Promotion of a Pd/Al2O3 close-coupled catalyst by Ni

Fang, Ruimei; Cui, Yajuan; Shi, Zhuqun; Gong, Maochu; Chen, Yaoqiang

doi:10.1016/s1872-2067(15)60850-6

Cited by 12 publications

(5 citation statements)

References 33 publications

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“…The first consists to bring the DOC or TWC more quickly to the activation temperature, using passive or active systems. These systems are − (a) electrically heated catalysts to provide a quick warm-up of the converter, (b) close-coupled catalysts (the converter is placed very close to the engine but the additional heat provided may deteriorate the catalyst with time); (c) a precatalyst, i.e., a small DOC more loaded with precious metals than the main one in order to provide an exotherm to lower the light-off temperature of the main DOC. The second and more promising solution consists in improving the design of the HC converter, by adding zeolitic materials, which act as an HC trap, to the washcoat …”

Section: Introductionmentioning

confidence: 99%

Impact of the Zeolite Structure and Acidity on the Adsorption of Unburnt Hydrocarbons Relevant to Cold Start Conditions

Westermann

Azambre

2016

J. Phys. Chem. C

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Adsorption behavior of commercial zeolites were investigated for the trapping of a hydrocarbon mixture (propene, toluene and decane) mimicking Diesel cold start exhausts under dry conditions. The studied commercial zeolites, in most cases under protonated form, (with Si/Al ratio in the range 2−15) present different structures: FAU, *BEA, MOR, MFI, FER, and LTA. Textural and structural characterizations were carried out using N 2 adsorption at −196 °C and X-ray diffraction. In situ FTIR spectroscopy of adsorbed pyridine was used to probe quantitatively the acid sites. The methodology used in this study consisted of an adsorption phase at 35 °C followed by temperature-programmed desorption (TPD) under He at 10 °C/min, and three different adsorption mechanisms were highlighted according to the pore size and the host framework. MOR and MFI structures appear to be the less selective for any type of hydrocarbon and are thus the most suitable for cold start applications. Except for these types of zeolites presenting a "single-file diffusion" mechanism, propene often desorbs at low temperatures or is adsorbed very little. By contrast, heavier hydrocarbons such as toluene and decane desorb at temperatures that match with threeway catalyst (TWC) or Diesel oxidation catalyst (DOC) light-off temperatures.

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Section: Introductionmentioning

confidence: 99%

Impact of the Zeolite Structure and Acidity on the Adsorption of Unburnt Hydrocarbons Relevant to Cold Start Conditions

Westermann

Azambre

2016

J. Phys. Chem. C

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“…The wet-chemical synthesis of the NPs enabled a better control over the size in comparison with the traditional synthesis methods such as impregnation, co-precipitation, or deposition–precipitation. The NPs were supported on alpha-Al 2 O 3 powders by a standard dispersion procedure . Alpha-Al 2 O 3 is a support with a high surface area and high thermal stability.…”

Section: Results and Discussionmentioning

confidence: 99%

“…The NPs were supported on alpha-Al 2 O 3 powders by a standard dispersion procedure . Alpha-Al 2 O 3 is a support with a high surface area and high thermal stability. This support also features strong interaction with noble metals .…”

Section: Results and Discussionmentioning

confidence: 99%

Lattice Strain and Surface Activity of Ternary Nanoalloys under the Propane Oxidation Condition

