Abstract:

Selective catalytic reduction of nitrogen oxides by hydrocarbons (SCR-HC) is a promising denitrification method. The efficient redox ability of the catalyst is a key factor to influence its activity. A novel metallic organic framework, MIL-100(Fe), was prepared by hydrothermal method, and mCu-MIL-100(Fe) catalysts with different copper contents were synthesized by ultrasonic impregnation, and the performance of the SCR of NO with C₃H₆ was experimentally investigated in a fixed-bed microreactor. The results showed that the catalytic activity of MIL-100(Fe) was improved by the introduction of Cu. The NO conversion rate of 2.3Cu-MIL-100(Fe) was 100% at 275℃ and maintained above 85% with the N₂ selectivity higher than 90% in the range of 275—400℃. It also has good ability to resist SO₂. The microstructure and physicochemical properties of the catalysts were characterized by various techniques, and the reaction mechanism was further discussed. The N₂ adsorption-desorption results showed that the addition of an appropriate amount of Cu increased the specific surface area of the catalyst and enhanced the adsorption of the reaction gases on the catalyst surface. XPS results proved that the addition of Cu increased the number of oxygen vacancies on the catalyst surface. There was a synergistic effect and electron transfer between Cu and Fe. The H₂-TPR curve indicated that Cu shifted the reduction characteristic peak of the catalyst towards low temperature, enhancing the catalyst's reduction ability.

Key words: nitrogen oxides, selective catalytic reduction (SCR), hydrocarbons, catalyst, Cu modification, SO₂ resistance

摘要：

烃类化合物选择性催化还原氮氧化物（SCR-HC）是一种很有发展前景的脱硝技术。催化剂有效的氧化-还原能力是影响其活性的关键因素。利用水热法制备了新型有机金属骨架MIL-100(Fe)，通过超声浸渍法合成不同Cu含量的mCu-MIL-100(Fe)催化剂，在固定床微反应器中对其催化C₃H₆选择性还原NO的特性进行了实验研究。结果表明Cu的引入使MIL-100(Fe)催化活性得到改善。2.3Cu-MIL-100(Fe)的NO转化率在275℃下可达到100%，275~400℃范围内可维持85%以上NO转化率及90%以上N₂选择性，且具有较好抗SO₂的能力。通过各种技术手段对催化剂的微观结构及物化性质进行了表征，并对反应机理作了进一步讨论。N₂吸附-脱附结果表明，加入适量Cu可以增大催化剂的比表面积，并增强催化剂表面对反应气体的吸附能力；XPS研究结果表明，Cu可以提高催化剂表面的氧空位数目。Cu与Fe之间具有协同作用，二者之间存在电子转移现象。H₂-TPR曲线表明Cu使催化剂的还原特征峰向低温方向移动，增强了其还原性能。

关键词: 氮氧化物, 选择催化还原, 碳氢化合物, 催化剂, Cu改性, 抗SO₂性能