对H2O对V2O5/TiO2催化剂对NO的选择性催化还原的影响的理论见解
Boyu Wu1, Shengen Zhang1, Mingtian Huang1
1Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China. zhangshengen@mater.ustb.edu.cn.
烟气中的水使选择性催化还原 (SCR) 的V2O5/TiO2催化剂失活. 本研究使用DFT揭示了水吸附如何影响催化剂酸度,并阻碍对SCR效率至关重要的氨吸附.
科学领域:
- 催化剂是一种催化剂.
- 表面科学是一门学科.
- 计算化学的计算化学
背景情况:
- 在二氧化 (V2O5/TiO2) 催化剂上的氧化对于选择性催化降解 (SCR) 的NOx与氨至关重要.
- 烟气中的水是这些催化剂在低温下失活的已知原因.
- 了解水的影响理论机制对于开发耐水性SCR催化剂至关重要.
研究的目的:
- 为了阐明水 (H2O) 在V2O5/TiO2催化剂表面上的吸附过程.
- 用密度函数理论 (DFT) 澄清由H2O诱导的失活机制.
- 为优化在水存在下催化剂性能提供见解.
主要方法:
- 密度函数理论 (DFT) 的计算被用来建模V2O5/TiO2催化剂表面.
- 研究了H2O在模拟的催化剂表面上的吸附过程.
- 进行了初始热力学计算,以评估吸附稳定性和对氨 (NH3) 吸附的影响.
主要成果:
- 水与暴露的原子强烈相互作用,改变了氧化瓦纳 (VOx) 位点的电子结构.
- 吸附将易斯酸部位转化为布伦斯特酸部位,从而降低易斯酸度.
- H2O吸附在覆盖率低时稳定,但在覆盖率高时不太有利,阻碍了对SCR至关重要的NH3吸附.
结论:
- 水吸附显著影响V2O5/TiO2催化剂的表面化学和酸度.
- 低H2O覆盖率 (<15%) 可能会增强NH3吸附,而高覆盖率会阻碍它.
- 这项研究提供了对H2O效应的电子尺度理解,指导开发更耐水性SCR催化剂.
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