基于DFT的Mn掺杂CaO催化-吸附协同脱硝降碳机理

doi:10.12068/j.issn.1005-3026.2025.20240053

摘要/Abstract

摘要：

基于密度泛函理论(DFT)构建了以CaO为催化基底、金属Mn为掺杂金属的催化-吸附双功能催化剂，探究了NO，CO与降碳反应物CO₂在催化剂表面的吸附行为及其脱硝降碳反应机理.结果表明：CO和NO分别以弱化学吸附和化学吸附的形式吸附在CaO表面；Mn掺杂显著增强CaO催化剂对CO和NO的吸附性能；Mn掺杂前后的CaO催化剂均表现出较好的CO₂吸附性能；在CaO和Mn-CaO表面，CO-SCR反应速率的决定步骤为NO的解离反应，Mn掺杂使该反应的能垒降低了约0.27 eV；随着温度升高，Mn-CaO催化剂的决速步反应自由能能垒逐渐升高，而CO₂吸附反应的自由能变化（绝对值）则逐渐降低，表明其具有良好的低温脱硝降碳性能.本研究为协同脱硝降碳双功能催化剂的设计与研发提供了新思路.

关键词: 脱硝降碳, 催化-吸附, CO-SCR, Mn改性, 第一性原理

Abstract:

A dual-functional catalyst with CaO as the substrate and Mn as the dopant metal was constructed using density functional theory （DFT）. The adsorption behaviors of NO， CO and carbon reduction reactant （CO₂） were studied， alongside the reaction mechanisms for denitration and carbon reduction. Results show that CO and NO adsorb on the CaO surface through weak and strong chemical adsorption， respectively， with Mn doping enhancing adsorption for both. The Mn-doped CaO catalysts also exhibit excellent CO₂ adsorption properties， making them effective decarbonization carriers. The rate-determining step for the CO-SCR reaction is the dissociation of NO， with Mn doping lowering its energy barrier by approximately 0.27 eV. As temperature increases， the free energy barrier of the rate-determining step reaction over the Mn-CaO catalyst gradually rises， while the absolute value of the free energy change for the CO₂ adsorption reaction gradually decreases， demonstrating the catalyst's superior low temperature denitration and decarbonization performance. This study offers new insights for developing dual-functional catalysts for simultaneous denitration and carbon reduction.

Key words: denitration and decarbonization, catalytic-adsorption, CO-SCR, Mn-modified, first principle

中图分类号:

O 643.31

郭锐, 谢华清, 于震宇, 邵正日. 基于DFT的Mn掺杂CaO催化-吸附协同脱硝降碳机理[J]. 东北大学学报（自然科学版）, 2025, 46(10): 66-73.

Rui GUO, Hua-qing XIE, Zhen-yu YU, Zheng-ri SHAO. Mn-Doped CaO Catalytic-Adsorption Synergistic Mechanism for Denitration and Carbon Reduction Based on DFT[J]. Journal of Northeastern University(Natural Science), 2025, 46(10): 66-73.

图/表 13

图1 优化后的CaO表面和Mn-CaO表面模型(代表Ca，代表O，代表Mn)

Fig.1 Optimized models of CaO and Mn-CaO surfaces( represents Ca; represents O; represents Mn)

图2 CO在CaO表面的吸附构型(代表Ca，代表O，代表C)

Fig.2 Adsorption configuration of CO on CaO surface ( represents Ca; represents O; represents C)

图3 CO在Mn-CaO表面的吸附构型( 代表Ca，代表O，代表C )

Fig.3 Adsorption configuration of CO on Mn-CaO surface ( represents Ca; represents O; represents C)

图4 CO在CaO和Mn-CaO表面最稳定吸附构型的PDOS图

Fig.4 PDOS diagram of the most stable adsorption configuration of CO on CaO and Mn-CaO surfaces

图5 NO在CaO表面的吸附构型( 代表Ca，代表O，代表N )

Fig.5 Adsorption configuration of NO on CaO surface ( represents Ca, represents O, represents N)

图6 NO在Mn-CaO表面的吸附构型( 代表Ca，代表O，代表N )

Fig.6 Adsorption configuration of NO on Mn-CaO surface ( represents Ca, represents O, represents N)

图7 NO在CaO和Mn-CaO表面最稳定吸附构型的PDOS图

Fig.7 PDOS diagram of the most stable adsorption configuration of NO on CaO and Mn-CaO surfaces

图8 CaO和Mn-CaO表面CO-SCR反应能阶图( 代表Ca，代表O，代表Mn，代表C，代表N)

Fig.8 Energy level diagram of CO-SCR reaction on CaO and Mn-CaO surfaces ( represents Ca; represents O; represents Mn; represents C; represents N)

表1 CaO和Mn-CaO表面CO-SCR反应能垒及反应能

Table 1 Energy barrier and reaction energy of CO-SCR reaction on CaO and Mn-CaO surfaces

反应		CaO		Mn-CaO
反应		E_a/eV	E_r/eV	E_a/eV	E_r/eV
CO(g)+NO(g)→CO+NO	IS1→IM1		-1.201		-1.483
CO+NO→CO+N+O*	IM1→IM2	3.955	2.781	3.689	2.126
CO+N+O→CO₂+N*	IM2→IM3	0.967	-3.716	0.245	-4.093
CO₂+N→CO₂(g)+N*	IM3→FS1		0.965		1.331
N+N→N₂*	IS2→IM4	3.240	-6.474	0.518	-5.576
N₂*→N₂(g)	IM4→FS2		0.165		2.787

图9 CO2在CaO表面的吸附构型( 代表Ca，代表O，代表C )

Fig.9 Adsorption configuration of CO2 on CaO surface ( represents Ca; represents O; represents C)

图10 CO2在Mn-CaO表面的吸附构型( 代表Ca，代表O，代表C，代表Mn )

Fig.10 Adsorption configuration of CO2 on Mn-CaO surface ( represents Ca; represents O; represents C; represents Mn)

图11 CO2在CaO和Mn-CaO表面最稳定吸附构型的PDOS图（a）—CaO表面；（b）—Mn-CaO表面.

Fig.11 PDOS diagram of the most stable adsorption configuration of CO2 on CaO and Mn-CaO surfaces

图12 自由能能垒和吸附自由能能变随温度的变化

Fig.12 Variation of free energy barrier and adsorption free energy change with temperature

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