - 100, 1990.
[8] Carl Houtman and Mark A. Barteau, “Reactions of Methanol on Rh(111) and Rh(111)-(2×2)O Surfaces: Spectroscopic Identification of Adsorbed Methoxide and η-Formaldehyde”, Langmuir, Vol. 6, pp. 1558 – 1566, 1990.
[9] S.H. Payne, H.J. Kreuzer, W. Frie, L. Hammer, K. Heinz, “Adsorption and desorption of hydrogen on Rh(311) and comparison with other Rh surfaces”, Surface Science, Vol. 421, pp. 279 – 295, 1999.
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