A detailed spectroscopic analysis of the growth of oxy-carbon species on the surface of Pt/Al2O3 during propane oxidation

O’Brien, Casey P.; Lee, Ivan C.

doi:10.1016/j.jcat.2016.12.021

Cited by 53 publications

(46 citation statements)

References 56 publications

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“…(1) higher reactivity enolate, aliphatic ester, and acetone (EEA) species and (2) lower reactivity acetate species. This simplification is justified by our results reported in a previous publication, 6 which showed that acetate species are removed from the surface during TPO at significantly higher temperature than EEA species, which are all removed at similar temperatures. TPO profiles were simulated using three different types of kinetic rate expressions with different reaction orders with respect to the surface carbon concentration (first-order, second-order, and power-law): first-order:…”

Section: Methodssupporting

confidence: 51%

“…This work completes a series of three papers 6,9 examining the many different surface reactions occurring on Pt/Al 2 O 3 during propane oxidation. These surface reactions include: (1) complete oxidation of propane to CO 2 and H 2 O on the The experimental CO 2 evolution rates (gray lines) were simulated using the second-order kinetic model, eq 9, with kinetic parameters listed in Table 2.…”

Section: Methodsmentioning

confidence: 84%

“…The simulated CO 2 evolution rates (black lines) were calculated from the sum of the CO 2 evolution rates from oxidation of acetate (red lines) and enolate, ester, and acetone species (blue lines). 6 The most important factor governing the kinetics of the reaction is the oxygen coverage on the platinum nanoparticles. As the oxygen coverage on the nanoparticles increases with increasing O 2 /C 3 H 8 ratio and decreasing temperature, the propane oxidation rate decreases.…”

Section: Methodsmentioning

confidence: 99%

“…In our previous work, 6 we characterized the growth of carbonaceous species on the surface of Pt/Al 2 O 3 during propane oxidation, including their composition and their location on the catalyst surface, using diffuse-reflectance infrared Fourier-transform spectroscopy (DRIFTS). We showed that many different oxygenated carbonaceous (oxycarbon) surface species spillover from the platinum nanoparticles and grow on the Al 2 O 3 support.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic Modeling of Spillover and Temperature-Programmed Oxidation of Oxy-Carbon Surface Species on Pt/Al₂O₃

O’Brien

Lee

2017

J. Phys. Chem. C

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During propane oxidation over Pt/Al2O3 in the 200–300 °C temperature range, many different oxygenated carbonaceous (oxy-carbon) surface species spillover from the platinum nanoparticles and grow on the Al2O3 support. The rate of oxy-carbon species growth on the Pt/Al2O3 surface is consistent with a diffusion-limited process where the rate of oxy-carbon species diffusion on the Al2O3 support is the rate-determining step. A model based on Fick’s second law for two-dimensional radial diffusion is used to analyze the kinetics of oxy-carbon species spillover on the Al2O3 support. An Arrhenius expression describing the rate of oxy-carbon species diffusion on the Al2O3 support, which has a pre-exponential factor of 7.9 × 10–14 cm2/s and an activation barrier of 24 kJ/mol, was extracted from the kinetic analysis. Following propane oxidation, the oxy-carbon surface species were completely oxidized to CO2 during temperature-programmed oxidation (TPO). During TPO of the oxy-carbon species, diffusion of the oxy-carbon species on the Al2O3 support is relatively fast, and a surface reaction on the platinum nanoparticles is the rate-determining step. TPO of oxy-carbon surface species was simulated using surface reaction rate expressions with three different reaction orders with respect to the surface carbon concentration (first-order, second-order, and power-law). The kinetics of TPO of the oxy-carbon surface species is most accurately represented by second-order kinetic rate expressions with activation barriers of 147 kJ/mol for oxidation of acetate species and 112 kJ/mol for oxidation of higher reactivity enolate, aliphatic ester, and acetone species. Formation of platinum oxides during propane oxidation increase the activity of the catalyst for TPO of the oxy-carbon species. This work reveals quantitative mechanistic insights into both the carbon growth and burnoff processes, which is important for designing efficient hydrocarbon conversion processes.

