本文關鍵詞： 5-羥甲基糠醛 選擇氧化 2 5-呋喃二甲酸 2 5-二甲酰基呋喃　出處：《華東理工大學》2017年博士論文　論文類型：學位論文

【摘要】：生物質作為一種清潔的可再生資源,可作為化石能源的替代品,是未來可持續(xù)能源系統(tǒng)的重要組成部分。當前研究階段,生物質轉化過程主要通過生物發(fā)酵、化學轉化等方法得到一系列平臺化合物,如丁二酸、5-羥甲基糠醛(5-HMF)等,然后通過催化轉化合成各類高附加值化學品和燃料。其中,5-HMF氧化反應的產(chǎn)物2,5-呋喃二甲酸(FDCA)和2,5-二甲�；秽�(DFF)有重要的工業(yè)化應用價值,近幾年受到廣泛關注。本文針對當前5-HMF選擇氧化反應研究中需引入強堿、貴金屬催化劑成本高以及非貴金屬催化劑活性組分利用率低的問題,分別合成了堿式碳酸鋅(ZOC)負載的Au-Pd合金催化劑(Au-Pd/ZOC)、Mn-Co-O復合氧化物催化劑和改性二氧化鈦(P25)負載的M_nOx催化劑(M_nOx/P25-600-5h),考察相應催化劑在5-HMF選擇氧化反應中的活性,并對其物相組成、微觀結構等進行詳細表征,探究催化劑的微觀結構與催化性能間的關聯(lián)。本文的主要研究內容如下:為避免使用強堿性反應介質,通過水熱法合成ZOC載體,然后采用沉積-沉淀法制備了 Au-Pd/ZOC合金催化劑,在弱堿性條件下催化5-HMF選擇氧化反應可得到99%的FDCA收率。表征結果顯示Au和Pd形成納米合金粒子均勻地分散在載體ZOC上,Au和Pd之間存在的協(xié)同效應有助于提高催化活性。同時發(fā)現(xiàn)催化劑的活性順序與相應載體水溶液pH值的高低順序一致,說明載體的表面酸堿性質對催化活性有重要影響。此外,弱堿環(huán)境有利于穩(wěn)定ZOC載體,提高Au-Pd/ZOC的穩(wěn)定性,使其循環(huán)使用7次無明顯活性降低。針對貴金屬催化劑成本高的問題,采用液相混合固相煅燒法合成了 Mn-Co-O復合氧化物催化劑,其活性遠高于采用相同方法制備的單一 M_nO_2和Co_3O_4。當Mn/Co摩爾比為1、鍛燒溫度為400℃時,所制備的Mn_0.50-Co_0.50-O催化劑活性最高,反應2h后5-HMF轉化率為42.6%,DFF選擇性高達98.0%。結果表明,Mn_0.50-Co_0.50-O復合氧化物中鈷氧化物的引入可形成CoM_nO_3相態(tài),使催化劑表面Mn~(4+)/Mn~(3+)比例和暴露的晶格氧濃度顯著提高,具有更高的表面氧移動性,從而提高催化活性。另外,Mn_0.50-Co_0.50-O復合氧化物可以循環(huán)再生5次而催化活性無明顯降低,表明其具有優(yōu)異的穩(wěn)定性。為提高M_nO_x基催化劑活性組分的利用效率,通過煅燒對載體二氧化鈦(P25)進行表面改性,然后采用等體積浸漬法制備得到一系列M_nO_x/P25-a-b催化劑(a,b分別為煅燒處理的溫度和時間)。當P25在600℃下煅燒5 h后所得到的M_nO_x/P25-600-5h催化劑表現(xiàn)出最高的活性,2 h內獲得33.2%的5-HMF轉化率及97.0%的DFF選擇性,該活性約為M_nO_x/P25的2倍。實驗結果表明,600℃煅燒處理P25后可使其表面可獲得最優(yōu)的銳鈦礦/金紅石相態(tài)比例,有助于提高催化劑的氧移動性,進而獲得高催化活性;同時qF燒處理后表面酸性位數(shù)目會明顯降低,減少反應過程中副反應的發(fā)生,從而提高DFF的選擇性。
[Abstract]:Biomass, as a clean renewable resource and a substitute for fossil energy, is an important component of sustainable energy systems in the future. A series of platform compounds were obtained by chemical conversion, such as 5-hydroxymethylfurfural succinic acid, 5-HMFs, and so on. Then various kinds of high added value chemicals and fuels were synthesized by catalytic conversion. The products of oxidation reaction of 5-HMF, 2HMF, FDCA and DFF, have important industrial application value. In recent years, extensive attention has been paid to the problems of introducing strong alkali, high cost of noble metal catalysts and low utilization of active components of non-noble metal catalysts in the study of 5-HMF selective oxidation reaction. The Au-Pd alloy catalysts supported on basic zinc carbonate (ZOC) and MnOx / MnOx catalysts supported on Au-PD / ZOC / Mn-Co-O oxides and modified titania P25) were synthesized respectively. The activity of the corresponding catalysts in the selective oxidation reaction of 5-HMF was investigated, and the phase composition of the catalysts was also investigated. The main contents of this paper are as follows: in order to avoid the use of strong alkaline reaction medium, ZOC support was synthesized by hydrothermal method. Then the Au-Pd/ZOC alloy catalyst was prepared by deposit-precipitation method. The FDCA yield of 99% can be obtained by catalytic selective oxidation of 5-HMF under weak alkalinity. The characterization results show that the synergistic effect between au and PD formed by the homogeneous dispersion of au and PD on the ZOC supports is helpful to improve the catalytic effect. At the same time, it was found that the order of activity of the catalyst was consistent with the pH value of aqueous solution of the corresponding carrier. The results show that the surface acid-base property of the support has an important effect on the catalytic activity. In addition, the weak base environment is beneficial to stabilize the ZOC support, improve the stability of the Au-Pd/ZOC, and reduce the activity of the Au-Pd/ZOC for 7 times. In view of the high cost of the noble metal catalyst, Mn-Co-O composite oxide catalysts were synthesized by liquid-phase mixed solid phase calcination method, and their activity was much higher than that of single M _ S _ O _ s _ 2 and Cos _ 3O _ 4 prepared by the same method. When the molar ratio of Mn/Co was 1 and the calcination temperature was 400 鈩，

本文編號：1548057