期刊
CHEMICAL ENGINEERING JOURNAL
卷 361, 期 -, 页码 578-587出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2018.12.103
关键词
NH3-SCR; NO; CuMn2O4 catalyst; Reaction pathway; Density functional theory
资金
- National Key R&D Program of China [2018YFC1901303]
- National Natural Science Foundation of China [51661145010]
- Enterprise Technological Innovation Project of Wuhan [2018060402011256]
- National Postdoctoral Program for Innovative Talents [BX20180108]
The relationship between the types of active sites and the selective catalytic reduction (SCR) activity of NO with NH3 over CuMn2O4 spinel was established through density functional theory (DFT) calculations. A skeletal reaction scheme including the possible elementary steps was proposed to understand N-2, NO2 and N2O formation during NH3-SCR of NO over CuMn2O4 catalyst. DFT calculation results show that chemisorption mechanism is responsible for the adsorption of reactants, possible intermediates and products over CuMn2O4(100) surface. 2-fold coordinated surface Cu atom plays a crucial role in NH3-SCR of NO, because it is the active site for NH3 and NO adsorption. NH2 produced from NH3 dehydrogenation is identified as a key reactive intermediate of SCR reaction. NH2 easily reacts with the adsorbed NO to form N-2 and H2O via NH2*+ NO* -> N-2*+ H2O* which is activated by 6.87 kJ/mol. The activation energy barrier of N2O formation over CuMn2O4 catalyst is much higher than that of N-2 formation, which indicates that CuMn2O4 catalyst shows a good N-2 selectivity for NO reduction. The optimal reaction pathway for NH3-SCR of NO over CuMn2O4(100) surface is a two-step process controlled by NH2*+* -> NH2*+ H* and NH2*+ NO* -> N-2*+ H2O*. The rate-determining step of N-2 formation during NO reduction is the first dehydrogenation reaction of NH3.
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