Carbonate‐Promoted Catalytic Activity of Potassium Cations for Soot Combustion by Gaseous Oxygen

Ogura, Masaru; Kimura, Riichiro; Ushiyama, Hiroshi; Nikaido, Fumiya; Yamashita, Koichi; Okubo, Tatsuya

doi:10.1002/cctc.201300736

Cited by 29 publications

(28 citation statements)

References 73 publications

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“…The addition of alkali often leads to strong enhancement of their catalytic activity [6][7][8][9]. Likewise, alkali promotion of catalysts for soot oxidation is reported to have a strong effect as shown in [3,10,11,12,13,14,15]. It is worth mentioning that the alkali cations may be located on the surface of the oxide material or intercalated into its structure.…”

Section: Introductionmentioning

confidence: 99%

Surface versus bulk alkali promotion of cobalt-oxide catalyst in soot oxidation

Jakubek

Kaspera

Legutko

et al. 2015

Catalysis Communications

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Section: Introductionmentioning

confidence: 99%

Surface versus bulk alkali promotion of cobalt-oxide catalyst in soot oxidation

Jakubek

Kaspera

Legutko

et al. 2015

Catalysis Communications

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“…Most publications state that alkali metal salts are among the most effective salts with regard to their catalytic properties as well as their cost‐effectiveness, and K salts were favored frequently . This also applies to K compounds as promoters for oxidic catalysts . As stated above, the mechanistic role of K is not yet clear, and a tremendous number of postulated mechanisms can be found in the literature.…”

Section: Introductionmentioning

confidence: 99%

“…The various alkali metal salts can also be classified according to their reactivity. Generally, the reactivity increases throughout the group of alkali metals, and Rb has a comparable activity to K. There are also publications on certain types of coal were the order of the alkali metals was the other way around or there was no specific order . The order of reactivity of K salts with regard to the anions decreases generally from K 2 CO 3 /KOH>KHCO 3 >KNO 3 >K 2 SO 4 ≈KCl, and KCl is the least reactive with almost no activity because of the formation of too‐stable salts .…”

Section: Introductionmentioning

confidence: 99%

Catalytic Effect of Potassium Compounds in Soot Oxidation

2017

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The combustion temperatures of soot in particulate filters can be decreased to exhaust gas temperatures by using catalysts. In addition to oxidic catalysts, alkali metal salts are very effective catalysts. Although soot is one of the world's most unwanted byproducts, combustion is still not fully understood. In this study, different soot mixed internally with salt samples were produced. All salts lead to a marked, salt‐ and salt‐content‐dependent decrease of the temperature‐programmed oxidation temperatures of maximum CO + CO2 emissions (Tmax), with K2CO3 being one of the most effective catalysts that leads to a decrease of the Tmax of up to 300 °C. Structural parameters of the internally mixed soot derived by using Raman microspectroscopy, SEM, and scanning mobility particle size analysis did not change significantly; BET areas showed slight trends to lower areas with increased salt content, but no substantial correlations were observed. In contrast, a correlation of the oxidation reactivity to the number distribution of the measured actual fringe lengths by using high‐resolution transmission electron microscopy and the peak areas measured by using EPR spectroscopy was found. Salts lead to a narrowing of the actual fringe length number distributions to lower sizes and to reduced EPR peak areas. This demonstrates that the salts influence the nanostructure of the graphene planes by shortening the planes and further substantiates that soot oxidation is at least partly based on electron transfer and not only oxygen transfer. EPR spectroscopy measurements indicate that the oxidation mechanism is based on a temperature‐dependent chemical equilibrium, which depends on the K+/anion binding strength.

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“…Enhancing the catalytic activity of such materials by alkali addition has been frequently reported [20][21][22][23][24]. Doping occurs mainly in one of two ways: alkali cations can be dispersed on the surface [25,26] or intercalated into the structure [20].…”

Section: Introductionmentioning

confidence: 99%

How to Efficiently Promote Transition Metal Oxides by Alkali Towards Catalytic Soot Oxidation

et al. 2016

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The effect of surface and bulk potassium promotion on the transition metal oxides (Mn, Fe, Co) catalytic activity in catalytic soot oxidation was investigated. The surface promotion was obtained via incipient wetness impregnation, whereas the bulk promotion-nanostructuration-was obtained via wet chemical synthesis or solid state reaction leading to mixed oxide materials. The introduction of potassium into the transition metal oxide matrix results in the formation of tunneled or layered structures, which enable high potassium mobility. The structure of the obtained materials was verified by powder X-ray diffraction and Raman spectroscopy and the catalytic activity in soot oxidation was determined by TPO-QMS and TGA. It was found that the surface promotion does not alter the metal oxide structure and leads to either enhancement (Mn, Fe) or deterioration (Co) of the catalytic activity. Simultaneously, the catalytic activity in soot combustion of the potassium structured oxides is strongly enhanced. The most active, cobalt oxide based catalyst significantly lowers the temperature of 50 % of soot conversion by *350°C comparing to the non-catalyzed process. The study allows for the establishment of rational guidelines for designing robust materials for DPF applications based on ternary metal oxides.

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Carbonate‐Promoted Catalytic Activity of Potassium Cations for Soot Combustion by Gaseous Oxygen

Cited by 29 publications

References 73 publications

Surface versus bulk alkali promotion of cobalt-oxide catalyst in soot oxidation

Surface versus bulk alkali promotion of cobalt-oxide catalyst in soot oxidation

Catalytic Effect of Potassium Compounds in Soot Oxidation

How to Efficiently Promote Transition Metal Oxides by Alkali Towards Catalytic Soot Oxidation

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