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Catalytic combustion of methane in steam and carbon dioxide-diluted reaction mixtures
KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
2006 (engelsk)Inngår i: Applied Catalysis, ISSN 0166-9834, E-ISSN 1873-3867, Vol. 312, s. 95-101Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Supported palladium catalysts have been tested for methane combustion under lean conditions in the temperature range of 200-800 degrees C. The effect of diluting the reaction mixture with high amounts of water and carbon dioxide was studied in order to simulate a combustion process with exhaust gas recirculation. The influence of support material, i.e. ZrO2 or doped CeO2, on the catalytic performance was also investigated.

The catalyst support material was found to influence the light-off temperature significantly, which increased in the following order: Pd/ZrO2 < Pd/Zr-CeO2 < Pd/La-CeO2. The order of activity changed at higher temperatures resulting in Pd/La-CeO2 being the most active catalyst above 670 degrees C. This catalyst also shows a more stable performance with no distinct deactivation occurring at higher temperatures during cooling.

Both water and CO2 were found to have a negative influence on the catalytic activity. The inhibitory effect was, however, more pronounced for water. This inhibitory effect was present in the entire temperature range investigated. Adding CO2 in the presence of water resulted in conversions similar to the ones observed when feeding water alone for Pd/ZrO2 and Pd/La-CeO2, On the contrary, the activity of Pd/Zr-CeO2 was further decreased when co-feeding water and CO2.

sted, utgiver, år, opplag, sider
2006. Vol. 312, s. 95-101
Emneord [en]
catalytic combustion, palladium, TPO, AZEP, water inhibition, CO2 inhibition
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-6638DOI: 10.1016/j.apcata.2006.06.032ISI: 000240639000012Scopus ID: 2-s2.0-33747828180OAI: oai:DiVA.org:kth-6638DiVA, id: diva2:11402
Merknad
QC 20101126Tilgjengelig fra: 2006-12-15 Laget: 2006-12-15 Sist oppdatert: 2020-03-05bibliografisk kontrollert
Inngår i avhandling
1. Development of catalysts for natural gas-fired gas turbine combustors
Åpne denne publikasjonen i ny fane eller vindu >>Development of catalysts for natural gas-fired gas turbine combustors
2006 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Due to continuously stricter regulations regarding emissions from power generation processes, further development of existing gas turbine combustors is essential. A promising alternative to conventional flame combustion in gas turbines is catalytic combustion, which can result in ultralow emission levels of NOx, CO and unburned hydrocarbons. The work presented in this thesis concerns the development of methane oxidation catalysts for gas turbine combustors. The application of catalytic combustion to different combustor concepts is addressed in particular.

The first part of the thesis (Paper I) reports on catalyst development for fuel-lean methane combustion. Supported Pd-based catalysts were investigated at atmospheric pressure. The effect on catalytic activity of diluting the reaction mixture with water and/or carbon dioxide was studied in order to simulate a combustion process with exhaust gas recirculation. The catalytic activity was found to decrease significantly in the presence of water and CO2. However, modifying the catalyst by changing support material can have a considerable impact on the performance.

In the second part of this thesis (Papers II-IV), the development of rhodium catalysts for fuel-rich methane combustion is addressed. The effect of catalyst composition, oxygen-to-fuel ratio and catalyst pre-treatment on the methane conversion and the product gas composition was studied. An experimental investigation at elevated pressures of partial oxidation of methane/oxygen mixtures in exhaust gas-rich environments was also conducted. The most suitable catalyst identified for fuel-rich catalytic combustion of methane, i.e. Rh/Ce-ZrO2, showed benefits such as low light-off temperature, high activity and enhanced hydrogen selectivity.

In the final part of the thesis (Paper V), a numerical investigation of fuel-rich catalytic combustion is presented. Measurements and predictions were compared for partial oxidation of methane in exhaust gas diluted mixtures at elevated pressures. The numerical model was validated for several Rh-based catalysts. The key parameter controlling the catalytic performance was found to be the noble metal dispersion.

sted, utgiver, år, opplag, sider
Stockholm: KTH, 2006. s. 67
Serie
Trita-KET, ISSN 1104-3466 ; R232
Emneord
AZEP, catalytic combustion, CPO, methane oxidation, palladium, rhodium, support effect
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-4239 (URN)91-7178-543-4 (ISBN)978-91-7178-543-5 (ISBN)
Disputas
2006-12-19, D2, D, Lindstedtsvägen 5, Stockholm, 10:00
Opponent
Veileder
Merknad
QC 20110125Tilgjengelig fra: 2006-12-15 Laget: 2006-12-15 Sist oppdatert: 2011-01-25bibliografisk kontrollert
2. Development of methane oxidation catalysts for different gas turbine combustor concepts
Åpne denne publikasjonen i ny fane eller vindu >>Development of methane oxidation catalysts for different gas turbine combustor concepts
2005 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Due to continuously stricter regulations regarding emissions from power generation processes, development of existing gas turbine combustors is essential. A promising alternative to conventional flame combustion in gas turbines is catalytic combustion, which can result in ultra low emission levels of NOx, CO and unburned hydrocarbons. The work presented in this thesis concerns the development of methane oxidation catalysts for gas turbine combustors. The application of catalytic combustion to different combustor concepts is addressed in particular.

The first part of the thesis (Paper I) reports on catalyst development for fuel-lean methane combustion. The effect on catalytic activity of diluting the reaction mixture with water and carbon dioxide was studied in order to simulate a combustion process with exhaust gas recirculation. Palladium-based catalysts were found to exhibit the highest activity for methane oxidation under fuel-lean conditions. However, the catalytic activity was significantly decreased by adding water and CO2, resulting in unacceptably high ignition temperatures of the fuel.

In the second part of this thesis (Paper II), the development of rhodium catalysts for fuel-rich methane combustion is addressed. The effect of water addition on the methane conversion and the product gas composition was studied. A significant influence of the support material and Rh loading on the catalytic behavior was found. The addition of water influenced both the low-temperature activity and the product gas composition.

sted, utgiver, år, opplag, sider
Stockholm: KTH, 2005. s. 35
Serie
Trita-KET, ISSN 1104-3466 ; 211
Emneord
Chemical engineering, catalytic combustion, methane oxidation, ceria, palladium, platinum, rhodium, TPO, Kemiteknik
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-311 (URN)
Presentation
2005-04-15, Teknikringen 42, Stockholm, 10:00
Veileder
Merknad
QC 20101126Tilgjengelig fra: 2005-07-18 Laget: 2005-07-18 Sist oppdatert: 2010-11-26bibliografisk kontrollert

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