簡易檢索 / 詳目顯示

研究生: 鍾國偉
論文名稱: 乙醇在Rh/Ce0.5Zr0.5O2(111)氧化金屬表面脫氫的可能反應機構
Computational Studies of Reaction Mechanisms of Dehydrogenation of Ethanol on the Rh/Ce0.5Zr0.5O2 (111) Surface
指導教授: 何嘉仁
學位類別: 碩士
Master
系所名稱: 化學系
Department of Chemistry
論文出版年: 2007
畢業學年度: 95
語文別: 中文
論文頁數: 71
中文關鍵詞: 乙醇脫氫化學含氧量
論文種類: 學術論文
相關次數: 點閱:173下載:2
分享至:
查詢本校圖書館目錄 查詢臺灣博碩士論文知識加值系統 勘誤回報
  • 中文摘要
    隨著化石燃料的日漸枯竭,人們正在找尋可以替代石油的能源來源。而氫氣(H2)是目前較佳的的料燃之一,將氫氣使用於內燃機引擎中,其燃燒產生的物質對環境是沒有污染性的。此外,氫氣也可以應用於H2/O2燃料電池的高效率發電方面,且具有相當的實用價值。乙醇是氫氣主要的來源之一,乙醇在合適的氧化物表面上時,加以合適的溫度,可以有絕佳的催化效果,而產生高效率的脫氫反應。在本文中,我們利用週期性的電子密度泛函理論的計算方法,探討乙醇在Rh/Ce0.5Zr0.5O2(111)表面上之可能的分解反應機構。結果發現,乙醇若以該分子的氧端吸附在Rh/CeO2(111)表極面的Ce上,比起其他表面原子而言(例如Rh與O原子),將有著較高的吸附能。是故乙醇首先將會以該氧端吸附在Rh/CeO2(111)表面的Ce上,而形成
    CH3CH2O(H)–Ce(a),再藉由接續的脫氫反應(斷去O–H以及H2C–H)
    ,之後形成一個穩定環狀的中間物Rh–CH2CH2–Ce(a) (oxametallacycle)。再者,該中間物會先在α-碳上接連斷去兩個C–H鍵而形成吸附中間物Rh–CH2CO–Ce(a)。最後Rh–CH2CO–Ce(a)將藉由斷去C–C鍵結而形成Rh–CH2(a) + 4H(a) + CO(g)的產物,最後這些產物在高溫下再產生脫附反應,而形成CH4(g) + H2(g) + CO(g)。

    Abstract
    Hydrogen is considered a desirable fuel for several reasons, among which hydrogen is the least polluting fuel that one can use in an internal–combustion engine, and it can serve in a highly efficient hydrogen/oxygen fuel cell to produce electricity. As a result, we applied periodic density–functional theory (DFT) to investigate the dehydrogenation of ethanol on a Rh/Ce0.5Zr0.5O2(111) surface. Ethanol is calculated to have the greatest energy of adsorption when the oxygen atom of the molecule is adsorbed onto a Ce atom in the surface, relative to other surface atoms (Rh or O). Before forming an oxametallacyclic compound (Rh–CH2CH2O–Ce(a)), two hydrogen atoms from ethanol are first eliminated; the barriers for dissociation of the O-H and the β-carbon (CH2–H) hydrogens are calculated to be 15.2 and 26.9 kcal/mol, respectively. The dehydrogenation continues with loss of two hydrogens from the α-carbon, forming an intermediate species Rh–CH2CO–Ce(a), . Scission of the C–C bond occurs at this stage to form Rh–CH2(a) + 4H(a) + CO(g). At high temperatures, these adsorbates desorb to yield the final products CH4(g), H2(g) and CO(g).

    目 錄 中文摘要 iii 英文摘要 iv 第一章、前言 1 第二章、 計算方法 7 第三章、乙醇在1Rh/Ce0.5Zr0.5O2 (111)slab上的脫氫反應機構 §3-1 固溶體的模擬 8 §3-2 slab切面的選擇與模擬 9 §3-3 乙醇吸附在表面Ce原子與Zr原子反應的比較 12 §3-4 1Rh 吸附在Ce0.5Zr0.5O2 (111)表面的結構 18 §3-5 乙醇在1Rh/Ce0.5Zr0.5O2 (111)slab脫H原子的可能反應機 構 20 第四章、乙醇在4Rh/Ce0.5Zr0.5O2 (111)slab上的脫氫反應機構 §4-1. 4Rh 吸附在Ce0.5Zr0.5O2 (111)表面的結構…………………38 §4-2. 乙醇在4Rh/Ce0.5Zr0.5O2 (111)slab上的吸附……………….39 §4-3. 乙醇在4Rh/Ce0.5Zr0.5O2 (111)slab脫H原子的可能反應機 構……………………………………………………………………..42 §4-4. 4Rh/Ce0.5Zr0.5O2 (111)表面OSC的討論…………………….57 第五章、結論......................................................................................60 參考文獻..............................................................................................62 第六章、附錄(乙醇在CeO2(111) cluster model的計算)………….65 §6-1. 計算軟體與方法…………………………………………….65 §6-2. CeO2 cluster model的模擬…………………………………..66 §6-3. 乙醇在CeO2(111) cluster model的吸附能…………………67 §6-4. 乙醇在2Rh/CeO2(111) cluster model的吸附與O-H基的 解離………………………………………………………………….69

