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Accelerated deactivation studies of the natural-gas oxidation catalyst-Verifying the role of sulfur and elevated temperature in catalyst aging

M. Honkanen ; M. Karkkainen ; T. Kolli ; O. Heikkinen ; V. Viitanen ; Lunjie Zeng (Institutionen för fysik, Eva Olsson Group (Chalmers)) ; H. Jiang ; K. Kallinen ; M. Huuhtanen ; R. L. Keiski ; J. Lahtinen ; Eva Olsson (Institutionen för fysik, Eva Olsson Group (Chalmers)) ; M. Vippola
Applied Catalysis B: Environmental (0926-3373). Vol. 182 (2016), p. 439-448.
[Artikel, refereegranskad vetenskaplig]

Accelerated deactivation, caused by thermal aging (TA) and/or sulfur + water poisoning (SW), of the PtPd/gamma-Al2O3 natural-gas oxidation catalyst was studied. Thermal aging and poisoning treatments were performed separately and with varied combinations and comprehensive characterization of the catalyst was carried out after each step. The fresh catalyst has small, oxidized PtPd particles (<5 nm) uniformly distributed in the gamma-alumina washcoat. After the SW-treatment, a small amount of bulk aluminum sulfate was observed near the slightly grown noble metal particles. During the thermal aging, gamma-alumina changed to delta-/theta- and alpha-alumina. In addition, total decomposition of oxidized Pt and partly decomposition of oxidized Pd occurred resulting in the formation of the grown noble metal particles with a bimetallic PtPd core and a polycrystalline PdO shell. Also few, small (similar to 5 nm) bimetallic PtPd particles were still detected. In the TA + SW-treated catalyst with grown noble metal particles, a small amount of bulk aluminum sulfate was detected and it was randomly distributed over the noble metal particles and washcoat. The activity in the terms of methane conversion over the TA-, SW-, and SW + TA-treated catalysts was similar but it was decreased compared to the fresh catalyst. The activity of the TA+SW-treated catalyst was drastically decreased compared to the fresh catalyst due to significant morphological changes and aluminum sulfate formation.

Nyckelord: Palladium, Platinum, Deactivation, Thermal aging, Sulfur poisoning



Denna post skapades 2016-01-07. Senast ändrad 2016-01-29.
CPL Pubid: 229953

 

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Institutioner (Chalmers)

Institutionen för fysik, Eva Olsson Group (Chalmers)

Ämnesområden

Teknisk fysik

Chalmers infrastruktur

 


Projekt

Denna publikation är ett resultat av följande projekt:


Enabling Science and Technology through European Electron Microscopy (ESTEEM 2) (EC/FP7/312483)