离子液体催化二甲基呋喃温和转化合成对二甲苯
发布时间：2019-03-06 08:13
【摘要】：芳香族化合物在化学合成与工业制造领域有着广泛应用。目前,它们主要由石油、煤炭等不可再生资源生产,从可再生资源制造芳香族化合物可以降低对化石资源的依赖并减轻环境负荷。生物质是一种环境友好的可再生资源,以生物基原料制备芳香族化合物是生物质转化生产基础化学品的重要途径之一。开发步骤简单、选择性高、反应条件温和的高效催化体系对实现生物质转化的工业化利用具有重大意义。本研究在温和条件下,分别以三氟甲磺酸盐和酸性离子液体为催化剂,成功实现由生物质基呋喃类化合物与丙烯酸到芳香族化合物的一步转化。首先以三氟甲磺酸盐为催化剂,离子液体为溶剂,以2,5-二甲基呋喃和丙烯酸为原料制备对二甲苯。结果表明,Sc(OTf)3和[Emim]NTf2组成最优的反应催化体系,在强化脱水过程和引入脱羧步骤后,2,5-二甲基呋喃的转化率为90%,芳香族产物的选择性为78%。[Emim]NTf2作为溶剂有效地促进了反应,降低了催化剂用量并提高了产物选择性,同时,该催化体系也可以有效催化顺丁烯二酸酐作为亲二烯体的反应。然而,三氟甲磺酸盐催化体系中副反应较多,产物选择性有待提高。酸性离子液体兼具酸性催化活性位点与离子液体作为溶剂的优良特性,以其同时作为催化剂和溶剂有望构建一个更为简单高效的催化体系。经过对一系列酸性离子液体的筛选,[Bmim]HSO4可在常温常压下催化2,5-二甲基呋喃和丙烯酸反应生成对二甲苯和2,5-二甲基苯甲酸,在87%的2,5-二甲基呋喃转化率下,芳香族产物选择性可达89%,在脱羧反应后对二甲苯的选择性可达84%。为了深入研究反应机理,通过13C同位素示踪实验和分子模拟进一步验证了反应机理的可靠性,并揭示了最低能垒反应路径。此外,以不同呋喃类化合物与亲二烯体为原料,发现呋喃环上的供电子甲基对脱水和脱羧过程起到关键活化作用,在调节离子液体的结构和酸强度后,得到一系列中等收率的芳香族产物。因此,这两种方法为生物基呋喃转化制芳香族化合物提供了可能的通用方法,随着对催化体系的不断改善,由生物质衍生的原料获得工业芳香族产品的路线也将具有更高的经济和环境可行性。
[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.
【学位授予单位】：中国科学院大学(中国科学院过程工程研究所)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ241.13
本文编号：2435355
[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.
【学位授予单位】：中国科学院大学(中国科学院过程工程研究所)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ241.13
【参考文献】
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1 邹琥;吴巍;葸雷;朱宁;史军军;;甲醇制芳烃研究进展[J];石油学报(石油加工);2013年03期
，本文编号：2435355
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