Experimental and modeling study of CO and hydrocarbons light-off on various Pt-Pd/γ-Al 2 O 3 diesel oxidation catalysts

Daneshvar, Keyvan; Dadi, Rama Krishna; Luss, Dan; Balakotaiah, Vemuri; Kang, Sung Bong; Kalamaras, Christos M.; Epling, William S.

doi:10.1016/j.cej.2017.04.078

Cited by 37 publications

(20 citation statements)

References 41 publications

(77 reference statements)

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“…From Figs. 2a and 3a, it can also be noted that CO lightoff curves of the Ce/Mn catalysts display a shoulder in the conversion profile, due to a slight decrease in the reaction rate within the temperature range of 450 K and 500 K. This can be attributed to the competitive adsorption between CO and hydrocarbons; particularly as intermediate species are formed on the surface during C 3 H 6 oxidation in the presence of NOx [7,10]. This shoulder is not observed in the CO light-off curves of OMS-2:60 ( Fig.…”

Section: Effect Of Ceria Incorporationmentioning

confidence: 92%

Doping Manganese Oxides with Ceria and Ceria Zirconia Using a One-Pot Sol–Gel Method for Low Temperature Diesel Oxidation Catalysts

et al. 2020

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Octahedral molecular sieves (OMS-2) are an interesting form of manganese oxide with a 2 × 2 edge sharing tunnel structure and a cation positioned inside. Cryptomelane is an OMS-2 material with K + cations within the crystalline tunnel and has been widely used in catalytic oxidation reactions, due to a mixed valency of Mn 3+ and Mn 4+ cations. Cryptomelane (K-OMS-2) can be modified by structural incorporation of various dopants and tunnel cations which can enhance the catalytic activity of the material. It also offers to be a promising alternative material for the low temperature emission control of combustion vehicles; particularly during cold start and low temperature conditions of diesel vehicles. In this work we used a one-pot solgel route to synthesize a range of manganese oxide based supports doped with Ce and CeZrO 2 , as alternative low temperature diesel oxidation catalysts. We have investigated the combination of manganese, ceria and zirconia in mixed oxide catalyst supports. The synthesized samples were loaded with 1 wt% Pt and their activity in the oxidation reactions of CO and C 3 H 6 , were compared with a commercial diesel oxidation catalyst with the same metal loading. The reductions in CO and C 3 H 6 oxidation temperature T 50 of 109 K and 81 K respectively was achieved compared to a commercial diesel oxidation catalyst.

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Section: Effect Of Ceria Incorporationmentioning

confidence: 92%

Doping Manganese Oxides with Ceria and Ceria Zirconia Using a One-Pot Sol–Gel Method for Low Temperature Diesel Oxidation Catalysts

et al. 2020

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“…Among them, Pt is widely used in DOCs, and the addition of Pd was shown to increase the thermal stability and sintering resistance of the catalyst [1]. As PGMs are high cost components of ATSs, several efforts have concentrated on decreasing the amount of PGMs and increasing the stability and efficiency of PGMs by preparing DOCs with different PGM loadings, ratios, or particle sizes [3][4][5][6][7][8][9][10], and using different synthesis techniques [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

“…For bimetallic PtPd/Al2O3 catalysts, the results of the reports in the literature indicate that there is a certain Pt:Pd ratio range resulting in the optimum performance for the NO and hydrocarbon oxidation reactions while maintaining high durability upon ageing [8,9]. For example, Shakya et al compared PtPd/Al2O3 catalysts with Pt:Pd molar ratios of 1:5.7, 1:1.9, 1.6:1, and 5.7:1 for NO, CO and hydrocarbon oxidation reactions.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Pt/Al2O3 and PtPd/Al2O3 catalysts by supercritical deposition and their performance for oxidation of nitric oxide and propene

et al. 2022

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“…6,[11][12][13] Additional catalyst optimization emerges in the study of bimetallic Pt-Pd catalysts with different studies reporting various optimal Pt:Pd ratios. [14][15][16] Even for a nominal alloy catalyst composition, single particle nanostructure could vary between random alloys, core-shell and phase segregated structures, and intermetallic structures, each with their own catalytic reactivity. The development of structure-property relationships for emissions control materials will help facilitate the rapid design of improved catalysts.…”

Section: Introductionmentioning

confidence: 99%

Palladium oxidation leads to methane combustion activity: Effects of particle size and alloying with platinum

Goodman

Aitbekova

et al. 2019

The Journal of Chemical Physics

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Pd-and Pt-based catalysts are highly studied materials due to their widespread use in emissions control catalysis. However, claims continue to vary regarding the active phase and oxidation state of the metals. Different conclusions have likely been reached due to the heterogeneous nature of such materials containing various metal nanoparticle sizes and compositions, which may each possess unique redox features. In this work, using uniform nanocrystal catalysts, we study the effect of particle size and alloying on redox properties of Pd-based catalysts and show their contribution to methane combustion activity using operando quick extended x-ray absorption fine structure measurements. Results demonstrate that for all studied Pd sizes (3 nm-16 nm), Pd oxidation directly precedes CH 4 combustion to CO 2 , suggesting Pd oxidation as a prerequisite step to methane combustion, and an oxidation pretreatment shows equal or better catalysis than a reduction pretreatment. Results are then extended to uniform alloyed PtxPd 1−x nanoparticles, where oxidative pretreatments are shown to enhance low-temperature combustion. In these uniform alloys, we observe a composition-dependent effect with Pt-rich alloys showing the maximum difference between oxidative and reductive pretreatments. In Pt-rich alloys, we initially observe that the presence of Pt maintains Pd in a lower-activity reduced state. However, with time on stream, PdO eventually segregates under oxidizing combustion conditions, leading to a slowly increasing activity. Overall, across particle sizes and alloy compositions, we relate increased catalytic activity to Pd oxidation, thus shedding light on previous contrasting results related to the methane combustion activity of these catalysts.

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Experimental and modeling study of CO and hydrocarbons light-off on various Pt-Pd/γ-Al 2 O 3 diesel oxidation catalysts

Cited by 37 publications

References 41 publications

Doping Manganese Oxides with Ceria and Ceria Zirconia Using a One-Pot Sol–Gel Method for Low Temperature Diesel Oxidation Catalysts

Doping Manganese Oxides with Ceria and Ceria Zirconia Using a One-Pot Sol–Gel Method for Low Temperature Diesel Oxidation Catalysts

Preparation of Pt/Al2O3 and PtPd/Al2O3 catalysts by supercritical deposition and their performance for oxidation of nitric oxide and propene

Palladium oxidation leads to methane combustion activity: Effects of particle size and alloying with platinum

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