Adsorption states of typical intermediates on Ag/Al2O3 catalyst employed in the selective catalytic reduction of NOx by ethanol

Abstract

The adsorption of ethanol and important intermediates onto Ag/Al2O3 catalyst employed in the selective catalytic reduction of NOx by ethanol was simulated by density functional theory. Considering the interaction between Ag metal and Al2O3 support, typical Ag-O-Al entities, i.e., Ag-O-Altetra and Ag-O-Alocta, (tetra = tetrahedral and octa = octahedral refer to the coordination sites of Al), were selected as potential adsorption sites on the surface of the catalyst. Ethanol, and enolic and isocyanate species were preferentially adsorbed and activated by Ag-O-Altetra entities rather than by Ag-O-Alocta entities. The strong Lewis acidity of Altetra in the Ag-O-Altetra entity was very important, enabling the entity to accept an electron via forward donation from either the C-O σ bond in ethanol or the N-C σ bond in the −NCO species. Moreover, the hybridization of the Ag and Al orbitals was critical for electron back donation from the Ag-O-Altetra entity to the C-C π bond in the enolic species or N-C π bond in the −NCO species. The significant activation of the N-C bond in −NCO on the Ag-O-Altetra sites facilitated cleavage of −NCO to form N2. Thus, we can conclude that the acidity of the Al site and the interaction between Ag and Al play key roles in the selective catalytic reduction of NOx by ethanol over Ag/Al2O3.

Resolving the puzzle of single-atom silver dispersion on nanosized γ-Al2O3 surface for high catalytic performance

“…DFT calculations were carried out with a plane-wave energy cutoff of 400 eV. Based on our previous reports 68,69 , the dehydrated (110) and (100) surfaces of γ-Al 2 O 3 were modeled using (2 × 2) supercells. According to our preliminary convergence test, Monkhorst−Pack k-point sets of (1 × 1 × 1) were used for the Al 2 O 3 surfaces.…”

Synthesis of Silver Nanoparticles Loaded onto Polymer-Inorganic Composite Materials and Their Regulated Catalytic Activity

“…The introduction of silver nanoparticles (AgNPs) has attracted significant scientific interest due to their unique optical and electronic properties [1,2,3], remarkable catalytic activities and selectivities [4,5], and significant antibacterial activities [6,7]. AgNPs are widely used in catalysis [8,9,10], surface-enhanced Raman scattering (SERS) [11], biomedicine [12,13], and environmental treatment [14,15,16,17].…”