闡明鹼性系統下非晶型和β-MnO₂熱催化氧 化5-羥甲基糠醛為2,5-呋喃二甲酸的機制;Elucidating the Mechanism of Thermocatalytic Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid by Amorphous and Beta-MnO₂ Under Alkaline Systems

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Title:	闡明鹼性系統下非晶型和β-MnO₂熱催化氧化5-羥甲基糠醛為2,5-呋喃二甲酸的機制;Elucidating the Mechanism of Thermocatalytic Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid by Amorphous and Beta-MnO₂ Under Alkaline Systems
Authors:	趙牧生;Zhao, Mu-Sheng
Contributors:	化學工程與材料工程學系
Keywords:	5-羥甲基糠醛;2,5-呋喃二甲酸
Date:	2025-07-14
Issue Date:	2025-10-17 11:14:40 (UTC+8)
Publisher:	國立中央大學
Abstract:	5-羥甲基糠醛(5-Hydroxymethylfurfural, 5-HMF)是一種極具潛力的生質化學品，其氧化產物 2,5-呋喃二甲酸(2,5-furandicarboxylic acid , FDCA)可作為聚乙烯2,5-呋喃二甲酸 (polyethylene 2,5-furandicarboxylate, PEF)的合成單體，並且可以取代傳統石化來源的聚對苯二甲酸乙二醇酯(poly(ethylene terephthalate, PET)。目前，5-HMF 的氧化主要透過電催化或熱催化方式進行，兩者皆可達成高轉化率與高選擇性產率。然而，部分熱催化系統仰賴貴金屬如鉑、金或鈀作為催化劑，不僅成本高昂，且資源有限，限制了其工業應用的可行性。此外，已有部分研究指出，在鹼性環境下進行氧化反應有助於提升FDCA 的產率，但傳統氫氧化鈉鹼性系統存在腐蝕性高、無法回收及產生大量鹽類廢水等環境負擔。本研究以氯化膽鹼與尿素(摩爾比 1:2)組成的深共溶溶劑(deep eutectic solvent , DES) 作為鹼性環境，其具備低毒性、可再生、生物可分解等綠色溶劑特性，並選用非貴金屬的二氧化錳(Manganese dioxide, MnO2)作為催化劑，搭配氧氣作為氧化劑，建立一套滿足綠色化學理念的催化反應系統。考量5-HMF 氧化為FDCA 具有複雜的並聯與串聯反應路徑，中間產物包含5-羥甲基-2-呋喃甲酸(5-Hydroxymethyl-2-furancarboxylic acid, HMFCA)、2-呋喃甲醛(5-Formyl-2-furancarboxylic Acid, FFCA)等多種物質，使得反應選擇性與機制探討具挑戰性。因此，本研究不僅系統性比較了兩種較常被用來進行催化的晶型-MnO₂、Amorphous-MnO₂對催化效能的影響，亦探討了DES 組成比例對反應的影響，並透過高效液相層析儀(High-Performance Liquid Chromatography, HPLC)量測 5- HMF 的轉化率及 FDCA 的產率，以及利用氣相層析-質譜儀(Gas Chromatography–Mass Spectrometry, GC-MS)鑑定反應中的中間產物與副產物，用以了解反應機制。;5-Hydroxymethylfurfural (5-HMF) is a highly promising biomass-derived chemical, and its oxidation product, 2,5-furandicarboxylic acid (FDCA), can serve as a monomer for the synthesis of polyethylene 2,5-furandicarboxylate (PEF), offering a potential replacement for conventional petroleum-based polyethylene terephthalate (PET). Currently, the oxidation of 5- HMF is mainly achieved through electrocatalysis or thermocatalysis, both of which can deliver high conversion rates and excellent selectivity. However, certain thermocatalytic systems rely on noble metals such as platinum, gold, or palladium as catalysts, which are costly and scarce, thereby limiting their feasibility for industrial applications. In addition, some studies have shown that alkaline conditions can enhance FDCA yields, but conventional sodium hydroxidebased systems suffer from high corrosivity, lack of recyclability, and the generation of large volumes of saline wastewater, raising environmental concerns. In this study, a deep eutectic solvent (DES) composed of choline chloride and urea at a molar ratio of 1:2 was employed as the alkaline medium. DES offers several advantages, including low toxicity, renewability, and biodegradability, making it a green solvent alternative. Manganese dioxide (MnO₂), a non-noble metal catalyst, was selected as the catalyst, with oxygen as the oxidant, to establish a catalytic system that aligns with the principles of green chemistry. Given that the oxidation of 5-HMF to FDCA involves complex parallel and sequential reaction pathways, accompanied by multiple intermediates such as 5- hydroxymethyl-2-furancarboxylic acid (HMFCA) and 2-formylfuran carboxylic acid (FFCA), controlling the reaction selectivity and elucidating the mechanism pose considerable challenges. Therefore, this study systematically compares the catalytic performance of two commonly used MnO₂ crystal forms β-MnO₂ and amorphous-MnO₂and investigates the influence of DES composition on reaction outcomes. The conversion of 5-HMF and yield of FDCA were quantified using high performance liquid chromatography (HPLC), while gas chromatographymass spectrometry (GC-MS)was employed to identify intermediates and byproducts, providing insights into the underlying reaction mechanism.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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