含氯煤基固体酸的制备及其纤维素水解的研究

发布时间：2018-06-29 18:51

本文选题：煤 + 氯化　；参考：《太原理工大学》2017年硕士论文

【摘要】：纤维素是一种廉价易得、储量丰富的可再生资源,是由D-葡萄糖单体彼此通过β-1,4糖苷键连接而成的线性高分子化合物。纤维素传统的水解方法主要是液体酸和酶水解,但其造成的设备腐蚀、产物不易分离、价格昂贵都限制了它的应用。为了克服上述存在的问题,近些年来碳基固体酸被用于纤维素的高效水解。将大分子煤与碳基固体酸的结构对比不难发现,煤中除没有-SO_3H外,具备了碳基固体酸所有的结构特征,这意味着煤具有制备碳基固体酸的基因优势。我们以煤为原料,试图在传统碳基固体酸上引入电负性较强的氯原子,制备出氯功能化煤基固体酸,打破纤维素羟基之间的氢键,促进纤维素水解。实验主要改变煤种的粘结性、氯化方法、氯化剂以及三氯乙酸比例等变量制备煤基固体酸并将其应用到纤维素水解。通过扫描电镜(SEM)、拉曼光谱(Raman spectrum)、比表面积(BET)、X射线衍射(XRD)、红外光谱(FT-IR)、X射线电子能谱(XPS)等手段来分析煤基固体酸的结构和表面元素含量,通过测定酸性基团密度、纤维二糖吸附量和还原糖得率来考察煤基固体酸的催化性能。探究了催化剂结构、表面活性官能团在纤维素水解过程中的作用机理,实现不同活性官能团之间的有效整合。将四种粘结性不同的煤作为碳源,通过和三氯乙酸共炭化-磺化的方法制备出四种煤基固体酸,探索碳源的原料组成—催化剂结构—纤维素水解性能之间的构效关系。结果发现,高粘结性煤制备煤基固体酸的芳香碳片层在空间的排列更加不规整,无序度更大,有更多的缺陷位,芳香碳片层边缘负载更多的-COOH基团,总酸密度较大,吸附能力和水解活性也较大。以粘结性较大的交口肥煤(JKFM)为碳源,采用三种不同的氯化方法制备出三种不同的煤基固体酸。结果发现,氯以共价键的形式直接连在煤基固体酸芳香碳片层的边缘,催化剂中的S主要以氧化态(-C-SO_x-)磺酸基团和非氧化态(C-S-C)噻吩硫的形式存在。共炭化—磺化制备煤基固体酸(SH-SO_3H)的芳香碳片层在空间的排列更加规整,芳环缩合程度更大,-SO_3H基团密度较低,但催化剂SH-SO_3H表面氯基团密度最多,吸附能力、水解活性和催化剂的重复利用性最好。以粘结性较大的交口肥煤为碳源,选择三种不同的氯化剂采用共炭化—磺化的方法制备出三种煤基固体酸。结果发现,交口肥煤和不同氯化剂在共炭化时发生相互作用,在芳香碳片层的边缘负载了共价键氯基团,而且在催化剂表面碳、氧、硫、氯四种元素分布地非常均匀。氯化后制备的煤基固体酸芳香碳片层在空间的排列更加规整,芳香度变大,芳香片层直径变大,氯化剂的不同对固体酸表面负载氯基团的含量影响很大,其中以三氯乙酸为氯化剂制备的煤基固体酸芳香碳片层上氯的负载量最大,催化剂的吸附能力和水解性能最好。考察了氯化剂不同比例对煤基固体酸结构和性能的影响。结果发现,氯化剂的添加量不同对制备固体酸表面活性官能团的负载量有很大影响。随着三氯乙酸比例的增大,-Cl基团密度增大,而-SO_3H基团密度下降,-COOH基团密度略有增加,-OH密度变化很小。固体酸对纤维二糖的吸附量与-Cl基团密度变化趋势一致,说明催化剂表面负载氯基团的存在有利于提高吸附能力。
[Abstract]:Cellulose is a cheap and readily available and abundant renewable resource. It is a linear polymer composed of D- glucose monomers connected to each other through the glucoside bond of beta -1,4. The traditional hydrolysis method of cellulose is mainly liquid acid and enzyme hydrolysis, but the equipment corrosion, the product is not easy to separate, and the price is expensive to limit its application. In order to overcome the above problems, carbon based solid acids have been used in the efficient hydrolysis of cellulose in recent years. Comparing the structure of large molecular coal with carbon based solid acids, it is not difficult to find that the coal has all the structural characteristics of carbon based solid acids in addition to -SO_3H, which means that coal has the genetic advantage of preparing carbon based solid acids. As raw materials, it is intended to introduce a strong electronegative chlorine atom on the traditional carbon based solid acid, to prepare the chlorinated functionalized coal based solid acids, break the hydrogen bonds between the hydroxyl groups of the cellulose and promote the hydrolysis of cellulose. The experiment mainly changes the adhesion of coal, the chlorination method, the chlorination agent and the proportion of three chloroacetic acid are used to prepare the coal based solid acids and should be used for the preparation of coal based solid acids. Using scanning electron microscopy (SEM), Raman spectroscopy (Raman spectrum), specific surface area (BET), X ray diffraction (XRD), infrared spectroscopy (FT-IR), X ray electron spectroscopy (XPS), and other means to analyze the structure and surface element content of coal based solid acids, by measuring the density of acid group, the adsorption amount of fiber two sugar and the yield of reducing sugar The catalytic properties of coal based solid acids are investigated. The mechanism of the catalyst structure, the action mechanism of the surface active functional groups in the hydrolysis of cellulose and the effective integration of different active functional groups are realized. Four kinds