鑭系波洛斯凱特觸媒於甲醇部分氧化之研究

Lanthanum-transition Metal Perovskites for Methanol Partial Oxidation

黎家良(Chia-Liang Li)

指導教授 ： 林裕川

元智大學/工程學院/化學工程與材料科學學系/碩士(2011年)

摘要

本論文著眼於鑭系金屬波洛斯凱特觸媒LaBO3(B=錳、鈷和鐵) 與LaMn0.95B’0.05O3 (B’=鈀、鉑和銠) 於甲醇部分氧化(partial oxidation of methanol, POM)之應用。本研究使用不同的物理與化學方法鑑定觸媒的表面和本體。包括比表面積測定(BET)、結晶構造判定(XRD)、表面組成分析(EDS)、表面貴金屬價態分析(XPS)、程溫還原分析(H2-TPR)、程溫氧化分析(TPO)、程溫氧脫附分析(O2-TPD) 和甲醇程溫脫附分析 (CH3OH-TPD)。研究發現，以Mn做為B-site的波洛斯凱特觸媒擁有最好的活性，其主要反應路徑為甲醇燃燒。添加貴金屬的波洛斯凱特觸媒在還原能力和氧的活性相較於LaMnO3有明顯的改變，造成其在甲醇部分氧化反應上的差異，其中又以LaMnPd有最明顯的效果。波洛斯凱特觸媒的氧化還原特性可以促進甲醇部分氧化產生甲醛。因此，本研究也提出LaMnO3系波洛斯凱特觸媒進行甲醇部分氧化的反應機制。

關鍵字

波洛斯凱特 ； 貴金屬 ； 甲醇 ； 氧化 ； 氧化還原機制

並列摘要

This study investigates methanol partial oxidation over lanthanum transition metal based perovskites, i.e., LaBO3(B = Mn, Fe, and Co) and LaMn0.95 B’0.05O3(B’=Pd, Pt, and Rh). Their bulk and surface properties were characterized by appropriate physiochemical techniques including BET surface area measurement, XRD, EDS, XPS, H2-TPR, TPO, O2-TPD, and CH3OH-TPD. LaMnO3 shows better activity than LaFeO3 and LaCoO3. The major reaction route under oxidative environments is methanol combustion. The characterizations showed significant differences of reducibility and oxygen activity between promoted and un-promoted LaMnO3. Such deviants resulted in diverse catalytic behaviors in methanol partial oxidation. Among them, LaMnPd show the best performance. Perovskite’s redox property was discovered to enhance partial oxidation route to formaldehyde while oxygen activity played a central role in combustion. Accordingly, plausible reaction mechanism of methanol partial oxidation over LaMnO3 based perovskites was thereby proposed.

並列關鍵字

redox ； Perovskite ； noble metals ； methanol ； oxidation

參考文獻

2. C.D. Chang, Hydrocarbons from methanol. Catalysis Reviews-Science and Engineering, 25, 1-118 (1983).

6. J.M. Tatibouet, Methanol oxidation as a catalytic surface probe. Applied Catalysis A-General, 148, 213-252 (1997).

7. G.A. Olah, After oil and gas: methanol economy. Catalysis Letters, 93, 1-2 (2004).

8. G.A. Olah, Beyond oil and gas: The methanol economy. Angewandte Chemie-International Edition, 44, 2636-2639 (2005).

9. Y.C. Lin, K.L. Hohn, and S.M. Stagg-Williams, Hydrogen generation from methanol oxidation on. supported Cu and Pt catalysts: Effects of active phases and supports. Applied Catalysis a-General, 327, 164-172 (2007).