Single-atom iron catalyst with single-vacancy graphene-based substrate as a novel catalyst for NO oxidation: a theoretical study

Abstract

Nitric oxide (NO) emitted from coal-fired power plants has raised global concerns.

Comparative Study of NO and CO Oxidation Reactions on Single‐Atom Catalysts Anchored Graphene‐like Monolayer

“…The coadsorptions of gas molecules have larger E ads than that of isolated ones, thus these reactive species (CO−O 2 , NO−O 2 , 2NO and 2CO) on graphenylene‐Pt sheet as the IS configuration would be considered for NO and CO oxidations. For the LH mechanism, the interaction between O 2 and CO (or NO) directly form a peroxo‐type OOCO (or OONO) complex and the dissociation reactions for OOCO (or OONO) to form the product of CO 2 or NO 2 [47–50] . In the mixture of NO and CO flue gas, the coadsorbed 2NO at NM‐SACs are more stable than that of 2CO molecules, thus the preadsorbed NO molecules prefer to occupy the active site and to proceed the CO oxidation via ER mechanism [51] .…”

“…For the LH mechanism reactions, the graphenylene‐Pt (and ‐Pd) sheets exhibit the higher catalytic activities for NO and CO oxidations (<0.4 eV) than those on Mn (0.95 eV and 1.24 eV), Ni (0.73 eV and 0.53 eV) and Ru atoms (0.82 eV and 0.67 eV), [53,54] since the relatively weak coadsorption of gas reactants on Pt and Pd catalysts (<0.3 eV) as starting step are easier to proceed. Meanwhile, these CO oxidation reactions on graphenylene‐Pt (and ‐Pd) sheets also have smaller energy barriers than the single‐atom doped graphene substrates, such as Cu (0.54 eV), [55] Pt (0.46 eV), [56] Pd (0.60 eV), [57] Fe (0.64 eV) [47] . These results illustrate that different reactive substrates play an important role in turning the adsorption stability and activity of metal catalysts, resulting in affect the catalytic reaction mechanisms and energy barriers [58] .…”

Formation Mechanism, Geometric Stability and Catalytic Activity of a Single Iron Atom Supported on N‐Doped Graphene

“…According to the component of flue gases, the volume fraction of CO (500 ppm) is larger than that of the NO molecule (200 ppm) . In detail, the consumption of CO may act as another stage, the NO exhibits higher activity than that of CO molecule and tends to anchor the active site under the CO environments.…”

“…Because the volume fraction of O 2 (4 %) is far greater than that of NO (200 ppm) in coal-fired power plant flue gas. [123] Compared with the isolated NO, CO and O 2 molecule, the coadsorption of CO/ O 2 and NO/O 2 have the relatively larger adsorption energies (> 2.0 eV), so the LH mechanism will be considered for CO and NO oxidation reactions. In addition, the coadsorption of 2CO molecules has the smaller E ads than those of CO/O 2 , indicating that the CO oxidation reaction through the TER mechanism may hardly occur.…”

Adsorption behavior of Pt embedded on N‐doped graphene sheets toward NO and NH3 molecules

“…Among these technologies, SCR technology is the best developed technique for efficiently eliminating NO x emissions due to its efficiency and selectivity. Especially, selective catalytic reduction with ammonia injection (NH 3 ‐SCR) is considered as the most crucial and promising method for reducing NO x emission in coal‐fired power plant . Plenty researchers have shown great interests in the SCR method which utilizes NH 3 as reductants.…”