基于双活性中心调控的改性LDO催化剂低温催化分解NO机理研究

Fluid Catalytic Cracking (FCC) regenerator is an important source of NOx emissions in petrochemical industry in china. However, the application of existing DeNOx technology, such as selective catalytic reduction (SCR), has the disadvantages of increase pressure drop, formation of ABS and corrosion blocking pipeline, safety decline in FCC regenerator flue gas treatment. To develop acceptable DeNOx technology for FCC regenerator flue gas as soon as possible is a key task in response to an important task of national strategy for air pollution prevention and control in China. It also helps protect independent intellectual property rights in the development of DeNOx technology. It would relieve the pressure for the petrochemical industry, that must meet the requirement of environmental standards. Based on the progress of international flue gas DeNOx technology, the aims of this project are developing novel low-temperature catalytic decomposition of NO technology for FCC regenerated flue gas with independent intellectual property rights. Typical conditions of FCC regenerator flue gas is considered in our project. With introduction of alkaline earth metals, rare earth metals and transition metals, layered hydrotalcite materials would be modified. Induced by CO masking effect of oxygen vacancy, great efforts would be done on improving low-temperature NO catalytic activity, sulfur resistance, water vapor resistance, and tolerance to oxygen. The implement of this project will realize the direct reduction of NOx from FCC regenerator flue gas, will meet the increasingly stringent emission standard of air pollutants, and finally provide a novel DeNOx technology for the oil industry flue gas treatment.

催化裂化（FCC）再生器烟气是我国石化行业氮氧化物排放的重要来源，迫切需要进行氮氧化物减排。选择性催化还原法（SCR）等现有脱硝技术应用于FCC再生烟气治理存在气体阻力大，ABS沉积腐蚀阻塞管道，安全性不足等弊端。尽快研发适应我国FCC再生烟气排放特征的脱硝技术，形成具有我国自主知识产权的脱硝核心技术是石化行业应对环保标准提高，响应国家大气污染防治战略的重要任务。本项目立足于国际烟气净化技术前沿，拟以典型FCC再生器烟气为处理对象，通过引入碱土金属、稀土金属和过渡金属元素掺杂改性层状水滑石材料，通过CO诱导效应掩蔽氧空穴，提高低温NO催化分解活性和抗硫抗水蒸气中毒性、耐氧干扰性能，研发具有自主知识产权的FCC再生烟气低温NO催化分解技术，实现FCC再生烟气NOx的直接减排，满足日益严格的大气污染物排放标准要求，为石油化工行业烟气脱硝提供崭新的技术途径。

NO催化分解是一种不产生二次污染的新型脱硝技术，研制开发高效分解NO的催化剂体系是关键。本研究设计研制出了具有层状结构的高效催化分解/还原NO的LDO催化剂。通过掺杂稀土金属、过渡金属等助剂，研究了催化剂双活性中心与低温解离N-O键性能之间的构效关系。探究了烟气中CO气体促进NO催化分解/还原的作用机制。揭示了烟气中O2、HCl、H2O等杂质气体对催化剂的影响，结合氧化还原位-酸碱调控理论，开发出了一系列具有优异耐O2干扰和抗HCl、H2O中毒的脱硝催化剂。.首先，Ce掺杂的Ni-Al-Ox复合氧化物（LDO）催化剂在NO催化还原反应中表现出优异的催化性能。其中，NiAlCe20O催化剂的NO转化效率最高（>95%），掺杂Ce促进了氧空位的生成，利于NO在Ce的氧空位上分解为N2。通过双活性中心调控制备了Ce-Co双金属氧化物催化剂，Ce位点处储存的沉积氧能够提供电子解离N-O键。.其次，Ce-Co-Ox复合氧化物催化剂具有优异的CO-NO反应性能。掺杂Ce提高催化性能主要有两方面原因：一是催化剂比表面积增大，吸附位点数量增加；二是形成的固溶体提升了氧迁移率。反应机理是气态或弱吸附状态的CO与NO的吸附物种反应。不同前驱体和不同制备方法制备的CoCeOx催化剂，其中CoCeOx-TA和CoCeOx-SS在CO-NO反应中表现出良好的催化性能，主要归因于其其优异的还原性、丰富的化学吸附氧和NO吸附位点。.最后，对NO催化分解/还原催化剂的烟气适应性进行了研究。通过改进制备方法降低了催化剂CO和NO的非选择性氧化活性，提升了CeCoOx催化剂的耐O2干扰性能。结合酸碱理论制备具有SiTi壳层的Fe2O3@SiTi催化剂，提升催化剂的酸性，改进了催化剂抗HCl中毒性能。通过P改性促进了催化剂表面氧的迁移和活性位点的再生，提升了催化剂抗SO2和H2O的性能。课题成果有望为NO催化分解等技术的应用提供理论依据。