Deactivation of postcombustion catalysts, a review

Neyestanaki, Ahmad Kalantar; Klingstedt, Fredrik; Salmi, Tapio; Murzin, Dmitry Yu.

doi:10.1016/j.fuel.2003.09.002

Cited by 180 publications

(101 citation statements)

References 54 publications

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“…This behaviour has been yet observed with different Ptbased catalysts (see e.g. [29]) and explained by a decrease of concentration of small PtO particles, leading to higher activity.…”

Section: -Effect Of Noble Metals Additionmentioning

confidence: 60%

Effect of sulphur poisoning on perovskite catalysts prepared by flame-pyrolysis

Rossetti

Buchneva

Biffi

et al. 2009

Applied Catalysis B: Environmental

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ABO3 perovskite-like catalysts are known to be sensitive to sulphur-containing compounds. Possible solutions to increase resistance to sulphur are represented by either catalyst bed protection with basic guards or catalyst doping with different transition or noble metals. In the present work La(1-x)A'xCoO3, La(1-x)A'xMnO3 and La(1-x)A'xFeO3, with A' = Ce, Sr and x=0, 0.1, 0.2, either pure or doped with noble metals (0.5 wt% Pt or Pd), were prepared in nano-powder form by flame pyrolysis. All the catalysts were tested for the catalytic flameless combustion of methane, monitoring the activity by on-line mass spectrometry. The catalysts were then progressively deactivated in operando with a new procedure, consisting of repeated injection of some doses of tetrahydrothiophene (THT), usually employed as odorant in the natural gas grid, with continuous analysis of the transient response of the catalyst. The activity tests were then repeated on the poisoned catalyst. Different regenerative treatments were also tried, either in oxidising or reducing atmosphere.Among the unsubstituted samples, higher activity and better resistance to poisoning have been observed in general with manganites with respect to the corresponding formulations containing Co or Fe at the B-site. The worst catalyst showed LaFeO3, from both the points of view of activity and of resistance to sulphur * Corresponding author: fax +39-02-50314300, e-mail ilenia.rossetti@unimi.it 2 poisoning. La0,9Sr0,1MnO3 showed, the best results, exhibiting very high activity and good resistance even after the addition of up to 8.4 mg of THT per g of catalyst.Interesting results were attained also by adding Sr to Co-based perovskites. Sr showed a first action by forcing Mn or Co in their highest oxidation state, but, in addition, it could also act as a sulphur guard, likely forming stable sulphates due to its basicity. Among noble metals, Pt doping proved beneficial in improving the activity of both the fresh and the poisoned catalyst.Keywords: Methane, catalytic combustion; Sulphur poisoning; Perovskite-like catalysts. -INTRODUCTIONThe catalytic flameless combustion (CFC) of methane outperforms conventional flame combustion because of lower emission of pollutants (HC, CO and NOx) and high thermal efficiency. The catalysts traditionally used for CFC are mainly based on supported noble metals, such as Pd and Pt, which ensure high activity, however accompanied by some drawbacks, due to high cost and poor thermal and chemical stability. La-based catalysts with ABO3 perovskite-like structure [1][2][3][4] have been proposed as a valid alternative for the present application. Indeed, perovskite catalysts combine low cost, thermo-chemical stability at high operating temperature and satisfactory catalytic activity [5][6][7][8]. In spite of this, there are still some open questions, especially regarding their resistance to sulphur poisoning when used for the CFC of methane. Indeed, the poisoning mechanism of perovskite-like catalysts has not been completely understood a...

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“…This behaviour has been yet observed with different Ptbased catalysts (see e.g. [29]) and explained by a decrease of concentration of small PtO particles, leading to higher activity.…”

Section: -Effect Of Noble Metals Additionmentioning

confidence: 60%

Effect of sulphur poisoning on perovskite catalysts prepared by flame-pyrolysis

Rossetti

Buchneva

Biffi

et al. 2009

Applied Catalysis B: Environmental

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“…Most of the studies focus on the Pd/PdO activity for CH 4 conversion, as this is currently a main application of Pd-only catalysts. Although it is widely assumed that PdO is the more active form [7,8], results exist that favor Pd to be more active [9]. Especially for CO-only, higher activity for Pd compared to PdO has already been found [10].…”

Section: No-oxidationmentioning

confidence: 99%

Hysteresis Phenomena on Platinum and Palladium-based Diesel Oxidation Catalysts (DOCs)

Dubbe

Bühner

Eigenberger

et al. 2016

Emiss. Control Sci. Technol.

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The diesel oxidation catalyst (DOC) plays a key role in diesel exhaust treatment systems. Typical noble metals used as active components are platinum (Pt) and palladium (Pd). During lightoff/lightout experiments, the catalyst reactivity during heating is in some cases different from the reactivity during cooling in the same reaction mixture. These so called hysteresis phenomena have repeatedly been reported for CO, NO, and HC conversion and are mostly attributed to noble metal oxidation and/or surface coverage effects. Hauff et al. have developed a kinetic model that is able to account for the hysteresis effects observed in NO conversion on Pt-only catalysts due to noble metal oxidation. The model was only validated for a limited range of NO concentrations and temperatures. In this follow-up, further experiments on Pt-only as well as on Pd-only catalysts will be presented for additional feed compositions. General transferability of the Pt-only model to Pd-only catalysts for NO-only is demonstrated. By addition of CO and propene to the feed, additional hysteresis phenomena are observed and will be discussed. On Pd-only, results indicate that under lean exhaust conditions, the noble metal can only be slightly reduced by CO. Interestingly, with a mix of CO and NO no reactivation is observed whereas the combination of CO, NO, and propene again shows reducing tendency. Based on these informations, a possible modeling approach will be proposed.

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“…However, with NO 2 , the reaction occurs at significantly lower temperatures [3], thus many filters have DOCs upstream as well. DOCs containing Pt are more active for oxidation reactions than those containing just Pd [4], but pure Pt sinters more rapidly in an oxidizing environment compared to Pt/Pd formulations [5,6] and therefore these are often studied.…”

Section: Introductionmentioning

confidence: 99%

Spatial Resolution of Reactant Species Consumption in Diesel Oxidation Catalysts

2009

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Oxidation reactions over a model monolithsupported Pt-Pd/Al 2 O 3 diesel oxidation catalyst were characterized as a function of temperature and position within the catalyst using spatially resolved capillary-inlet mass spectrometry (SpaciMS). The data obtained demonstrate that H 2 and CO are oxidized prior to C 3 H 6 and C 12 H 26 and clearly show back-to-front ignition of the reductant species. Significant NO oxidation was observed simultaneous to dodecane light-off, likely related to dodecane partial oxidation products.

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Deactivation of postcombustion catalysts, a review

Cited by 180 publications

References 54 publications

Effect of sulphur poisoning on perovskite catalysts prepared by flame-pyrolysis

Effect of sulphur poisoning on perovskite catalysts prepared by flame-pyrolysis

Hysteresis Phenomena on Platinum and Palladium-based Diesel Oxidation Catalysts (DOCs)

Spatial Resolution of Reactant Species Consumption in Diesel Oxidation Catalysts

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