高硫中低温下选择性还原NOx催化体系及原位机理研究

The characterizations of glass & ceramic kilns flue gas are high concentrations of dusts, nitrogen oxides, and sulfur dioxide and middle-low temperature of flue gas (about 180~300℃). With these conditions, the denitration efficiency of traditional selective catalytic reduction (SCR) catalyst is low. There is no any mature and available technology lead to high concentration of nitrogen oxides direct emissions from glass & ceramic kilns. In order to adapt to the increasingly stringent environmental regulations and reduce hazards of NOx to the environment and human health, research and development of new SCR catalyst will be the new tasks and goals of environmental catalysis field. The new catalyst can efficiently remove NOx at middle-low temperature (180~300℃) and high concentration of SO2 environment. The activity of traditional commercial SCR catalyst is poor at low temperature and the sulfur-tolerance & water-resistance of low-temperature SCR catalyst is weak, in accordance with these problems, this project will combinatorially construct highly efficient catalyst system which taking into account the activity of selective catalytic reduction of NOx at middle-low temperature and sulfur-tolerance & water-resistance. At the same time, we plan to explore the structure-activity relationship between the intrinsic properties of the catalyst and catalytic activity, and discover the process of catalytic NOx reduction at middle-low temperature and inhibition mechanism of SO2, H2O. Acquisition of new knowledge will provide guidance and reference to the applications of SCR DeNOx technology in the field of glass & ceramic kilns and the research of related catalyst system.

玻璃/陶瓷窑炉烟气灰飞含量高、氮氧化物（NOx）和SO2浓度高、烟温偏低（180~300℃），传统选择性催化还原（SCR）催化剂（起活温度350℃）在该工况下脱硝效率低，无成熟可用技术导致高浓度的氮氧化物直接排放。为了适应日益严格的环保法规，减轻NOx对环境和人类健康的危害，研究开发新型SCR催化剂并实现其在中低温（180~300℃）、高硫环境下高效脱除NOx，将成为环境催化领域新的任务与目标。本项目针对传统商用SCR催化剂低温活性差、低温SCR催化剂耐硫抗水能力弱等问题，组合构建兼顾中低温选择性催化NOx还原活性与耐硫抗水性的高效催化剂体系；探索催化剂本征性能与催化活性之间的构效关系；获得中低温环境下催化NOx还原过程及SO2、H2O抑制作用机理。获取的新知识为SCR脱硝技术在玻璃/陶瓷窑炉领域的应用及相关催化剂体系的研究提供借鉴和指导。

玻璃/陶瓷窑炉烟气灰飞含量高、氮氧化物（NOx）和SO2 浓度高、烟温偏低（180~300℃），传统选择性催化还原（SCR）催化剂（起活温度350℃）在该工况下脱硝效率低，无成熟可用技术导致高浓度的氮氧化物直接排放。为了适应日益严格的环保法规，减轻NOx 对环境和人类健康的危害，研究开发新型SCR 催化剂并实现其在中低温（180~300℃）、高硫环境下高效脱除NOx，将成为环境催化领域新的任务与目标。本项目针对传统商用SCR 催化剂低温活性差、低温SCR 催化剂耐硫抗水能力弱等问题，利用组合化学的原理采用固相法制备了36种过渡金属氧化物或者复合金属氧化物，并对其中低温选择性催化还原NOx的活性及其耐硫性进行了评价，经过筛选得到兼具较佳的中低温SCR活性以及耐硫性能的Cr-CeOx复合金属氧化物催化剂。利用BET、XRD、NH3-TPD、H2-TPR、XPS和in situ DRIFTS等表征手段对催化剂进行表征，结果表明在Cr-CeOx双金属氧化物表面，未结晶的铬有助于催化剂的活性，能更有效的去除NOx；在对反应机理的进行研究时，发现催化剂表面同时存在Lewis以及Brønsted酸性位，吸附的NH3(ad)与NH4+均能参与反应，反应遵循Eley-Rideal机理。同时，对SO2对催化反应的影响以及催化剂的耐硫性能进行了探索，发现SO2在NH3-SCR反应中会与NH3反应生成(NH4)2SO4并在催化剂表面沉积；同时也会破坏Cr-CeOx催化剂表面的Lewis酸性位，这些都是导致催化剂的活性下降的重要原因；而铈的存在则有助于催化剂的抗硫性提升。获取的新知识为SCR 脱硝技术在玻璃/陶瓷窑炉领域的应用及相关催化剂体系的研究提供借鉴和指导。