Structure–activity relationships of Pt/Al2O3 catalysts for CO and NO oxidation at diesel exhaust conditions

Boubnov, Alexey; Dahl, Søren; Johnson, Erik; Molina, Anna Puig; Simonsen, Søren Bredmose; Cano, Fernando Morales; Helveg, Stig; Lemus-Yegres, L.J.; Grunwaldt, Jan‐Dierk

doi:10.1016/j.apcatb.2012.07.029

Cited by 152 publications

(143 citation statements)

References 48 publications

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“…As temperature was increased the concentration of CO and HC was reduced (once the light-off is reached) and the NO 2 concentration was increased. This suggests the relevant role of the presence of CO and HC to determine the NO 2 concentration after the catalyst which has also been previously extensively studied [19]- [23].…”

Section: Resultsmentioning

confidence: 98%

Enhancing the low temperature oxidation performance over a Pt and a Pt–Pd diesel oxidation catalyst

Herreros

Gill

Lefort

et al. 2014

Applied Catalysis B: Environmental

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The influence of hydrogen over platinum and combined platinum-palladium diesel oxidation catalysts were investigated on the oxidation kinetics of CO, HC and NO. Although H 2 has been reported to have a positive effect on CO and HC oxidation as well as NO 2 formation over platinum catalysts, there is still uncertainty whether this is due to the temperature rise caused by H 2 oxidation or the result of a change in the reaction kinetics of CO, HC and NO oxidation by the production of intermediate species. The results have showed smaller H 2 concentrations are more effective in improving the catalyst light-off temperature as well as promoting NO oxidation over both platinum and platinum-palladium catalysts. It is suggested that these benefits are a result of not only the exothermic reactions which in turn increase the local catalyst temperature but also H 2 increasing the rate of reactions and the species accessibility to the catalyst active sites thus further CO, HC and NO oxidation can occur at lower catalyst temperatures.

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Section: Resultsmentioning

confidence: 98%

Enhancing the low temperature oxidation performance over a Pt and a Pt–Pd diesel oxidation catalyst

Herreros

Gill

Lefort

et al. 2014

Applied Catalysis B: Environmental

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“…However, the TOF does not follow this 324 trend. For CO oxidation, the maximum in TOF occurs for 2-3 nm Pt particles [12], while the TOF increases with 325…”

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confidence: 99%

“…Pt particle size for both HC oxidation [13][14][15][16][17][18] and NO oxidation [12,19,20]. The observation that the optimum 326 particle diameter coincides with a maximum in TOF for CO oxidation but not for HC and NO oxidation indicates 327 that the reasons for the maxima in rates of reaction are different.…”

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confidence: 99%

The Effect of Pt Particle Size on the Oxidation of CO, C3H6, and NO Over Pt/Al2O3 for Diesel Exhaust Aftertreatment

et al. 2017

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8Platinum-based oxidation catalysts applied for diesel exhaust aftertreatment constitute a significant part of 9 system costs. Effective utilization of platinum is therefore relevant to reduce costs while retaining 10 performance. To this end, the influence of Pt particle size on catalytic activity for CO, hydrocarbon, and NO 11 oxidation was studied. 1 wt.% Pt/Al2O3 catalysts were prepared by wet impregnation, drying, and different 12 calcination and thermal treatments, yielding Pt particles with diameters between 1.3 and 18.7 nm, as 13 determined by CO pulse titration and transmission electron microscopy. Activity measurements for CO, C3H6, 14 and NO oxidation showed an optimal Pt particle size with respect to the mass based activity between 2-4 nm 15 for all three reactions. From measured turnover frequencies and site statistics of Pt particles, the reactions 16 appear to be mainly catalyzed by terrace atoms, which are most abundant between 2-4 nm. The decrease in 17 catalytic activity for large Pt particles is therefore due to the diminishing Pt surface area, while the decrease in 18 activity for small particles is due to the lack of terrace atoms required for CO, HC, and NO oxidation.

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“…The NOox reaction must occur together with COox and the oxidation of hydrocarbons to H 2 O and CO 2 and of sulfur-containing species to SO 2 e.g. in the treatment of Diesel exhaust gases (thus, under oxygen-rich conditions) and is highly desirable, as it enhances the efficiency of the successive steps of the treatment, among which are soot oxidation, 13 the selective catalytic reduction of NO 2 to N 2 with NH 3 (or urea), 14,15 etc. A strong oxidation catalyst, the Diesel Oxidation Catalyst (DOC), 15 is placed upstream of the other catalysts to promote the COox, NOox, hydrocarbon and sulfur oxidation reactions.…”

Section: Introductionmentioning

confidence: 99%

Ligand/cluster/support catalytic complexes in heterogeneous ultrananocatalysis: NO oxidation on Ag₃/MgO(100)

Sementa

Barcaro

Negreiros

et al. 2014

Phys. Chem. Chem. Phys.

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In the present work we explore via first-principles simulations whether the ligand/cluster/support catalytic complex generated by CO oxidation over silver trimers deposited on the regular MgO (100) surface -i.e. a Ag 3 /carbonate or Ag 3 (CO 3 )/MgO(100) species -can be used as a catalyst in a different reaction: the selective oxidation of NO to NO 2 (or NOox). The Ag 3 (CO 3 )/MgO(100) complex is first shown to be reasonably stable at room temperature in terms of both disaggregation and sintering, and that it can be generated from Ag 3 adsorbed onto an oxygen vacancy defect of the regular MgO (100) surface under oxidation conditions. It is then found that the Ag 3 (CO 3 )/MgO(100) species transforms under NOox conditions into an even more complex aggregate, a mixed carbonate/double-nitrite Ag 3 (CO 3 )(NO 2 ) 2 /MgO(100) species, which can then act as an efficient catalyst of NOox. It is noteworthy that under NOox reaction conditions a different ligand/cluster/support catalytic complex is formed with respect to the original COox one. These findings prove the diversity of the catalytic chemistry of subnanometer (or ultranano) metal clusters deposited on oxide substrates, associated with the formation of many different ligand/cluster/support aggregates, the vast amount of combinatorial possibilities thus opening, and the need for computational approaches to perform systematic structural and stoichiometric searches in order to cope with such a multiform diversity.

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Structure–activity relationships of Pt/Al2O3 catalysts for CO and NO oxidation at diesel exhaust conditions

Cited by 152 publications

References 48 publications

Enhancing the low temperature oxidation performance over a Pt and a Pt–Pd diesel oxidation catalyst

Enhancing the low temperature oxidation performance over a Pt and a Pt–Pd diesel oxidation catalyst

The Effect of Pt Particle Size on the Oxidation of CO, C3H6, and NO Over Pt/Al2O3 for Diesel Exhaust Aftertreatment

Ligand/cluster/support catalytic complexes in heterogeneous ultrananocatalysis: NO oxidation on Ag₃/MgO(100)

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Structure–activity relationships of Pt/Al2O3 catalysts for CO and NO oxidation at diesel exhaust conditions

Cited by 152 publications

References 48 publications

Enhancing the low temperature oxidation performance over a Pt and a Pt–Pd diesel oxidation catalyst

Enhancing the low temperature oxidation performance over a Pt and a Pt–Pd diesel oxidation catalyst

The Effect of Pt Particle Size on the Oxidation of CO, C3H6, and NO Over Pt/Al2O3 for Diesel Exhaust Aftertreatment

Ligand/cluster/support catalytic complexes in heterogeneous ultrananocatalysis: NO oxidation on Ag3/MgO(100)

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Ligand/cluster/support catalytic complexes in heterogeneous ultrananocatalysis: NO oxidation on Ag₃/MgO(100)