潜在的风险显著的N2O排放没有改变NO转换商业V2O5/TiO2催化剂在工作条件下
Jiaying Xing1, Qitong Xue1,2, Jianjun Chen1
1State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China.
Environmental science & technology
|December 14, 2023
概括
瓦纳催化剂上的沉积可以在选择性催化降解 (SCR) 氧化 (NOx) 过程中增加氧化 (N2O) 排放. 这是通过非选择性催化还原 (NSCR) 发生的,由于催化剂的氧化还原特性发生了变化,突出显示需要监测N2O.
科学领域:
- 环境化学环境化学
- 催化科学 催化科学
- 材料科学 材料科学 材料科学
背景情况:
- 基于的催化剂对于通过选择性催化减排 (SCR) 控制工业NOx排放至关重要.
- 在复杂的条件下,SCR产生的潜在N2O温室气体排放未得到充分研究.
- 在V2O5/TiO2催化剂上的沉积被研究其对N2O形成的影响.
研究的目的:
- 调查沉积对V2O5/TiO2催化剂在N2O排放方面的影响.
- 用改性催化剂阐明NH3-SCR过程中N2O形成的机制.
- 评估对工业排放控制战略的影响.
主要方法:
- 实验研究NH3-SCR使用商业V2O5/TiO2催化剂,具有不同的负载.
- 在不同温度下对NOx和N2O度进行气相分析.
- 密度函数理论加U (DFT+U) 计算,以了解表面相互作用和反应机制.
主要成果:
- 沉积 (2重 %) 显著增加了N2O排放,从27.8到199.2 ppm在350°C.
- N2O/(N2O+N2) 的比率在修改后从2.5%增加到19.4%.
- 非选择性催化还原 (NSCR) 被确定为N2O形成的主要途径在250400°C.
- 在Cr和V物种之间的共价相互作用促进表面V5+,有利于NSCR而不是标准SCR.
结论:
- 改性V2O5/TiO2催化剂可以导致大量的N2O排放,而不会显著改变NOx去除效率.
- 由Cr-V相互作用和表面V5+增加所驱动的增强NSCR通路,负责N2O形成.
- 监测N2O排放与NOx监测一起,对于工业SCR过程中有效的温室气体减排至关重要.
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