發(fā)布時間：2019-03-06 08:13

【摘要】：芳香族化合物在化學合成與工業(yè)制造領域有著廣泛應用。目前,它們主要由石油、煤炭等不可再生資源生產(chǎn),從可再生資源制造芳香族化合物可以降低對化石資源的依賴并減輕環(huán)境負荷。生物質是一種環(huán)境友好的可再生資源,以生物基原料制備芳香族化合物是生物質轉化生產(chǎn)基礎化學品的重要途徑之一。開發(fā)步驟簡單、選擇性高、反應條件溫和的高效催化體系對實現(xiàn)生物質轉化的工業(yè)化利用具有重大意義。本研究在溫和條件下,分別以三氟甲磺酸鹽和酸性離子液體為催化劑,成功實現(xiàn)由生物質基呋喃類化合物與丙烯酸到芳香族化合物的一步轉化。首先以三氟甲磺酸鹽為催化劑,離子液體為溶劑,以2,5-二甲基呋喃和丙烯酸為原料制備對二甲苯。結果表明,Sc(OTf)3和[Emim]NTf2組成最優(yōu)的反應催化體系,在強化脫水過程和引入脫羧步驟后,2,5-二甲基呋喃的轉化率為90%,芳香族產(chǎn)物的選擇性為78%。[Emim]NTf2作為溶劑有效地促進了反應,降低了催化劑用量并提高了產(chǎn)物選擇性,同時,該催化體系也可以有效催化順丁烯二酸酐作為親二烯體的反應。然而,三氟甲磺酸鹽催化體系中副反應較多,產(chǎn)物選擇性有待提高。酸性離子液體兼具酸性催化活性位點與離子液體作為溶劑的優(yōu)良特性,以其同時作為催化劑和溶劑有望構建一個更為簡單高效的催化體系。經(jīng)過對一系列酸性離子液體的篩選,[Bmim]HSO4可在常溫常壓下催化2,5-二甲基呋喃和丙烯酸反應生成對二甲苯和2,5-二甲基苯甲酸,在87%的2,5-二甲基呋喃轉化率下,芳香族產(chǎn)物選擇性可達89%,在脫羧反應后對二甲苯的選擇性可達84%。為了深入研究反應機理,通過13C同位素示蹤實驗和分子模擬進一步驗證了反應機理的可靠性,并揭示了最低能壘反應路徑。此外,以不同呋喃類化合物與親二烯體為原料,發(fā)現(xiàn)呋喃環(huán)上的供電子甲基對脫水和脫羧過程起到關鍵活化作用,在調節(jié)離子液體的結構和酸強度后,得到一系列中等收率的芳香族產(chǎn)物。因此,這兩種方法為生物基呋喃轉化制芳香族化合物提供了可能的通用方法,隨著對催化體系的不斷改善,由生物質衍生的原料獲得工業(yè)芳香族產(chǎn)品的路線也將具有更高的經(jīng)濟和環(huán)境可行性。
[Abstract]:Aromatic compounds are widely used in chemical synthesis and industrial manufacture. At present, they are mainly produced by non-renewable resources such as petroleum and coal, and the manufacture of aromatic compounds from renewable resources can reduce the dependence on fossil resources and lighten the environmental load. Biomass is an environmentally friendly renewable resource. The preparation of aromatic compounds from bio-based raw materials is one of the important ways for biomass conversion to produce basic chemicals. It is of great significance to develop an efficient catalytic system with simple steps, high selectivity and mild reaction conditions to realize the industrial utilization of biomass conversion. In this study, trifluoromethanesulfonate and acidic ionic liquids were used as catalysts respectively to achieve one-step conversion from biomass furan to acrylic acid to aromatic compounds under mild conditions. Firstly, p-xylene was prepared from 2,5-dimethyl furan and acrylic acid using trifluoromethanesulfonate as catalyst and ionic liquid as solvent. The results showed that, Sc (OTf) 3 and [Emim] NTf2 formed the optimal reaction catalytic system. After strengthening the dehydration process and introducing decarboxylation step, the conversion of 2,5-dimethyl furan was 90%. The selectivity of aromatic product is 78%. [Emim] NTf2 as solvent can effectively promote the reaction, reduce the amount of catalyst and increase the selectivity of the product. The catalytic system can also effectively catalyze the reaction of maleic anhydride as a dienophile. However, there are many side reactions in the trifluoromethanesulfonate catalytic system, and the selectivity of the products needs to be improved. Acid ionic liquids have the excellent properties of both acidic catalytic active sites and ionic liquids as solvents. It is expected to construct a simpler and more efficient catalytic system by using acid ionic liquids as both catalysts and solvents. After screening a series of acidic ionic liquids, [Bmim] HSO4 can catalyze the reaction of 2,5-dimethyl furan and acrylic acid to p-xylene and 2,5-dimethyl benzoic acid at room temperature and atmospheric pressure. At 87% conversion of 2,5-dimethyl furan, The selectivity of aromatic products can reach 89%, and the selectivity of p-xylene can reach 84% after decarboxylation. In order to further study the reaction mechanism, the reliability of the reaction mechanism was further verified by 13C isotope tracer experiment and molecular simulation, and the lowest energy barrier reaction path was revealed. In addition, using different furan compounds and hydrophilic dienes as raw materials, it was found that the electron-donor methyl on the furan ring played a key role in the dehydration and decarboxylation process, and after adjusting the structure and acid strength of ionic liquids, A series of aromatic products in medium yield were obtained. Therefore, these two methods provide a possible general method for the conversion of biofurans to aromatic compounds, and with the continuous improvement of the catalytic system, The route of obtaining industrial aromatic products from biomass derived raw materials will also have higher economic and environmental feasibility.
【學位授予單位】：中國科學院大學(中國科學院過程工程研究所)
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TQ241.13

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1 鄒琥;吳巍;葸雷;朱寧;史軍軍;;甲醇制芳烴研究進展[J];石油學報(石油加工);2013年03期

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本文編號：2435355