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Section: Methodssupporting

confidence: 51%

Section: Methodsmentioning

confidence: 84%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetic Modeling of Spillover and Temperature-Programmed Oxidation of Oxy-Carbon Surface Species on Pt/Al₂O₃

O’Brien

Lee

2017

J. Phys. Chem. C

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“…first clearly appeared at 250 • C. With further increments in temperature, the Pt-NCO vibrational bands showed an increase in intensity and a shift towards higher wavenumbers, reaching 2150 cm −1 at 500 • C, while the band at 2048 cm −1 assigned to Pt-CO species shifted toward 2040 cm −1 at 450 • C and disappeared at 500 • C. The blue-shift of v s (NCO) reflects increasing NCO coverage, due to the further transformation of HOCH 2 CH 2 NH 3 + species. In addition, three were also the formation of some surface oxy-carbon species, including enolates (1392 cm −1 , v s (CH 2 =CH-O))[32], and formates (1377 cm −1 , v s (COO))[33] in the temperature regions of 250~400 • C. According to TG and in situ DRIFTS results, the thermal decomposition process of Pt-precursor can be summarized as the following reaction (I):…”

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confidence: 99%

In Situ Investigations on the Facile Synthesis and Catalytic Performance of CeO2-Pt/Al2O3 Catalyst

Wang

Ren

et al. 2020

Catalysts

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Ceria-modified Pt/Al2O3 catalyst has been commonly prepared by the impregnation of platinum on ceria-modified alumina and widely applied in the chemical industry and automotive industry. The in situ diffuse reflectance infrared Fourier transformed spectroscopy (DRIFTS), and thermogravimetric (TG) analysis techniques were employed to investigate the typical mechanisms of the bis(ethanolammonium)hexahydroxyplatinate(IV) and cerium nitrate decomposition catalyzed by Ptδ+ species for the facile synthesis of CeO2-Pt/Al2O3 catalyst. It was found that Pt4+-catalyzed decomposition of cerium nitrate leads to the higher dispersity of ceria and forming more active oxygen species, on the basis of X-ray diffraction (XRD) and H2 temperature-programmed reduction (H2-TPR) results. The in situ activity measurements were also performed to investigate the reaction mechanisms and the specific activities for the catalytic CO, NO, C3H6 and C3H8 co-oxidation. The results indicate that undesirable N2O by-product is formed by the selective catalytic reduction (SCR) of NO by C3H6 below 350 °C. The cerium addition effectively improves the activity of catalytic oxidation, but exhibits an increased N2O yield, due to the increased reducibility.

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Activation of Surface Lattice Oxygen in Ceria Supported Pt/Al₂O₃ Catalyst for Low‐Temperature Propane Oxidation

Wang

Feng

et al. 2019

ChemCatChem

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The synergy between active Pt species and ceria results in the presence of more coordinately unsaturated Pt2+ and Pt4+ species, which were found to be critical to drive C− and C−H bonds activation and enhance propane oxidation. Surface lattice oxygen on ceria in the vicinity of electron‐deficient Pt species provides the enhanced reactivity for low‐temperature propane oxidation. The reducibility and amount of activated surface oxygen species play a significant role in improving the reaction rates of propane oxidation in the 150∼300 °C temperature range. Ceria effectively promotes oxidative redispersion of platinum crystallites supported on alumina during propane oxidation in O2‐rich conditions, due to the unique ability to trap and stabilize ionic platinum.

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A detailed spectroscopic analysis of the growth of oxy-carbon species on the surface of Pt/Al2O3 during propane oxidation

Cited by 53 publications

References 56 publications

Kinetic Modeling of Spillover and Temperature-Programmed Oxidation of Oxy-Carbon Surface Species on Pt/Al₂O₃

Kinetic Modeling of Spillover and Temperature-Programmed Oxidation of Oxy-Carbon Surface Species on Pt/Al₂O₃

In Situ Investigations on the Facile Synthesis and Catalytic Performance of CeO2-Pt/Al2O3 Catalyst

Activation of Surface Lattice Oxygen in Ceria Supported Pt/Al₂O₃ Catalyst for Low‐Temperature Propane Oxidation

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A detailed spectroscopic analysis of the growth of oxy-carbon species on the surface of Pt/Al2O3 during propane oxidation

Cited by 53 publications

References 56 publications

Kinetic Modeling of Spillover and Temperature-Programmed Oxidation of Oxy-Carbon Surface Species on Pt/Al2O3

Kinetic Modeling of Spillover and Temperature-Programmed Oxidation of Oxy-Carbon Surface Species on Pt/Al2O3

In Situ Investigations on the Facile Synthesis and Catalytic Performance of CeO2-Pt/Al2O3 Catalyst

Activation of Surface Lattice Oxygen in Ceria Supported Pt/Al2O3 Catalyst for Low‐Temperature Propane Oxidation

Contact Info

Product

Resources

About

Kinetic Modeling of Spillover and Temperature-Programmed Oxidation of Oxy-Carbon Surface Species on Pt/Al₂O₃

Kinetic Modeling of Spillover and Temperature-Programmed Oxidation of Oxy-Carbon Surface Species on Pt/Al₂O₃

Activation of Surface Lattice Oxygen in Ceria Supported Pt/Al₂O₃ Catalyst for Low‐Temperature Propane Oxidation