Soot combustion with K/MgO as catalyst

Jiménez, Romel; Garcı́a, Ximena; Cellier, Caroline; Ruíz, Patricio; Gordon, Alfredo L.

doi:10.1016/j.apcata.2006.08.002

Cited by 51 publications

(45 citation statements)

References 17 publications

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“…The introduction of potassium on the MgO has an important catalytic effect, with decreases of over 200°C observed in the temperature values at the maximum combustion rate (T m ), both with About the active phases of KNO 3 /MgO for catalytic soot combustion 283 respect to the pure MgO and the uncatalyzed reaction. These results confirm what has been observed in previous works [6,10,11] and prove that only the phases associated with potassium should be considered as the main active phases in this type of catalyst for soot combustion.…”

Section: Resultssupporting

confidence: 94%

“…2 and 3, as proposed by Carrascull et al [7,13] and Sui et al [2]. The authors of the present paper have proven the high activity of K/MgO catalysts in the combustion of carbon black (CB), which has been used as a model compound for soot [6,11]. It was also shown that KNO 3 used as a precursor generated a slightly more active catalyst than KOH [6] when both were calcined at 760°C for 30 min.…”

Section: Introductionsupporting

confidence: 67%

“…2 indicates the presence of crystalline phases of potassium nitrates and carbonates in the fresh catalyst, as well as peaks associated with the potassium oxides (K x O y ), which could play an important role in the oxidation process, as suggested by Hüttinger and Minges [14]. The nitrates are related to the potassium precursor salt, which did not completely decompose during calcinations, whereas the carbonates were formed by the contact of the catalyst with the ambient CO 2 , which had already been observed in previous works [10,11]. On the other hand, the XRD pattern for the heated catalyst shows the absence of crystalline phases of potassium nitrate; only the crystalline phases of potassium oxides were observed in the sample, thus suggesting the decomposition of the potassium nitrate.…”

Section: Resultsmentioning

confidence: 66%

“…This is due to its low melting point that improves the sootcatalyst contact [2,7,11,13] as well as to the high oxidizing power that is attributed to the nitrate ion [2,7,13]. However, a disadvantage of this salt is that it tends to decompose above 500°C [7,18].…”

Section: Introductionmentioning

confidence: 98%

“…Potassium salts have been widely used for impregnation of different supports (MgO, CeO 2 , ZrO 2 ), forming highly active catalysts for soot combustion [1,[10][11][12][13]. The catalytic effect of different potassium salts has also been studied in processes of coal gasification with CO 2 and steam [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

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About the active phases of KNO3/MgO for catalytic soot combustion

Jiménez

Garcı́a

Gordon

2010

Reac Kinet Mech Cat

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Reports suggest KNO 3 as the active phase for the catalytic combustion of soot, through a redox mechanism with KNO 2 . Previously, the high activity of KNO 3 for coal gasification (mechanism similar to that of soot combustion) was attributed to decomposition into active K x O y (y \ x) compounds. In this work, TGA-MS assays of carbothermic reduction using the KNO 3 /MgO catalyst showed decomposition into NO x , (to which starting of CB combustion is attributed) and potassium oxide, thus disregarding possible redox cycles KNO 3 /KNO 2 . Consecutive assays of carbothermic reduction and TPO in a fixed bed reactor showed the potassium oxides as the main active phases of these catalysts.

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Section: Resultssupporting

confidence: 94%

Section: Introductionsupporting

confidence: 67%

Section: Resultsmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

About the active phases of KNO3/MgO for catalytic soot combustion

Jiménez

Garcı́a

Gordon

2010

Reac Kinet Mech Cat

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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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Modification of KNO₃ on the reducibility and reactivity of Fe₂O₃‐based oxygen carriers for chemical‐looping combustion of methane

Cheng

Wei

et al. 2017

Can J Chem Eng

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This work presented a comparative study on the Fe2O3‐based oxygen carriers modified by different potassium salts (i.e. KNO3, K3PO4, KOH, K2CO3) for chemical looping combustion of methane (CLC with methane). The effect of Al2O3 support on the reactivity of Fe2O3 was also investigated. The Fe2O3‐based oxygen carriers were prepared by a co‐precipitation method and the potassium salts were added via an incipient wetness impregnation method. The obtained oxygen carriers were characterized by XRD, XPS, H2‐TPR, and CH4‐TPR technologies. It was found that the presence of KNO3 could improve the reducibility of the Fe2O3‐based oxygen carrier in the surface, resulting in relatively high selectivity towards CO2 during the CLC with methane. The content of KNO3 also affected the reactivity of oxygen carriers, and 10 % KNO3/Fe2O3 sample showed the best activity. Moreover, it was also demonstrated that the addition of Al2O3 support into the 10 % KNO3/Fe2O3 oxygen carrier could improve its redox performance, and the stability of 10 % KNO3/Fe2O3/Al2O3 was proved to be favourable after twenty successive cycles for CLC with methane.

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Soot combustion with K/MgO as catalyst

Cited by 51 publications

References 17 publications

About the active phases of KNO3/MgO for catalytic soot combustion

About the active phases of KNO3/MgO for catalytic soot combustion

Catalytic Effect of Potassium Compounds in Soot Oxidation

Modification of KNO₃ on the reducibility and reactivity of Fe₂O₃‐based oxygen carriers for chemical‐looping combustion of methane

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Soot combustion with K/MgO as catalyst

Cited by 51 publications

References 17 publications

About the active phases of KNO3/MgO for catalytic soot combustion

About the active phases of KNO3/MgO for catalytic soot combustion

Catalytic Effect of Potassium Compounds in Soot Oxidation

Modification of KNO3 on the reducibility and reactivity of Fe2O3‐based oxygen carriers for chemical‐looping combustion of methane

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Modification of KNO₃ on the reducibility and reactivity of Fe₂O₃‐based oxygen carriers for chemical‐looping combustion of methane