还原烟气中硫物种的催化转化及资源化应用基础研究

It is of great urgency to govern the sulfur pollution from industrial gas because of its harmfulness to humans and the environment. At present, the studies about the removal and resources reuse of sulfur species contained in reducing industrial gas (H2S,CS2 and COS) are relatively weak,compared to those of SOx compounds in oxidizing industrial gas. Most of the reducing industrial gas is dealt with direct combustion after a simple washing with water and caustic, thus resulting in low reuse value. Therefore, there is a great demand for advanced techniques.In this project, metal sulfide-based catalysts are used to simultaneously catalyze the hydrogenation of CS2 to CH3SH+H2S, the hydrogenation of COS to CO+H2S and the decomposition of H2S to S+H2, as a result, the synergistic removal and resource utilization of sulfur species in reducing industrial gas are achieved. Mesoporous materials are the ideal supports for metal sulfide-based catalysts employed in these reactions, due to their ordered pore structure, large surface area and controllable characteristics for surface physical-chemical properties. In addition, the selection of promoters, synthesis method and post-treatment process, which plays an important role in the catalytic performance, is studied carefully. Numerous advanced techniques, such as XRD, TEM, XPS, TPR, et al., are used to characterize the catalysts to reveal the relationship between synthesis, properties and catalytic performances. The modulation of catalytic activity center, the mechanism of synergistic removal of sulfur species and the correlations are discussed. This research provide reliable theory and technical basis for the synergistic removal and resource utilization of sulfur species in reducing industrial gas.

工业烟气中的硫物种是导致空气质量恶化的重要污染源之一。相对于氧化性工业烟气，还原烟气中硫物种（H2S，CS2和COS）脱除和资源化利用的研究相对薄弱。本项目拟采用比表面大、孔道规整的有序介孔材料为催化剂载体，制备高性能负载型金属硫化物催化剂。通过实现H2S和H2的循环利用，促进硫物种（H2S，CS2和COS）的高效协同催化转化和CO的生成，不仅可获得国内紧缺的硫磺和甲硫醇，而且有利用CO2减排。本研究在催化剂活性评价、动力学研究、物化性能与微观结构表征的基础上，探索催化剂活性中心的调变规律，构建催化剂结构与活性之间的构效关系，揭示还原气氛条件下H2S，CS2和COS协同脱除的反应机理。该项研究的开展将为还原烟气中硫物种的协同脱除与资源化利用提供可靠的理论依据。

本项目以还原烟气中硫物种的催化转化合成甲硫醇为研究目标，通过对载体、制备方法、助剂的筛选与优化，后续硫化过程等，研制了系列高性能的Mo基催化剂。项目主要考察了COS(CS2)/H2S/H2反应体系合成甲硫醇的情况，并结合项目进展情况和还原烟气中存在大量CO的事实，扩展研究了CO/H2S/H2合成甲硫醇的反应体系，并在考虑到甲硫醇低沸有毒性的基础上对后端甲硫醇的催化降解也进行了考察，以确保整个实验过程的安全性。项目系统研究了反应温度、空速、压力等实验条件等对硫物种转化率及甲硫醇选择性的影响；并利用了XRD、BET、XPS、TEM、SEM、TPR、H2S-TPS、TPD、TPO等现代物理化学表征手段对催化剂的微观结构和表面性质进行深入细致考察，研究了催化剂合成条件与参数对其物理化学性质的影响，并与催化性能进行关联，探讨了催化剂活性中心的调变规律。在催化剂活性评价的基础上，分别进行中间产物加氢研究，并结合热力学、动力学以及理论计算，对Mo基催化剂上硫物种的作用机制、甲硫醇的合成机理进行了探索和考察，提出了COS/H2S/H2、CS2/H2S/H2、CO/H2S/H2合成甲硫醇的反应路径。.研究表明，载体对催化剂的性能影响较大，Al2O3载体在COS(CS2)/H2S/H2体系中表现最佳，而SBA-15则在CO/H2S/H2体系中表现优异；助剂（La，K等）的添加有利于减弱Mo与载体的相互作用，使硫化后形成更多的活性MoS2相，从而极大提高了Mo基催化剂的催化性能，而活性组分Mo和助剂的浸渍顺序对催化性能也影响较大，共浸渍方法效果更佳。项目组研制的La-Mo/Al2O3催化剂在COS/H2S/H2体系中对甲硫醇的选择性超过70%， Mo-K/SBA-15催化剂在CO/H2S/H2体系中对甲硫醇的选择性超过60%，明显优于文献报道的其他催化剂。研究证实了COS既可直接加氢合成甲硫醇，又能歧化生成CS2，CS2进一步加氢快速合成甲硫醇。项目研究成果不仅为还原性烟气中硫物种的协同高值资源化利用提供了重要的实验数据和理论基础，而且为还原烟气中碳资源的利用提供参考，同时为甲硫醇工业化生产提供技术支撑。已发表学术论文16篇，其中SCI收录14篇；申请发明专利3项。培养研究生5名。