褐煤的高效氧化解聚及其在高效减水剂合成中应用基础研究

The disadvantages of lignite, such as high moisture content, low calorific value, easy self-ignition et al., seriously impede its high-efficiency utilization. Meanwhile, high oxygen content and high reactivity are advantageous to the high-value and resource utilization of lignite. Based on the structural characteristics of lignite, a new technological route of high-efficiency resource utilization of lignite is put forward in this project, which includes the depolymerization of lignite by the oxy-cracking technology in dilute alkali aqueous to obtain aromatic compounds containing abundant of carboxyl and hydroxyl groups, and the synthesis of superplasticizer with these products from the oxy-cracking of lignite. In this project, the influences of oxy-cracking conditions on the structure and composition of products will be investigated by the oxy-cracking experiments of lignite in dilute alkali aqueous and the extraction separation of products. Further, the reactivity of cross-linking structures in lignite and the selectivities of products will also be understood. By the experiments of the oxy-cracking of selected model compounds and the oxy-cracking kinetics of lignite, the mechanism of oxy-cracking of lignite will be discussed, and the key factor to influences the structure and composition of oxy-cracking products of lignite will also be disclosed. Through the synthesis and performance assessment of superplasticizer, the influences of structure of oxy-cracking products on the performances of synthesized superplasticizer will be investigated, and the structure-activity relationship between oxy-cracking products and the performance of synthesized superplasticizer will also be disclosed. Finally, the regulation mechanism of the oxy-cracking of lignite, which provides the synthetic raw material of superplasticizer, will be built in this project. Based on the research of this project, a new technology combined the oxy-cracking of lignite with the synthesis of superplasticizer will be developed. It will also provide the theoretical and technical support for the preparation of high added value fine chemical from lignite.

高水分、低热值、易自燃的褐煤特性严重制约了褐煤高效利用，但是高含氧量、高反应活性赋予褐煤高值化和资源化利用优势。基于褐煤结构组成特点，本项目提出利用稀碱溶液中液相氧化裂解技术，解聚褐煤大分子，获得富含羧基和羟基的芳香性氧化产物，并应用于高效减水剂合成的褐煤高值化利用技术路线。拟通过弱碱体系中褐煤氧化裂解与产物萃取分离，考察氧化条件对产物结构组成的影响规律，研究褐煤交联结构反应性与产物选择性。结合模型化合物和氧化裂解动力学研究，探索褐煤氧化裂解机理，揭示影响氧化裂解产物结构组成的关键因素。通过高效减水剂的合成与性能评价，研究氧解产物结构对减水剂合成与性能的影响规律，揭示氧解产物结构与高效减水剂应用性能的构效关系，从而形成针对高效减水剂合成的褐煤氧化裂解调控机制。通过本项目研究，预期将建立褐煤液相氧化裂解与高效减水剂合成技术体系，并为褐煤制备高附加值精细化学品提供理论与技术支撑。

基于褐煤结构组成特点，利用褐煤制备混凝土减水剂等大宗精细化学品是廉价褐煤高值化和资源化利用的重要途径。为此，本项目利用液相氧化裂解技术开展了温和条件下褐煤高效氧化裂解性能研究。以煤基腐殖酸为目标产物，考察了煤结构和过程调控对氧化裂解产物结构组成的影响规律，结合热溶预分离研究了影响褐煤大分子氧化裂解的结构因素，探索褐煤氧化裂解机理。然后，结合煤基腐殖酸结构表征，开展了混凝土高效减水剂的合成与性能评价，研究了腐殖酸结构与高效减水剂应用性能的构效关系与调控机制。. 研究结果表明：通过褐煤液相氧化裂解可以高收率制备煤基腐殖酸，且反应条件温和、碱消耗量低、利用效率高。其中，锡林郭勒褐煤80℃、煤碱比=3条件下腐殖酸收率最高可达85 %，同时CO2收率仅为0.2 %。亚甲基、醚键等C-C和C-O桥键交联结构是影响褐煤氧化裂解的关键结构因素，氧化裂解体系的氧化能力是产物结构和组成的主要因素。相对于煤结构解聚，腐殖酸氧化裂解活化能高，选择温度、氧气分压等氧化裂解反应条件可以调控腐殖酸结构和选择性。低于煤热解温度下的热溶可以有效分离出煤中小分子相，同时获得具有良好液相氧化裂解活性的热溶萃余煤。温和热溶与热溶萃余煤氧化解聚相结合，可以为褐煤分级转化与分质利用提供新的途径。氧化裂解腐殖酸芳香度高，羧基、羟基等含氧官能团丰富，并存在一定量的桥键结构，具有良好的磺甲基化、羟甲基化和缩合反应活性。通过磺甲基化缩合与接枝共聚可以制备具有高效减水性能的混凝土减水剂，实现氧化裂解腐殖酸高值化利用和高效减水剂低成本制备。其中，煤基腐殖酸支链化结构和羧基、酚羟基等含氧官能团是影响减水剂吸附和分散性能的主要结构因素。同时，氧化裂解腐殖酸也可以用于碳聚点等功能碳材料制备。基于上述研究，完成了计划书所有内容研究，实现了相应研究目标，相关研究成果可以为褐煤高值化利用与煤基精细化学品开发提供重要的理论与技术支撑。