Kareem

Maswadeh

et al. 2022

ACS Appl. Mater. Interfaces

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The ability to harness the catalytic oxidation of hydrocarbons is critical for both clean energy production and air pollutant elimination, which requires a detailed understanding of the dynamic role of the nanophase structure and surface reactivity under the reaction conditions. We report here findings of an in situ/operando study of such details of a ternary nanoalloy under the propane oxidation condition using high-energy synchrotron X-ray diffraction coupled to atomic pair distribution function (HE-XRD/PDF) analysis and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The catalysts are derived by alloying Pt with different combinations of second (Pd) and third (Ni) transition metals, showing a strong dependence of the catalytic activity on the Ni content. The evolution of the phase structure of the nanoalloy is characterized by HE-XRD/PDF probing of the lattice strain, whereas the surface activity is monitored by DRIFTS detection of the surface intermediate formation during the oxidation of propane by oxygen. The results reveal the dominance of the surface intermediate species featuring a lower degree of oxygenation upon the first C–C bond cleavage on the lower-Ni-content nanoalloy and a higher degree of oxygenation upon the second C–C bond cleavage on the higher-Ni-content nanoalloy. The face-centered-cubic-type phase structures of the nanoalloys under the oxidation condition are shown to exhibit Ni-content-dependent changes of lattice strains, featuring the strongest strain with little variation for the higher-Ni-content nanoalloy, in contrast to the weaker strains with oscillatory variation for the lower-Ni-content nanoalloys. This process is also accompanied by oxygenation of the metal components in the nanoalloy, showing a higher degree of oxygenation for the higher-Ni-content nanoalloy. These subtle differences in phase structure and surface activity changes correlate with the Ni-composition-dependent catalytic activity of the nanoalloys, which sheds a fresh light on the correlation between the dynamic change of atomic strains and the surface reactivity and has significant implications for the design of oxidation catalysts with enhanced activities.

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“…The low temperature C 3 H 8 oxidation has been investigated employing platinum catalysts on different supports (MgO, La 2 O 3 , Al 2 O 3 , ZrO 2 , SiO 2 , SiO 2 -Al 2 O 3 and SO 4 2− -ZrO 2 ), and the best results were given by Pt/ Al 2 O 3 -SiO 2 mixed oxide [23]. It is worth mentioning that propane has been used as a model hydrocarbon molecule because it is very stable and as consequence, difficult to oxidize, and in the presence of heat or light, the reaction involves the breaking of C-H and C-C bonds [23][24][25]. On the other hand, the development of bimetallic catalysts is considered as a promising alternative in terms of stability and high activity with regard to monometallic catalysts for C 3 H 8 and CO oxidation; for example, the AuPd nanoalloy supported on a Mo(110) substrate has shown high catalytic activity and improved stability toward the C 3 H 8 oxidation [24].…”

Section: Introductionmentioning

confidence: 99%

“…Regarding the support, the reducible ones such as TiO 2 and CeO 2 have exhibited significant positive effects on the catalytic activity of Pd, Pt, Rh, PdRh metal nanoparticles during the C 3 H 8 oxidation due to their ability to provide reactive oxygen [25]. However, to achieve better catalytic activity, it is necessary to improve the ability of the oxide to provide reactive oxygen, mainly in the case of TiO 2 .…”

Section: Introductionmentioning

confidence: 99%

Catalytic Oxidation of Propane and Carbon Monoxide by Pd Nanoparticles on Mn/TiO2 Catalysts

2023

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The present work shows experimental results on the catalytic oxidation of C3H8 and CO by Pd nanoparticles supported on MnOx/TiO2 synthesized by the sol–gel method. The results show a strong interaction between Pd and MnOx/TiO2; likewise, the annealing temperature of the TiO2 support modified the catalytic properties of the Pd–MnOx/TiO2 catalyst. In this line, the catalysts with 1 and 2 wt% of Pd loading supported on MnOx/TiO2 showed outstanding catalytic activity oxidizing C3H8 and CO within two temperature intervals: 200–400 °C and 25–200 °C, respectively. The Pd–MnOx/TiO2 catalyst also displayed very high stability during long-term tests and the addition of Pd nanoparticles reduced greatly the oxidation temperature of MnOx/TiO2. The outcomes revealed that the Pd–Mn interaction promoted the formation of new Pd0/Pd2+ active sites as well as the formation of oxygen vacancies and reduced Ti4+ to Ti3+ species, which led to the improvement of the Mn3+ and Mn4+ redox features, thus boosting the catalytic oxidation capacity of the Pd–MnOx/TiO2 catalyst. Graphical Abstract

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Promotion of a Pd/Al2O3 close-coupled catalyst by Ni

Cited by 12 publications

References 33 publications

Impact of the Zeolite Structure and Acidity on the Adsorption of Unburnt Hydrocarbons Relevant to Cold Start Conditions

Impact of the Zeolite Structure and Acidity on the Adsorption of Unburnt Hydrocarbons Relevant to Cold Start Conditions

Lattice Strain and Surface Activity of Ternary Nanoalloys under the Propane Oxidation Condition

Catalytic Oxidation of Propane and Carbon Monoxide by Pd Nanoparticles on Mn/TiO2 Catalysts

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