共混活性焦强化低温脱硝及其脱硫脱硝匹配机制研究

In recent years, the activated coke (AC) based flue gas desulfurization and denitrification was widely used. While the denitrification performance of the most AC is generally low, which cannot meet the requirement of the gradually implemented ultra-low emission standard. Therefore, to improve the denitrification activity of AC is the key emphasis of the AC-based, high efficiency, simultaneous flue gas desulfurization and denitrification. In this project, based on the previous desulfurization study of the transition metal blending modified AC, the study on low-temperature catalytic removal of NO was proposed. The relationships between the blending of different transition metals or natural mineral concentrate and the denitrification performance, and the effects of the crystal structure and valence state of the blended metal on the denitrification activity were studied. Then, the multi-metal blending configuration of AC was established, and mechanism of denitrification was described using the physicochemical characterization of AC, coupled with the transient experiments, in-situ Infrared and temperature-programmed desorption-mass spectrometry analysis. At last, the simultaneous desulfurization and denitrification in the moving bed reactor was simulated using a fixed-bed reactor by a cyclic continuous denitrification, desulphurization and regeneration experiment. The NO removal enhancement due to the SO2 removal and regeneration was studied, and the optimum controlling scheme of simultaneous desulfurization and denitrification was constituted. The goal of whole study is to provides the theoretical support and technical guidance of this new blending modified AC in the high efficiency and simultaneous flue gas desulfurization and denitrification.

近年来，活性焦烟气净化技术在我国得到了广泛应用。但当前活性焦的脱硝性能普遍较差，难以满足超低排放对NOx的控制要求。因此，在确保脱硫的前提下强化活性焦脱硝性能是实现活性焦高效同时脱硫脱硝的研究重点。本课题在新型共混活性焦的脱硫研究基础上，拟开展共混活性焦的强化低温脱硝研究，旨在通过不同过渡金属和天然矿物共混与活性焦脱硝关系的构建，形成共混活性焦脱硝的多金属协同配组机制；通过共混金属晶型结构、化学价态和活性焦理化性质对脱硝的作用分析，获得不同金属共混活性焦脱硝活性差异关键因素；通过暂态实验、原位红外和程序升温质谱等技术手段，解析共混活性焦脱硝反应机理。最后，通过连续脱硝-脱硫-再生循环实验，研究移动床反应器中活性焦的同时脱硫脱硝匹配机制，阐述活性焦脱硫再生强化脱硝性能作用机制，建立活性焦高效同时脱硫脱硝优化调控工艺，为新型共混改性活性焦高效协同脱硫脱硝提供理论支持和技术指导。

针对改性活性焦低温SCR脱硝研究较为薄弱的现状，本项目设计采用一步法共混制备金属氧化物改性活性焦催化剂，研究不同过渡金属共混型活性焦低温脱硝性能及其金属配组机制。基于共混改性活性焦催化剂孔隙结构、表面特性、活性组分等理化特征及其脱硝性能，初步建立了共混活性焦脱硝的多金属协同配组机制。研究表明，三金属共混的Cu6-Mn6-Fe1/AC在100 ℃时即获得不74.0%的NO转化率，N2选择性为97.0%。表征分析表明，过渡金属共混使活性焦催化剂表面酸性官能团、吸附氧和晶格氧的含量增加，强化了SCR反应的E-R转化机制而使催化性能得到增强。以天然矿物共混研究了过渡金属配组机制与调控，实现了基于多金属配组机制进一步强化天然矿物改性型活性焦的低温脱硝性能。研究表明，多金属配组机制对天然矿物共混制备高性能活性焦低温脱硝催化剂具有较佳的适用性，基于多金属配组调配可进一步强化天然矿物共混制备的活性焦低温SCR催化性能。模拟研究移动床反应器的脱硝-脱硫-再生工艺过程，探究共混改性活性焦的同时脱硫脱硝匹配机制与调控方案。基于金属配组调配的天然矿物共混改性活性焦具有优异的一体化联合脱硫脱硝性能。金属配组调配的天然矿物共混改性活性焦，结合加热再生设计可以很好的实现低成本高效一体化联合脱硫脱硝。P1/Ti2-15@AC经循环脱硫再生后脱硝活性得到显著提升，第一次和第二次再生后P1/Ti2-15@AC的脱硝NO转化率达到近100.0%，经三次再生后则稳定在85.0%。再生后活性焦脱硫性能降低的原因在于再生后样品微孔减少、介孔增加、表面离域π电子碳和碱性减弱；而表面B酸位量的增加以及少量分硫酸锰与氧化锰的共存使低温脱硝性能显著提升。通过本项目的实施，进一步完善了低成本共混型活性焦低温脱硫脱硝技术体系，为其产业化应用奠定坚实基础。