基于Schiff碱式双功能脱硫剂的焦炉煤气脱硫集成工艺研究

Strengthening the comprehensive utilization of coking gas is the necessary channel for coking industry to realize energy-saving and emission-reduction and the sustainable development. The important precondition is to develop the desulfurzation technology with high efficency and without pollution. According to the fact that the desulfurizing reaction was only carried out in regeneration tower during PDS desulfurizing technology, and the fact that mass sulfur foam produced by H2S oxidation severely inhibited the catalytic removal of organic sulfur and the regeneration efficiency of desulfurized solution, accompanying with high amount of secondary salt, task-specific ionic liquid desulfurizers would be constructed by the reaction of Schiff base Co or Fe complex with Fe-based ionic liquid, and two-stage wet intergrated desulfurization technology would be established by first oxidation removal of H2S catalyzed by inorganic Fe reactivity center and then by removal of mercaptan (as the representative of organic sulfur) catalyzed by Schiff base Co or Fe complex cationic reactivity center, to improve the efficiency of mercaptan removal and the regeneration efficiency of desulfurized solution and to avoid producing secondary salt. The kinetics of H2S oxidation catalyzed by inorganic Fe reactivity center would be established, and the kinetic model of mercaptan removal catalyzed by Schiff base Co or Fe complex cationic center would also be established, and the synergistic mechanism of bimetal reactivity centers would be revealed, and the process control parameters would be optimized. The foundation of thesis and application would be laid to establish and optimize two-stage wet catalysis-oxidation intergrated desulfurization technology, and the sustainable development of coking industry would be promoted.

加强我国焦炉煤气综合利用是实现焦化工业节能减排和可持续发展的必要途径，而其中重要前提是发展高效无污染的脱硫技术。针对我国焦炉煤气脱硫采用PDS湿法氧化法脱硫技术中，脱硫反应仅在再生塔中进行，由H2S氧化产生的大量硫磺泡沫严重抑制有机硫的催化脱除和脱硫液再生效率，并伴随副盐高的问题，本项目通过Schiff碱Co或Fe络合物与Fe基离子液体反应构建双功能离子液体脱硫剂，建立先由无机Fe阴离子中心氧化脱除H2S，再由Schiff碱Co或Fe阳离子中心催化脱除硫醇（有机硫代表）的两段式湿法脱硫集成工艺，以提高硫醇脱硫效率和脱硫液再生效率，并避免副盐产生。建立无机Fe活性中心氧化H2S的动力学，及Schiff碱Co或Fe活性中心催化脱除硫醇的动力学模型，揭示双金属反应活性中心的协同机理，优化过程控制参数，为确立并优化两段式湿法催化氧化脱硫集成工艺奠定理论及应用方面基础，推动我国焦化工业可持续发展。

加强我国焦炉煤气综合利用是实现焦化工业节能减排和可持续发展的必要途径，而其中重要前提是发展高效无污染的脱硫技术。焦炉煤气中硫的存在形态多样，面对日益严格的环保要求，急需开发能同时脱除有机硫和无机硫的技术及药剂，实现焦炉煤气中含硫污染物的高效深度脱除。.本课题系统研究了铁基咪唑离子液体对硫化氢的脱除性能，其脱硫率可达99%以上，硫容高达0.31 g •L – 1，氧化脱硫过程中无须添加辅助试剂和调控p H 值，脱硫后可以在氧气中再生并循环使用。研究还发现添加中性或弱碱性溶剂可以适当降低铁基离子液体的酸性，促进H2S的溶解吸收，推动气液传质过程，使脱硫性能大大提高。Schiff碱过渡金属配合物具有载氧功能，采用“瓶中造船”合成方法成功制备了NaY分子筛为载体的负载型希夫碱钴配合物催化剂Co(salen)Y。该催化剂对高浓度和低浓度的噻吩均有较高的去除效果，180 min可将初始浓度为500ppm的噻吩降到1ppm，噻吩完全被氧化为硫酸根离子。主要是由于Schiff碱钴配合物本身具有很好的氧合性能，载体分子筛又能显著提高Schiff碱配合物的催化性能和稳定性，避免Schiff碱配合物在反应过程中降解和形成二聚或多聚反应，实现催化剂的循环利用。在此基础上发展的双金属配合物体系在氧化DBT过程中体现了较好的协同作用，双金属催化剂(Cu-Co)(salen)Y对二苯并噻吩的脱除率可达97.6 %。基于上述对铁基离子液体和Schiff碱过渡金属配合物的认识，构建双功能离子液体脱硫剂，建立了先由无机Fe阴离子活性中心氧化脱除无机硫H2S，再由Schiff碱金属阳离子活性中心催化脱除有机硫的两段式湿法脱硫新工艺。