Mn-Doped CaO Catalytic-Adsorption Synergistic Mechanism for Denitration and Carbon Reduction Based on DFT

doi:10.12068/j.issn.1005-3026.2025.20240053

Abstract

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

CLC Number:

O 643.31

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.

Figures/Tables 13

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

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

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

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

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

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

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

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)

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

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

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

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

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

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