of coal with different cohesiveness are used as carbon sources to prepare four kinds of coal based solid acids by CO carbonization and sulfonation of three chloroacetic acid and explore carbon. The structure effect relationship between the raw material of the source - the structure of the catalyst - the hydrolysis property of cellulose has been found. The results show that the arrangement of aromatic carbon layers of coal based solid acids in high bond coal is more irregular in space, with greater disorder degree, more defect positions, more -COOH groups on the edge of the aromatic carbon layer, and the total acid density is larger, and the adsorption energy is higher. The force and hydrolysis activity are also large. Three different coal based solid acids are prepared by three different chlorination methods with three different chlorination methods. The results show that chlorine is directly linked to the edge of the aromatic carbon layer of coal based solid acid in the form of covalent bond, and the S in the catalyst is mainly oxidized by the -C-SO_x- sulfonic acid group. The form of non oxidative state (C-S-C) thiophene sulphur exists. The aromatic carbon lamelles of CO carbonization and sulfonation of coal based solid acid (SH-SO_3H) are more orderly in the arrangement of the space, the degree of aromatic ring condensation is greater, the density of the -SO_3H group is lower, but the density of the chloride Group on the surface of the catalyst SH-SO_3H is the most, the adsorption capacity, the hydrolysis activity and the reutilization of the catalyst are the most. Three kinds of coal based solid acids were prepared by three different kinds of chlorination agents using CO carbonization and sulfonation. The results showed that the interaction between the mixed coal and the different chlorination agents in the carbonization was negatively loaded with the covalent chloride group on the edge of the aromatic carbon layer, and the surface of the catalyst was on the surface of the catalyst. The four elements of carbon, oxygen, sulfur and chlorine are very evenly distributed. The arrangement of the coal based solid acid aromatic carbon lamellae after chlorination is more regular, the aromatic degree becomes larger, the diameter of the aromatic layer is larger, the different chlorination agents have a great influence on the content of the chlorine groups on the surface of the solid acid, and the coal based solid acid prepared with the chloroacetic acid as the chlorination agent is three chloroacetic acid. The load of chlorine on the aromatic carbon layer is the largest, the adsorption capacity and the hydrolysis performance of the catalyst are the best. The effects of the different proportion of the chlorination agent on the structure and properties of the coal based solid acid are investigated. The results show that the addition of the chlorination agent has a great influence on the load of the solid acid surface active functional group. With the increase of the proportion of three chloroacetic acid, The density of -Cl group increased, the density of -SO_3H group decreased, the density of -COOH group increased slightly, and the density of -OH changed little. The adsorption capacity of solid acid on fiber two sugar was the same as that of -Cl group density, indicating that the presence of the chlorine group on the surface of the catalyst was beneficial to the improvement of the adsorption energy.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ530;TQ352.78

【参考文献】