Catalytic reduction of NO in the presence of benzene on a Pt(332) surface

A DFT study of the NO dissociation on gold surfaces doped with transition metals

“…Also important for supporting the choice of the Au(110) surface are the previous reports on the structural sensitivity of the reaction of NO x reduction on metallic catalysts. 21,50,[60][61][62][63][64][65][66] The (111) and (110) slab models used in this work consist of 2 × 2 unit cells with respect to the minimal unit cell and have a thickness of four metallic layers. 73 The convergence of the results with the number of atomic layers in the slab was checked in previous works.…”

“…Therefore, the cleavage of the N-O bond seems to be the crucial step during the reaction of NO reduction. 13,21,[49][50][51] Vinod et al 52 considered the Au(310) surface model catalyst for investigating NO reduction on gold, concluding that the reaction mechanism based on bond dissociation of NO species is more plausible, which is surprising taking into account the high activation energy barrier (E act = ∼3.9 eV) associated to the reaction of NO dissociation on the Au(111) surface. 48 This is a very large value, especially, when compared with the NO dissociation energy barriers on surfaces of more reactive metals such as Ir(100), 53 Rh(111), 54 Rh(100), 55,56 or Rh(211), 54 surfaces, with E act = ∼0.5 eV, ∼1.4 eV, ∼0.4 eV, and ∼0.7 eV, respectively.…”

“…57 Our findings are in agreement with previous experimental studies where it was found that the NO reduction on gold based catalysts at moderate temperatures started only if hydrogen species were available. 51,58,59 All of these suggestions must be handled with caution since the reaction of NO dissociation, as other steps in the reaction of NO reduction, was found to be structure sensitive, 21,50,[60][61][62][63][64][65][66][67] i.e., is influenced by intrinsic specificities of the catalyst surfaces considered (e.g., special sites close to undercoordinated atoms).…”

“…This information is very important to understand the NO x reduction on gold based catalysts. Thus, the NO dissociation, a key step in the NO x reduction by noble metal based catalysts, 13,21,[49][50][51] is studied here on a series of doped Au(111) and Au(110) surfaces. The latter surface presents undercoordinated atoms and, upon comparison with the results for the flat Au(111) surface, will allow the understanding of the structure sensitivity of the NO dissociation reaction.…”

“…2 In the case of motor vehicles the elimination of these species is usually carried out through its reduction to N 2 using the conventional three-way catalysts which presents Pt, Pd, and Rh in its active phase, [3][4][5] being here a central reaction the NO reduction with CO (NO + CO → 1 2 N 2 + CO 2 ) since these gases are among the main contaminants emitted by the motor vehicles. Furthermore, other catalysts based on noble metals dispersed on a support were also tested for the NO x elimination 6,7 as those based on Ru, 8 Rh, 9 Ir, [10][11][12] Pd, [13][14][15] Pt, [16][17][18][19][20][21][22] Au, [23][24][25][26] Ag, [27][28][29][30] and also on alloys of these metals with cheaper metals. 8,9,20,22,31,32 In some cases the noble metal was successfully replaced by other elements.…”