Daengngern, Rathawat

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Preferred name
Daengngern, Rathawat
Alternative Name
Daengngern, R.
Main Affiliation
Email
rathawat.da@kmitl.ac.th

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    Item type:Publication,
    Bridging the Gap in Understanding the Mechanism of NH3 Formation During NO Reduction by CO in the Presence of H2O Over Rh/Al2O3 Catalysts: DFT Study
    (2026-02-01)
    Wangphon, Chanthip
    ;
    Khajondetchairit, Patcharaporn
    ;
    Rittiruam, Meena
    ;
    Ektarawong, Annop
    ;
    Alling, Björn
    Ammonia (NH<inf>3</inf>) formation from nitric oxide (NO) and carbon monoxide (CO) in the presence of water is a promising pathway for low-temperature NO<inf>x</inf> reduction. In this work, density functional theory (DFT) calculations were used to investigate the mechanism of NH<inf>3</inf> formation on a Rh(111)/γ-Al<inf>2</inf>O<inf>3</inf>(110), in which the Rh(111) and γ-Al<inf>2</inf>O<inf>3</inf>(110) were considered separately. NO readily dissociates on the Rh site, forming N*, which reacts with CO to produce the key intermediate of NCO*. Meanwhile, water dissociates more easily on γ-Al<inf>2</inf>O<inf>3</inf>(110), providing H* species. The hydrolysis of NCO* can proceed via two pathways: on Rh(111), it forms HNCO, while on γ-Al<inf>2</inf>O<inf>3</inf>(110), it forms HNCOH*. Both intermediates subsequently decompose into NH* species, which are then hydrogenated to produce NH<inf>3</inf>. The Rh pathway is more favorable in both kinetics and thermodynamics, while the support mainly supplies hydrogen through water activation. These results suggest a dual-site mechanism in which Rh drives the main transformation, and γ-Al<inf>2</inf>O<inf>3</inf>(110) assists via hydrogen transfer. This work presents the individual roles of Rh and Al<inf>2</inf>O<inf>3</inf> surfaces in NO reduction with CO, producing NH<inf>3</inf>, which is relevant to catalytic behavior under humid conditions.