煤基固体酸的结构及其催化纤维素水解的研究

Currently, the raw materials for preparing carbon-based solid acid are confused and lack of relevance. The structure of coal is similar to the carbon-based solid acid except -SO3H, which means coal has great potential to prepare carbon-based solid acid and is superior to other materials. The complexity of the coal structure determines the differences in structure of the solid acid from different coal materials, affecting the performance of cellulose hydrolysis. Under the idea of "integrated" solid acid, the research closely follows the characteristics of coal with rich hydroxyl and high aromaticity, based on the evolution of condensed aromatic ring, alkyl side chain, phenolic hydroxyl group and other oxygen-containing functional groups in the carbonization- sulfonation process, it will be investigated the formation processes of newly discovered mesophase microcrystalline, -CH3 side chain, -Cl and -O-, -OCH2- bridge bond which are different from the conventional solid acid and its influence on the structure of coal-based solid acid. Furthermore, the effects of the structure of coal-based solid acid on adsorption, crystallinity disruption, hydrolytic activity and hydrothermal stability with different hydrolysis substrates will be studied in order to clarify the synergies of different active sites during the hydrolysis process, achieve the effective integration of different active sites, explore the relationship among the chemical composition of raw materials, carbon carrier structure, solid acid structure and the activity of cellulose hydrolysis. It has positive significance to realize high value-added utilization of coal，broaden hydrolysis way of cellulose and achieve simple separation of hydrolysates and enrich the theory of coal chemical and optimal the design of carbon-based solid acid.

目前，制备碳基固体酸的原料纷杂，缺乏针对性。将煤与碳基固体酸的结构对比不难发现，煤中除没有-SO3H外，具备了碳基固体酸所有的结构特征，这意味着煤制备碳基固体酸是极具潜质的，而优于其它碳源。煤的复杂性决定了煤基固体酸结构的差异性，从而影响到水解纤维素性能。在"集成式"固体酸理念的引导下，紧扣煤富羟基高芳香度的特性，从煤中缩合芳环、烷基侧链、酚羟基等含氧官能团在碳化—磺化过程中的演变入手，考察在煤基固体酸上新发现的、区别于传统固体酸的中间相微晶、-CH3等侧链、-Cl和-O-、-OCH2-等桥键的形成过程以及其对煤基固体酸结构的影响，并结合不同水解底物性质，研究煤基固体酸结构对其吸附性、解结晶能力、水解性能的影响，阐明不同功能域在水解中发挥的协同作用，实现不同活性位点有效整合，探索煤结构-碳载体结构-固体酸结构-纤维素水解性能之间构效关系，达到优化设计制备适宜纤维素水解的碳基固体酸的目的。

目前关于制备碳基固体酸的原料纷杂，且这些研究仅把原料作为碳的来源，而忽略了原料化学组成与碳基固体酸结构之间的联系。煤中除没有-SO3H外，具备了碳基固体酸所有的结构特征，煤具有天然的结构优势来制备碳基固体酸。然而，煤组成、结构的复杂性决定了煤基固体酸的差异性。项目首先分别以从褐煤到无烟煤的7种不同变质程度的煤为原料，考察了煤的性质、制备方法等因素对碳基固体酸结构和水解性能的影响。在此基础上，又选择15种煤，重点探讨了在一定的变质程度下，粘结性对碳基固体酸的结构及其催化性能的影响。此外，采用多种氯化方法制备氯功能化煤基固体酸，还通过以模型化合物制备了含硫碳基固体酸，考察了杂原子的引入对碳基固体酸结构和水解性能的影响。研究得到了煤基固体酸详细的结构模型，其结构随着煤种、制备方法和条件的变化而变化。中、低等变质程度，中等粘结性的煤经过特定的碳化温度经两步法制得的煤基固体酸具有较高的催化活性和稳定性，以共价键负载的氯基团有助于打破纤维素羟基之间的氢键，高硫煤中的噻吩硫和亚砜硫对纤维素的吸附水解有积极作用。以上制备的煤基固体酸磺酸基密度高达1.41 mmol/g，还原糖得率可达90%。本项目实现了不同活性位点的有效整合，阐明了不同功能域在水解中发挥的协同作用，探索了煤结构-碳载体结构-固体酸结构-纤维素水解性能之间的构效关系，丰富了煤化学和碳基固体酸的内容，达到优化设计、制备适宜纤维素水解的碳基固体酸的目的。研究结果对拓展煤的高附加值利用，促进生物质的绿色利用技术发展具有重要的科学意义和实用价值。