新型复合氧化物修饰的活性炭脱除焦化烟气中SO2、NOx及再生机理研究

This project is aimed at the characteristics of coking flue gas, combined with the performance of activated carbons and of transition metal composite oxides, new composite oxides modified activated carbon was prepared by blending to remove SO2 and NOx in coking flue gas and can realize recycling use of sulfur. It uses the structure unit, morphology and composition of compound oxides containing cerium, manganese, and iron to modify the physical and chemical properties of the composites, and the structure of the porous carbon material and the pore structure were designed, cut and integrated. The shape, structure and electronic properties of the composite oxide were stabilized by the geometrical and electronic binding properties of the porous carbon channel. These are to establish optimal control mechanism of pore structure, electron structure, surface functional group and active center of activated carbon modified by compound oxide. The relationship between compound oxide, activated carbon and catalytic reaction mechanism are clearified, and the influence factors and action mechanism of deactivation and the regeneration technology of deactivated catalyst are studied. They are used to optimize catalyst structure and formulation to improve catalyst activity and lifetime. The influence factors of catalyst on the operation of deSOx and deNOx were studied, and the main parameters of reactor design were found out. The influence law of catalytic desulfurization and denitration is clarified by analyzing different components of composite oxides and pore structure to build optimization regulation mechanism of composite oxide on pore structure, surface functional groups and active center of the activated carbon. The technology path for the deep desulfurization and denitration at low temperature in the coking flue gas will be provided.

本项目针对焦化烟气的特点，结合活性炭与金属复合氧化物的性能，采用共混成型法制备适宜脱除焦化烟气中SO2、NOx并实现硫资源化的复合氧化物修饰的活性炭基脱硫脱硝催化剂。通过含Ce、Mn、Fe等复合氧化物的结构单元组成、形态和组合方式来调控其物理化学性质，并对多孔炭材料形貌和孔隙结构实施定向设计、结构裁剪和功能集成，利用活性炭孔道的几何和电子束缚特性稳定复合氧化物形态、结构和电子性质，构建复合氧化物修饰活性炭的孔隙结构、电子结构、表面官能团和活性中心的优化调控机制；弄清复合氧化物、活性炭与催化反应机理之间的关系，研究催化剂失活影响因素和作用机制以及失活催化剂再生技术，优化催化剂结构与配方，提高催化剂活性和寿命；研究催化剂对脱硫脱硝运行的影响因素，优化反应器设计和工艺，为焦化行业烟气的深度脱硫和低温脱硝新路线提供支撑。

针对焦炉烟气特点，本项目将 Fe、Mn、Ce、Zr、Ti 等进行组合制备成复合氧化物，考察形态、组成、孔隙结构、电子特性、氧化还原性能、酸碱性等的性能，研究复合氧化物添加量、种类、组成对催化剂形成的影响以及对比表面积、孔隙结构、体系尺寸和表面特性等的影响。采用固定床对催化剂进行活性评价，考察活性温度窗口和效率，研究SO2、NOx、O2、NH3和H2O的扩散行为和途径以及在催化剂表面的吸附、裂解和迁移行为，揭示它们的形态转化过程的多路径和多重机制，弄清真正的活性物种，明确反应机理。将复合氧化物性能调控以及催化剂后处理相结合，分析可能发生的变化，考察催化剂活性物种、表面官能团、孔隙等对催化活性的影响规律，设计了反应器，研究再生方式、温度、气氛、次数等对催化剂性能的影响，分析催化剂再生前后活性物种、孔隙、表面特性等变化情况，弄清催化剂恢复脱除SO2、NOx能力的影响因素，构建有效的催化剂再生技术和工艺，为焦化行业烟气的深度脱硫和低温脱硝新工艺、新设备提供支撑。结果表明，焙烧温度影响Mn3O4的暴露晶面，从而在NH3-SCR反应过程中表现出不同的活性，Ti掺杂增加了Ti-Mn复合氧化物的氧空位有利于NO被氧化为NO2，促进了快速SCR反应，提高了低温活性。Mn-Zr共改性的MCM-41分子筛催化剂也能改善N2选择性。改性的La-Mn钙钛矿型复合氧化物脱硝催化剂在120°C时则能实现80%的NOx去除效率，但是超过200°C 时N2选择性变差，非金属F的引入能够提高N2选择性；200°C测试时表现出非常优异的抗硫抗水性，然而硫酸铵盐的形成导致活性下降，但是Ce、Zr的引入能够起到保护Mn活性物种。将用金属氧化物修饰活性炭的脱硫脱硝催化剂，则能改变催化剂上的脱硫活性以及脱硝活性，说明同一炭基催化剂上能够实现脱硫和脱硝。通过改变脱硝装置进气方式，则能有效减少脱硝催化剂中毒而延长催化剂寿命。模块化反应器能够实现连续脱硫。这一系列的研究发现，已发表论文8篇，授权/公开专利5项。