    參考文獻:
    (1) Chou, H. L ; Jiang, J. C. The Chinese Chem. Soc., 2006, 64, No. 3, 301
    (2) Taylor, K. C. Catal. Rev. Sci. Eng. 1995, 35, 457.
    (3) Basic Research Needs for Vehicles of the Future; Eisenberger, P. M., Ed; Princeton Materials Institute: Princeton, NJ, 1995.
    (4) Kaspar, J. ; Fornasiero, P.; Graziani, M. Catalysis Today .1999, 50, 285
    (5) Taylor, K. C.; Proc. Catalytic and Automotive Pollution Control, Brussels, Belgium, (1986)
    (6) Fisher, G. B.; Thesis, J. R.; Casarella, M. V.; Mahan, S. T.: SAE Tech. Pap. Ser., No. 931034 (1993)
    (7) Shriver, D.F.; Atkins, P.W. Inorganic Chemistry thired edition.322
    (8) Kenevey, K.; Valdivieso, F.; Soustelle, M.; Pijolat, M. Applied Catalysis B: Environmental 2001, 29, 93.
    (9) Kim, Y.J.; Thevuthasan , S.; Shutthananadan , V.; Perkins, C.L.; McCready, D.E.; Herman, G.S.; Gao, Y. ; Tran, T.T.; Chambers, S.A.; Peden, C.H.F. Journal of Electron Spectroscopy and Related Phenomena. 2002,126 ,177
    (10) Alan E.; Nelson. Kirk; Schulz, H. Applied Surface Science. 2003, 210, 206
    (11) Wang , J.A. ; Lopez , T.; Bokhimi , X.; Novaro, O. Journal of Molecular Catalysis A: Chemical. 2005, 239, 249
    (12) Diagne, C.; Idriss , H.; Kiennemann, A. Catalysis Communications. 2002, 3, 565
    (13) Handbook of Chemistry and Physics, 76th ed., CRC Press,
    Baton Rouge, FL, 1995.
    (14) Kaspar, J.; Fornasiero, P.; Graziani, M. Catal. Today 1999, 50, 285.
    (15) Madier, Y.; Descorme, C.; Le Govic, A. M.; Duprez, D. J. Phys. Chem. B 1999, 103, 10999
    (16) Diagne , C.; Idriss , H.; Pearson , K.; Angel , M.; Kiennemann , A. C. R. Chimie. 2004, 7, 617
    (17) Kresse, G.; Hafner, J. Phys. Rev. B .1993, 47, 558.
    (18) Kresse, G.; Furthmuller, J. Comp. Mater. Sci. 1996, 6, 15.
    (19) Kresse, G.; Hafner, J. Phys. Rev. B 1996, 54, 169.
    (20) White, J. A.; Bird, D. M. Phys. Rev. B 1994, 50, 4954.
    (21) Perdew, J. P.; Chevary, J. A.; Vosko, S. H.; Jackson, K.A.; Pederson,
    M. R.; Singh, D. J.; Fiolhais, C. Phys. Rev. B 1992, 46, 6671.
    (22) (a)Blochl, P. E. Phys. Rev. B 1994, 50, 17953. (b) Kresse, G.; Joubert, D. Phys. Rev. B 1999, 59, 1758
    (23) Alcala, R. ; Mavrikakis, M.; Dumesic, J. A. Journal of Catalysis. 2003, 218, 178
    (24) Wyckoff, R.W.G. in Crystal Structures, volume 1, Interscience, John Wiley & Sons, 1963.
    (25) Chen, H.L.; Liu, S.H. ; Ho, J.J. J. Phys. Chem. B 2006, 110, 14816
    (26) Idriss, H. Platinum Metals Rev., 2004, 48, (3), 105
    (27) Prakash, D.; Vaidya, A. E. R. Chemical Engineering Journal. 2006, 117 , 39
    (28) Duan, S.; Senkan, S. Ind. Eng. Chem. Res. 2005, 44, 6381
    (29) Yee, A.; Morrison, S.J.; Idriss, H. Catalysis Today. 2000, 63, 327
    (30) Sheng, P.Y.; Yee, A.; Bowmaker, G.A.; Idriss, H. Journal of Catalysis. 2002, 208, 393
    (31)Ye, Q.; Gao, Q.; Zhang, X.R.; Xu, B.Q. Catalysis Communications. 2006, 7, 589
    (32) Jones, G.S. ; Mavrikakis, M. ; Barteau, M.A.; Vohs, J.M. J. Am. Chem. Soc. 1998, 120, 3196
    (33) Atherton, M. J.; Fawcett, J.; Holloway, J. H.; Hope, E. G.; Karacar, A.; Russell, D. R.; Saunders, G. C. J. Chem. Soc. Dalton Trans. 1996, 15, 3215.
    (34) Atherton, M. J.; Fawcett, J.; Holloway, J. H.; Hope, E. G.; Martin, S. M.; Russell, D. R.; Saunders, G. C. J. Organomet. Chem. 1998, 555, 67.
    (35) Breen, J.P.; Burch, R.; Coleman, H.M. Applied Catalysis B: Environmental. 2002, 39, 65
    (36) Roh, H.S.; Platon, A.; Wang, Y.; King, D.L. Catalysis Letters. 2006, 110, Nos. 1–2
    (37) Liguras, D.K.; Kondarides, D.I. ;Verykios, X.E. Applied Catalysis B: Environmental. 2003, 43, 345
    (38) Ruettinger, W.; Liu, X.; Farrauto, R.J. Applied Catalysis B: Environmental. 2006, 65, 135
    (39) Liu, Z.P. ;Jenkins, S.J. ; King, D.A. Physical review letters. PRL 94, 2005, 196102

    下載圖示
    QR CODE