Mechanistic effects of Water on Carbon monoxide and propylene oxidation on platinum and palladium bimetallic catalysts

Hazlett, Melanie J.; Epling, William S.

doi:10.1016/j.cattod.2020.01.024

Cited by 15 publications

(9 citation statements)

References 27 publications

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“…In Figure 4 c we show that the addition of 2 % water to the feed has no detectable effect on CO oxidation over the PdCu stage, if anything a small improvement in CO lightoff was observed which is consistent with previous work on CO oxidation on Pd. [26] While our experimental setup did not allow feeding more water, water usually has a digital effect on oxidation performance, and we expect no significant difference with higher water concentrations. The loss of NO oxidation activity over the downstream PtPd stage is expected and consistent with reports of water inhibition on Pt sites.…”

Section: Resultsmentioning

confidence: 90%

PdCu Alloy Catalyst for Inhibition‐free, Low‐temperature CO Oxidation

Song,

Svadlenak,

Bathena

et al. 2023

ChemCatChem

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Designing robust catalysts for low‐temperature oxidation is pertinent to the development of advanced combustion engines to meet increasingly stringent emissions limitations. Oxidation of CO, hydrocarbon and NO pollutants over platinum‐group catalysts suffer from strong inhibition due to their competitive adsorption, while coinage metals are generally slow at activating O2. Through computational screening we discovered a PdCu alloy catalyst that completely oxidizes CO below 150 °C without inhibition by NO, propylene or water. This is attributed primarily to geometric effects and the presence of CO bound to Pd sites within the Cu‐rich surface of the PdCu alloy. We demonstrate that the novel PdCu catalyst can be used in tandem with a PtPd catalyst to achieve sequential, inhibition‐free, complete oxidation of CO in a two‐bed system, while also achieving 50% NO conversion below 120 °C. Moreover, neither water nor propylene adversely affect the low temperature CO oxidation activity.

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Section: Resultsmentioning

confidence: 90%

PdCu Alloy Catalyst for Inhibition‐free, Low‐temperature CO Oxidation

Song,

Svadlenak,

Bathena

et al. 2023

ChemCatChem

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“…The supported Pd was found to be slightly less reactive than Pt. On the other hand, when Hazlett and Epling tested the oxidation of C 3 H 6 over monometallic and bimetallic Pt and Pd, they found the Pd to have a superiority of higher activity compared to Pt, while the bimetallic Pt/Pd had an intermediate catalytic activity.…”

Section: Resultsmentioning

confidence: 99%

“…The supported Pd was found to be slightly less reactive than Pt. On the other hand, when Hazlett and Epling75 tested the oxidation of C 3 H 6 over monometallic and bimetallic Pt and Pd, they found the Pd to have a superiority of higher activity compared to Pt, while the bimetallic Pt/Pd had an intermediate catalytic activity.Figure6aalso presents X C 2 H 6 on the surface of the Pd wire, with the conversion taking place within the temperature range of 325−460 °C. The temperature range at which the C 2 H 6 oxidized on the Pd wire in our experiment is close to the results reported byYao,…”

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confidence: 99%

Comparative Study of the Catalytic Oxidation of Hydrocarbons on Platinum and Palladium Wires and Nanoparticles

et al. 2022

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This paper presents a comparative experimental study of the oxidation of light alkanes (methane and ethane) and alkenes (ethylene and propylene) catalyzed by unsupported platinum (Pt) and palladium (Pd). The oxidation was studied under a wide range of reaction conditions, such as temperatures, residence times, and mixture equivalence ratios. Two different catalyst morphologies were investigated: a packed bed of nanoparticles and a wire coiled inside a tube reactor. The order of hydrocarbons in terms of their oxidation activity on the Pt and Pd was found to be consistent regardless of the wire/nanoparticle morphology, with propylene exhibiting the highest reactivity followed by ethylene, ethane, and then methane. The effects of residence time on the oxidation of hydrocarbons showed similar trends with the two types of catalysts, whereby a longer residence time leads to a higher oxidation activity. However, the degree of that activity enhancement was insignificant with the nanoparticles. On the other hand, the effects of the equivalence ratio, φ, were significantly different between the two catalyst configurations. In the near-adiabatic wire reactor, the oxidation activity increases with increasing φ due to the heat release and higher temperature ramp along the reactor. The reverse is true in the isothermal bed of nanoparticles. Analysis of the surface of the catalyst using X-ray diffraction revealed that for the palladium, palladium oxide was active in promoting the oxidation of all tested hydrocarbons at a lower temperature than platinum. That was not the case for nanoparticles, as the temperature was not sufficiently high to oxidize the surface. The obtained results help understand the catalytic oxidation of the tested hydrocarbons under different conditions and help optimize the operation parameters for catalysts.

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“…As discussed before in zeta potentials, PAW's zeta potential was the most negative one. This suggests that its electrondoping structure was the richest one, which might favor the reduction (disfavor the oxidation) of the reversible oxidation and reduction reactions of Fe(CN) 6 3−/4− performed in PAW.…”

Section: Distinct Activities Of Pv1 (Or Pv2) On Catalyzed Electrochem...mentioning

confidence: 99%

“…[1][2][3][4] Interestingly, HB-free water vapor is active, which can markedly promote many gas-phase reactions. [5][6][7] As reported by Li et al, 8 in nature, the pervasive presence of water with unique properties is utilized to control many enzymatic reactions for regulating selectivity and reaction rates and facilitate proton transfer. [9][10][11] On the other hand, some chemical reactions were observed to be promoted in liquid water with unique intermolecular HBs.…”

Section: Introductionmentioning

confidence: 99%