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| 2. |
- Arnby, Karl, 1974, et al.
(författare)
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Characterization of Pt/γ-Al2O3 catalysts deactivated by hexamethyldisiloxane
- 2004
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Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 54:1, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- The deactivation of alumina supported platinum and iron catalysts by hexamethyldisiloxane (HMDS) exposure has been investigated. Three catalysts (Pt/Al2O3, Fe/Al2O3 and Fe/Pt/Al2O3) were prepared and the influence of short- and long-term deactivation on the activity for oxidation of ethyl acetate was studied. The catalysts were characterized using BET, ICP-AES, XPS, SEM and CO chemisorption. The deactivation was found to proceed by deposition of silicon-species in form of silicate (SixOy) that block the active sites on the surface of the catalysts. The silicon seems to rather attach to platinum and iron sites than to the alumina surface. The Pt/Al2O3 catalyst was moderately deactivated by HMDS even though the silicate was blocking almost the entire platinum surface. Adding iron to the catalyst increased the tolerance towards HMDS as fewer Pt sites were blocked for the Fe/Pt/Al2O3 sample. The deactivation of the two platinum containing samples was reversible since the silicate could partly be removed from the Pt sites by regeneration whereby most of the activity was restored. However, for the Fe/Al2O3 sample the deactivation was more severe and irreversible.
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| 3. |
- Augustsson, Ola
(creator_code:cre_t)
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A catalyst for catalytic oxidation of hydrocarbons
- 2004
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Patent (övrigt vetenskapligt/konstnärligt)abstract
- A catalyst having resistance towards Si and/or P deactivation in catalytic oxidation of organic hydrocarbons is disclosed. The catalyst comprises a catalytically inert support, a catalytically active layer of metallic Pt and/or Pd and deposited on said catalytically active layer at least one oxide ...
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| 8. |
- Larsson, Ann-Charlotte, et al.
(författare)
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Pilot-scale investigation of Pt/alumina catalysts deactivation by organosilicon in the total oxidation of hydrocarbons
- 2007
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Ingår i: Topics in Catalysis. - : Springer Science and Business Media LLC. - 1572-9028 .- 1022-5528. ; 45:1-4, s. 121-124
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Tidskriftsartikel (refereegranskat)abstract
- The deactivation of alumina-supported platinum catalyst for VOC oxidation by long-term exposure for hexamethyldisiloxane (HMDS) has been investigated in a pilot scale reactor for up to 1000 h of exposure. Catalyst samples were characterized by ICP-AES, BET and silicon deposition by SEM. Catalyst activity was investigated using oxidation of ethyl acetate showing deactivation of the catalyst samples as exposed to HMDS increasing with exposure time. Silicon was shown to deposit on the catalyst as well as on the blank alumina support. SEM investigation of an individual pellet revealed a radial eggshell silicon distribution. CO chemisorption showed strong decrease of Pt active sites after deactivation, while still maintaining reasonable oxidation levels of ethyl acetate.
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| 10. |
- Petersson, Martin, 1972, et al.
(författare)
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Ozone promoted carbon monoxide oxidation on platinum/gamma-alumina catalyst
- 2006
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Ingår i: Journal of Catalysis. - : Elsevier BV. - 0021-9517 .- 1090-2694. ; 238:2, s. 321-329
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Tidskriftsartikel (refereegranskat)abstract
- CO oxidation with oxygen and ozone-oxygen mixtures was studied over a platinum/alumina monolith catalyst. Temperature ramp experiments were combined with mean-field Simulations to Study the reaction mechanisms. In the absence of ozone, a slow CO oxidation reaction was observed at low temperatures. The rate of this slow reaction was proportional to the square root of the oxygen pressure and independent of the CO concentration. At higher temperatures, the three-step Langmuir-Hinshelwood reaction mechanism dominated the CO oxidations. When some of the oxygen was exchanged for ozone, rapid oxidation of CO by ozone was observed. The suggested explanation was an Eley-Rideal mechanism, in which colliding ozone reacts with adsorbed CO oil the platinum surface. When this additional reaction step was included in the model, the Simulation results indicated a reduction in the bulk CO pressure. The experimentally observed ozone promotion of CO oxidation was thus attributed to a decrease in CO Surface self-poisoning.
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