抑制剂作用下烧结过程NOx原位催化减排机理及过程调控机制研究

The amount of NOx emitted in iron ore sintering is very large and the concentration is very low, which lead to its treatment is very difficult. By catalyzing the reaction of coke-NO and CO+NO during the sintering process, NOx emissions can be controlled from the source. This project aims at in situ catalytic reduction of NOx in the sintering process. CeO2, mill scale and Cu/ZSM-5 are used to catalyze NO reduction in the sintering process. This project studies the effect of modification of coke on NOx emission in coke combustion, the effect of the composition, structure on the reaction of CO + NO and NO and CO adsorption and reaction behavior on modified coke and Ca-Fe composites. The project includes researches on the mechanism of NOx catalytic reduction in coke combustion process, the active site, structure and action conditions of Ca-Fe complex for NOx reduction and the mechanism of NOx reduction in the addition of Cu/ZSM-5 during sintering. Furthermore, the effect of NOx reduction through modification of coke and the addition of mill scale and Cu/ZSM-5 simultaneously during sintering will be studied, and the process control mechanism of NOx in-situ catalytic reduction during sintering will be revealed. The study of this project is expected to provide a basis for the development of NOx reduction technology from the source for iron ore sintering process.

铁矿石烧结过程废气排放量大、废气中NOx浓度低导致处理难度大，通过抑制剂来催化烧结过程中焦炭-NO和CO+NO反应，可从源头上控制NOx排放。项目以烧结过程NOx原位催化减排为目标，拟利用CeO2改性焦炭、氧化铁皮和Cu/ZSM-5添加对烧结过程NOx原位催化，重点研究抑制剂对焦炭燃烧过程NOx释放影响、Ca-Fe复合物组成和结构对CO+NO反应的影响及Cu/ZSM-5减排NOx的作用、NO和CO在改性焦炭和Ca-Fe复合物上吸附和反应行为，揭示抑制剂催化焦炭燃烧过程NOx减排机理、Ca-Fe复合物催化CO+NO反应的活性位、结构和作用条件及Cu/ZSM-5添加烧结过程NOx减排机理。进而研究改性焦炭协同氧化铁皮及Cu/ZSM-5添加的烧结过程NOx减排规律和作用条件，揭示抑制剂作用下烧结过程NOx原位催化减排的过程调控机制。本项目的研究为烧结从源头上减排NOx技术的开发提供研究基础。

铁矿石烧结过程产生的NOx排放量大、浓度低导致处理难度大。NO主要来自作为燃料含氮焦炭的燃烧，通过开发新型抑制剂可实现煤/焦催化燃烧和烧结过程NOx原位减排。本项目主要研究了抑制剂对焦炭燃烧过程NOx释放影响、Ca-Fe复合物组成和结构对焦炭燃烧、烧结过程及NO减排反应的影响、Cu/ZSM-5对焦炭燃烧和烧结原位减NOx作用、焦炭改性、氧化铁皮及氧化铁皮-CaO对烧结过程NO原位减排的性能。发现CeO2、Cu-ZSM-5、Fe、FeO、Fe3O4、Fe2O3、氧化铁皮、氧化铁皮-CaO复合物等对焦炭燃烧具有催化燃烧和NO原位减排性能，铁的价态和燃烧过程中结构与组成显著影响NO减排性能。2%Fe-4%CeO2、2%Fe-10%CaO和2%Fe2O3-2%CeO2的NO减排性能最佳，NO减排65%以上，Fe基催化剂添加可显著提高NO在焦炭/催化剂表面的吸附。烧结杯试验过程中2%CeO2的添加可减排25.3%NO，烧结矿的成品率变化不大、转鼓强度有所提高。氧化铁皮改性焦炭可使微烧结过程NO减排18%。Cu-ZSM-5烧结杯验证实验中发现没有NO减排性能。4-10％CaO和2％Fe可使焦炭的燃烧指数和燃尽指数分别提高1.4倍和1.9倍。2％Fe-10％CaO和2％Fe-4％CeO2可使NO分别减排38.4％和39.6％。Fe和Fe3O4可以同时促进NO的分解以及C-NO和NO-CO的反应。6%Fe3O4添加可使NO减排60%；4％CaO-2％Fe3O4可使焦炭着火指数和燃尽指数分别提高1.6和1.7倍。6%氧化铁皮添加可使焦炭焦炭着火指数和燃尽指数分别提高1.2和1.5倍，NO减排31.4%。氧化铁皮-CaO可以加速焦炭燃烧，并同时减少SO2和NO的排放。氧化铁皮-CaO复合材料中氧化铁皮和CaO含量的增加可以分别提高NO和SO2减排性能。4%氧化铁皮-2%CaO可使焦炭燃烧过程中NO和SO2分别减排35%和25%。NO减排活性主要归因于氧化铁皮-CaO中的Fe2O3和燃烧过程中形成的Ca2Fe2O5，SO2减排源于CaO固硫。氧化铁皮-CaO中氧化铁皮含量的增加导致灰渣颗粒的增大。Ca-Fe复合物在焦炭的催化燃烧和铁矿石烧结过程中原位还原NO方面具有较大应用潜力。