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標題: | 以鋯為基底之金屬有機骨架擔載鈀觸媒應用於甲醇分解產氫反應 Methanol Dehydrogenation over Palladium Nanoparticles Supported on Zirconium-Based Metal-Organic Frameworks |
作者: | Yu-Hsiang Wang 王鈺翔 |
指導教授: | 游文岳(Wen-Yueh Yu) |
關鍵字: | 金屬有機骨架,孔洞材料,鈀,奈米顆粒,溶劑熱沉積法,催化,甲醇分解產氫,原位紅外光譜鑑定, metal-organic framework,porous material,palladium,nanoparticle,solvothermal deposition in MOF,catalysis,methanol dehydrogenation,in-situ IR, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 金屬有機骨架(metal-organic frameworks, MOFs)具有高比表面積以及可調控的孔洞特性,因此相當適合應用在觸媒反應領域中。在本研究中,我們合成三種以鋯為基底的金屬有機骨架UiO-66、NU-902、PCN-222作為孔洞性擔體,以溶劑熱沉積法摻入鈀奈米顆粒。物化性質鑑定證實這些金屬有機骨架的結構、形貌和孔洞性質在擔載鈀之後沒有明顯改變,且不同尺寸的孔洞可以有效限制形成不同大小之鈀奈米顆粒。鈀在觸媒中有Pd(II)和Pd(0)兩種價態分布。 甲醇分解產氫反應被應用來觀察鈀擔載前後之觸媒的催化效果。活性測試結果顯示在反應溫度150-225oC的區間,僅擔載有鈀的觸媒Pd@Zr-MOFs具有催化活性,其中Pd@UiO-66具有最好的活性以及最低的活化能。Pd@UiO-66的高催化活性的可能緣自於最小的孔洞所形成的最小鈀奈米顆粒。從in-situ IR實驗中可以證實甲醇能在UiO-66的表面被活化形成甲氧基,而孔洞中的鈀奈米顆粒可以進一步轉化甲氧基為一氧化碳、甲醛、甲酸甲酯等後續產物,並同時產生氫氣,因此有利於整體甲醇產氫反應。 Metal–organic frameworks (MOFs) possess unique characteristics such as ultrahigh specific surface area and tunable pore structure, rendering them as ideal candidates for catalytic applications. In this study, three topologically distinct zirconium-based metal–organic frameworks (Zr-MOFs), i.e., UiO-66, NU-902, and PCN-222, were synthesized and employed as porous supports to incorporate Pd nanoparticles (NPs) via the solvothermal deposition in MOF (SIM) technique. Physicochemical characterizations confirm that the structural, morphological, and textural features of pristine Zr-MOFs are mainly preserved after the incorporation of Pd NPs. It is shown that the sizes of Pd NPs are controllable by the pore confinement of Zr-MOFs. There are two oxidation states, i.e., Pd(II) and Pd(0), in Pd@Zr-MOFs catalysts. Methanol dehydrogenation is employed to investigate the catalytic activities of Pd-free and Pd-containing MOFs (Pd@MOFs). Reaction testing shows that only Pd@MOFs display obvious catalytic activities at the temperature studied (150 – 225oC), and Pd@UiO-66 displays significantly higher catalytic activity and lower activation energy as compared to Pd@NU-902 and Pd@PCN-222 for methanol dehydrogenation. The observed enhanced performance of Pd@UiO-66 is attributed to the smaller size of Pd NPs due to smaller pore size of UiO-66. In-situ infrared spectroscopy characterizations suggest that the methanol is activated on the surface of UiO-66 to form methoxy adspecies, and the Pd NPs within the framework of UiO-66 aid in the further dehydrogenation of methoxy adspecies, thereby facilitating the overall dehydrogenation of methanol. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/50243 |
DOI: | 10.6342/NTU202002950 |
全文授權: | 有償授權 |
顯示於系所單位: | 化學工程學系 |
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