Geng Xuan, Xie Chaoyue, Zhu Baozhong, Chen Jiuyu, Sun Yunlan, Xu Minggao
School of Petroleum and Natural Gas Engineering, Changzhou University, Changzhou, Jiangsu, 213164, People's Republic of China.
Center for Advanced Combustion and Energy, University of Science and Technology of China, Hefei, Anhui, 230026, People's Republic of China.
Environ Sci Pollut Res Int. 2022 Dec;29(58):88256-88268. doi: 10.1007/s11356-022-21912-5. Epub 2022 Jul 13.
γ-FeO has an excellent low-temperature selective catalytic reduction (SCR) deNO performance, but its resistance to alkaline earth metal calcium (Ca) is poor. In particular, the detailed mechanism of Ca poisoning on the γ-FeO catalyst at the atomic level is not clear. Hence, the density functional theory method was used in this research to investigate the influence mechanism of Ca poisoning on the NH-SCR over the γ-FeO catalyst surface. The findings reveal that NH, NO, and O molecules can bind to the γ-FeO (001) surface to generate coordinated ammonia, monodentate nitroso, and adsorption oxygen species, respectively. The main active site is Fe-top. For the γ-FeO with Ca poisoning, the Ca atom has a high adsorption energy on the surface of γ-FeO (001), which covers the catalyst surface and reduces the active sites. The presence of Ca atom decreases the adsorption performance of NH, while slightly improving the NO and O adsorption. In particular, the Ca atom restrains the NH activation and NH formation, which is detrimental to the NH-SCR process.
γ-FeO具有优异的低温选择性催化还原（SCR）脱硝性能，但其对碱土金属钙（Ca）的抗性较差。特别是，Ca对γ-FeO催化剂中毒的详细原子水平机制尚不清楚。因此，本研究采用密度泛函理论方法来研究Ca中毒对γ-FeO催化剂表面NH-SCR的影响机制。研究结果表明，NH、NO和O分子可分别与γ-FeO(001)表面结合，生成配位氨、单齿亚硝基和吸附氧物种。主要活性位点是Fe-top。对于Ca中毒的γ-FeO，Ca原子在γ-FeO(001)表面具有较高的吸附能，覆盖了催化剂表面并减少了活性位点。Ca原子的存在降低了NH的吸附性能，同时略微提高了NO和O的吸附。特别是，Ca原子抑制了NH的活化和NH的形成，这对NH-SCR过程不利。
