Accelerated deactivation studies of the natural-gas oxidation catalyst-Verifying the role of sulfur and elevated temperature in catalyst aging
Journal article, 2016

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.

Thermal aging

Sulfur poisoning





M. Honkanen

Tampere University of Technology

M. Karkkainen

University of Oulu

T. Kolli

University of Oulu

O. Heikkinen

Aalto University

V. Viitanen

Aalto University

Lunjie Zeng

Chalmers, Physics, Eva Olsson Group

H. Jiang

Aalto University

Kauko Kallinen

Ecocat Oy

M. Huuhtanen

University of Oulu

R. L. Keiski

University of Oulu

J. Lahtinen

Aalto University

Eva Olsson

Chalmers, Physics, Eva Olsson Group

M. Vippola

Tampere University of Technology

Applied Catalysis B: Environmental

0926-3373 (ISSN) 1873-3883 (eISSN)

Vol. 182 439-448

Enabling Science and Technology through European Electron Microscopy (ESTEEM 2)

European Commission (FP7), 2012-10-01 -- 2016-09-30.

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Other Engineering and Technologies



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