多孔酸碱催化剂一步催化转化纤维素制备5-羟甲基糠醛的研究

发布时间：2018-09-03 20:31

【摘要】：随着对全球变暖和化石能源可用率的降低,可再生化学品和能源的制备已经引起世界各国的关注。其中,具有资源丰富、可再生和低污染特性的生物质被认为是最有前途的能源替代品之一。5-羟甲基糠醛(HMF)被鉴定为全能的中间增值化学品和高性能液体燃料。催化剂在由生物质转化为HMF过程中扮演着至关重要的角色。为了改善一步转化纤维素到HMF的可持续性、提高羟甲基糠醛选择性、催化剂活性、耐久性和易于从反应介质中分离,开发新颖的催化体系迫在眉睫。多孔固体催化剂具有比表面积大、孔隙率高、对设备腐蚀性小和易与产品分离等优点,是一种理想的催化剂。本论文旨在提高转化纤维素制备HMF的效率,合成了三类多孔固体催化剂,并详细研究了其催化性能。详细研究内容如下:(1)酸碱双功能介孔催化剂的制备及其一步催化纤维素制备5-羟甲基糠醛的研究以十六烷基三甲基溴化铵(CTAB)为模板,正硅酸四乙酯(TEOS)为原料,以NH4F为催化剂,碱性条件下,利用水热法制备具有六方孔道的介孔纳米二氧化硅材料(Mesoporous silica nanoparticles,MSNs)。然后,通过修饰法分别将磺酸基(-SO3H)和氨基(-NH2)接枝到MSNs的内外表面上,即合成酸碱双功能的介孔催化剂。为了探究酸碱活性位点在一步催化纤维素制备HMF中的作用,合成仅具有酸性位点的介孔催化剂和仅具有碱性位点的介孔催化剂。此外,该催化剂还分别用来催化葡萄糖和果糖制备HMF。最后,对此催化剂的再生性进行探讨。(2)酸碱双功能的多级孔催化剂的制备及其一步催化纤维素制备5-羟甲基糠醛的研究以少量的Hypermer 2296为乳化剂,偶氮二异丁腈为引发剂,二乙烯基苯和甲基丙烯酸缩水甘油基酯为单体,通过W/O高内相乳液(High Internal Phase Emulsions,HIPEs)模板法制备了多孔泡沫聚合物(Porous polymers,PHs)。然后,利用化学方法使酸碱双功能的介孔二氧化硅纳米粒子(MSNs-SO3H-NH2)和PHs相结合。浓硫酸磺化后,便得到具备多级孔结构的酸碱双功能催化剂(SPHs@MSNs-SO3H-NH2)。此催化剂应用于转化纤维素、葡萄糖和果糖制备增值化学品HMF。(3)Br?nsted-Lewis双酸性位点的多级孔催化剂的制备及其一步催化纤维素制备5-羟甲基糠醛的研究通过凝胶-乳胶法将正丙醇锆(Zr Pr)嫁接到表面羟基化的硅球模板上,将样品浸泡在硫酸溶液中以引入磺酸基团,最后高温煅烧得具有超强酸表面的磺化ZrO_2纳米材料(Super acidic surface,SZs)。然后,以SZs为稳定粒子,少量的Tween85为乳化剂成功制备了水包油(O/W)Pickering HIPEs。最后,通过离子交换反应法,将Br?nsted酸性位点结合到材料表面,由此合成Br?nsted-Lewis双酸性位点的多级孔泡沫催化剂(Hierarchical pore foam catalysts,HPFCs)。此催化性能应用于一步将纤维素、葡萄糖和果糖转化制备HMF。
[Abstract]:With the decrease of global warming and fossil energy availability, the preparation of renewable chemicals and energy has attracted worldwide attention. Among them, biomass with rich resources, renewable and low pollution characteristics is considered as one of the most promising energy alternatives. 5- hydroxymethyl furfural (HMF) has been identified as a versatile intermediate value-added chemical and high performance liquid fuel. Catalysts play an important role in the process of conversion from biomass to HMF. In order to improve the sustainability of one-step conversion of cellulose to HMF, enhance the selectivity of hydroxymethyl furfural, the activity of catalyst, durability and easy separation from reaction medium, it is urgent to develop novel catalytic system. Porous solid catalyst is an ideal catalyst because of its large specific surface area, high porosity, low corrosion to equipment and easy separation from the product. In this paper, three kinds of porous solid catalysts were synthesized to improve the efficiency of conversion cellulose to prepare HMF, and their catalytic properties were studied in detail. The main contents are as follows: (1) preparation of acid-base bifunctional mesoporous catalyst and its one-step catalytic synthesis of 5-hydroxymethyl furfural using cetyltrimethylammonium bromide (CTAB) as template, tetraethyl orthosilicate (TEOS) as raw material, and NH4F as catalyst. Mesoporous nano-silica (Mesoporous silica nanoparticles,MSNs) with hexagonal pore channel was prepared by hydrothermal method under alkaline condition. Then, sulfonic acid group (-SO _ 3H) and amino group (-NH _ 2) were grafted onto the inner and outer surface of MSNs by modified method, that is, the mesoporous catalyst with acid-base dual function was synthesized. In order to investigate the role of acid-base active sites in one-step catalytic preparation of HMF from cellulose, mesoporous catalysts with only acidic sites and only basic sites were synthesized. In addition, the catalyst was used to catalyze the preparation of HMF. from glucose and fructose, respectively. Finally, the reproducibility of the catalyst was discussed. (2) the preparation of acid-base multifunctional multiporous catalyst and its one-step catalytic synthesis of 5-hydroxymethylfurfural using a small amount of Hypermer 2296 as emulsifier and azodiisobutyronitrile as initiator, A porous foam polymer (Porous polymers,PHs) was prepared by using divinylbenzene and glycidyl methacrylate as monomers. The porous foam polymer (Porous polymers,PHs) was prepared by W / O high internal phase emulsion (High Internal Phase Emulsions,HIPEs) template method. Then, the acid-base bifunctional mesoporous silica nanoparticles (MSNs-SO3H-NH2) and PHs were combined by chemical method. After sulphonation of concentrated sulfuric acid, acid and base bifunctional catalysts (SPHs@MSNs-SO3H-NH2) with multilevel pore structure were obtained. This catalyst is used to convert cellulose, Preparation of HMF. (3) Br?nsted-Lewis double Acid site Multi-pore Catalysts for preparation of glucose and fructose; preparation of 5-hydroxymethylfurfural by one step Catalysis of Cellulose; grafted (Zr Pr) of n-propanol Zirconium onto Surface hydroxyl by Gel-Emulsion method On the base silicon sphere template, The sample was immersed in sulfuric acid solution to introduce sulfonic group and finally calcined at high temperature to obtain sulfonated ZrO_2 nanomaterials (Super acidic surface,SZs with super acid surface. Then, using SZs as stable particle and a small amount of Tween85 as emulsifier, the oil in water (O / W) Pickering HIPEs.) was prepared successfully. Finally, the Br?nsted acidic sites were bound to the surface of the materials by ion exchange reaction, and the multilevel porous foam catalyst (Hierarchical pore foam catalysts,HPFCs) was synthesized by the synthesis of Br?nsted-Lewis double acidic sites. This catalytic activity was applied to the one-step conversion of cellulose, glucose and fructose to HMF..
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ251.11

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