Design considerations for low-temperature hydrocarbon oxidation reactions on Pd based catalysts

Xiong, Haifeng; Wiebenga, Michelle H.; Carrillo, Cristihan; Gaudet, Jason R.; Pham, Hien N.; Kunwar, Deepak; Oh, Se H.; Qi, Gongshin; Kim, Chang Hwan; Datye, Abhaya K.

doi:10.1016/j.apcatb.2018.05.049

Cited by 108 publications

(68 citation statements)

References 25 publications

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“…The absence of metallic Pd in both catalysts is due to lower calcination temperature of 500 • C and decomposition temperature of PdO is higher than 700 • C [25]. Our results are contrary to previous studies which report the presence of Pd in such catalysts [23,[26][27][28]. XPS data were also collected for the two catalysts after reaction with 1% methane, 4% oxygen and balance helium at 450 • C for 24 h. There was no significant change in the relative amounts of PdO and PdO x after reaction (Figure 1b,d).…”

Section: X-ray Photoelectron Spectroscopy (Xps)contrasting

confidence: 99%

Comparative Study of the Characteristics and Activities of Pd/γ-Al2O3 Catalysts Prepared by Vortex and Incipient Wetness Methods

et al. 2019

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5 wt% Pd/γ-Al2O3 catalysts were prepared by a modified Vortex Method (5-Pd-VM) and Incipient Wetness Method (5-Pd-IWM), and characterized by various techniques (Inductively coupled plasma atomic emission spectroscopy (ICP-AES), N2-physisorption, pulse CO chemisorption, temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), and X-ray diffraction (XRD)) under identical conditions. Both catalysts had similar particle sizes and dispersions; the 5-Pd-VM catalyst had 0.5 wt% more Pd loading (4.6 wt%). The surfaces of both catalysts contained PdO and PdOx with about 7% more PdOx in 5-Pd-VM. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and scanning electron microscope (SEM) images indicated presence of PdO/PdOx nanocrystals (8–10 nm) on the surface of the support. Size distribution by STEM showed presence of smaller nanoparticles (2–5 nm) in 5-Pd-VM. This catalyst was more active in the lower temperature range of 275–325 °C and converted 90% methane at 325 °C. The 5-Pd-VM catalyst was also very stable after 72-hour stability test at 350 °C showing 100% methane conversion, and was relatively resistant to steam deactivation. Hydrogen TPR of 5-Pd-VM gave a reduction peak at 325 °C indicating weaker interactions of the oxidized Pd species with the support. It is hypothesized that smaller particle sizes, uniform particle distribution, and weaker PdO/PdOx interactions with the support may contribute to the higher activity in 5-Pd-VM.

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Section: X-ray Photoelectron Spectroscopy (Xps)contrasting

confidence: 99%

Comparative Study of the Characteristics and Activities of Pd/γ-Al2O3 Catalysts Prepared by Vortex and Incipient Wetness Methods

et al. 2019

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“…XPS did not show any peak for elemental Pd, thereby confirming the absence of metallic palladium in the catalyst. This result is in contrast to previous research reports on the presence of metallic Pd in Pd/γ-Al2O3 catalysts [18][19][20]26]. In addition to metallic Pd and stoichiometric PdO, palladium surfaces exhibit non-stoichiometric native oxides.…”

Section: X-ray Photoelectron Spectroscopy (Xps)contrasting

confidence: 56%

Low-Temperature Activity and PdO-PdOx Transition in Methane Combustion by a PdO-PdOx/γ-Al2O3 Catalyst

et al. 2018

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Abstract:The search to discover a suitable catalyst for complete combustion of methane at low temperature continues to be an active area of research. We prepared a 5 wt % PdO-PdO x /γ-Al 2 O 3 catalyst by a modified Vortex-assisted Incipient Wetness Method. X-ray Photoelectron Spectroscopy showed that the original catalyst contained PdO (38%) and PdO x (62%) on the surface and indicated that PdO x originated from the interaction of PdO with the support. Scanning Transmission Electron Microscopy confirmed the catalyst had an average particle size of 10 nm and was well-dispersed in the support. The catalyst exhibited exceptional low-temperature activities with 90-94% methane conversion at 300-320 • C. The catalyst was active and stable after several catalytic runs with no signs of deactivation by steam in this narrow temperature range. However, the conversion decreased in the temperature range 325-400 • C. The surface composition changed to some extent after the reaction at 325 • C. A tentative mechanism proposes PdO x (Pd native oxide) as the active phase and migration of oxide ions from the support to PdO and then to PdO x during the catalytic oxidation. The high methane conversion at low temperature is attributed to the vortex method providing better dispersion, and to catalyst-support interaction producing the active phase of PdO x .

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“…CNTs, especially multi-walled carbon nanotubes (MWCNTs) and N-doped bamboo-shaped carbon nanotubes (NBCNTs), are often used as promising support material to stabilize Pt nanoparticles and are applied in catalytic reactions such as hydrocarbon oxidation [8] or hydrogenation reactions [9] owing to their high specific surface area [10] and excellent thermal conductivity parameters [11]. Using fibrous cellulose as a support of the carbon nanotubes, membrane layer can be formed, which provides longer and more efficient contact between the catalytic nanoparticles and gas molecules.…”

Section: Graphic Abstract Introductionmentioning

confidence: 99%

Catalytic hydrogenation of n-butene with nanosized Pt/NBCNT hybrid membranes reinforced with bacterial cellulose

et al. 2020

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One of the main challenges in the field of heterogeneous catalysis is the involvement of thin solid films and membranes and their application in flow systems. In this regard, we report here the application of self-supported bacterial cellulose (BC) reinforced nanosized platinum (Pt)/N-doped bamboo-like carbon nanotube (NBCNT) hybrid catalyst membrane with a thickness of 35 ± 5 µm in the hydrogenation of n-butene. To synthetized the BC-NBCNT/Pt nanohybrid membrane catalyst a simple impregnation route was applied in a two-step process. As-prepared material was tested in a continuous flow system and the conversion was followed directly by using Fourier transform infrared spectroscopy. Furthermore, the fabricated films were characterized by scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and specific surface area measurement (Brunauer–Emmett–Teller). Hydrogenation performance was studied on both single and double films. Results revealed that 97% conversion of n-butene can be achieved using these bacterial cellulose reinforced hybrid membranes. Graphic abstract

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Design considerations for low-temperature hydrocarbon oxidation reactions on Pd based catalysts

Cited by 108 publications

References 25 publications

Comparative Study of the Characteristics and Activities of Pd/γ-Al2O3 Catalysts Prepared by Vortex and Incipient Wetness Methods

Comparative Study of the Characteristics and Activities of Pd/γ-Al2O3 Catalysts Prepared by Vortex and Incipient Wetness Methods

Low-Temperature Activity and PdO-PdOx Transition in Methane Combustion by a PdO-PdOx/γ-Al2O3 Catalyst

Catalytic hydrogenation of n-butene with nanosized Pt/NBCNT hybrid membranes reinforced with bacterial cellulose

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