Investigation of the degradation mechanism of catalytic wires during oxidation of ammonia process

Jarosław Pura , Piotr Wieciński , Piotr Kwaśniak , Marta Zwolińska , Halina Garbacz , Joanna Zdunek , Zbigniew Laskowski , Maciej Gierej


The most common catalysts for the ammonia oxidation process are 80 μm diameter platinum-rhodium wires knitted or woven into the form of a gauze. In an aggressive environment and under extreme conditions (temperature 800–900 °C, intensive gas flow, high pressure) precious elements are drained from the surface of the wires. Part of this separated material quickly decomposes on the surface in the form of characteristic “cauliflower-shape protrusions”. The rest of the platinum is captured by palladium-nickel catalytic-capture gauzes located beneath. In our investigation we focused on the effects of the degradation of gauzes from one industrial catalytic system. The aim of the study was to compare the degree and the mechanism of degradation of gauzes from a different part of the reactor. The study covered PtRh7 catalytic and PdNi5 catalytic-capture gauzes. X-ray computer microtomography investigation revealed that despite strong differences in morphology, each Pt-Rh wire has a similar specific surface area. This indicates that the oxidation process and morphological changes of the wires occur in a self-regulating balance, resulting in the value of the specific surface area of the catalyst. Microtomography analysis of Pd-Ni wires revealed strong redevelopment of the wires’ surface, which is related to the platinum capture phenomenon. Scanning electron microscope observations also revealed the nanostructure in the cauliflower-shape protrusions and large grains in the wires’ preserved cores. The high temperature in the reactor and the long-term nature of the process do not favor the occurrence of the nanostructure in this type of material. Further and detailed analysis of this phenomena will provide a better understanding of the precious metals etching and deposition processes during oxidation.
Author Jarosław Pura (FMSE / DMD)
Jarosław Pura,,
- Division of Materials Design
, Piotr Wieciński (FMSE / DMD)
Piotr Wieciński,,
- Division of Materials Design
, Piotr Kwaśniak (FMSE / DMD)
Piotr Kwaśniak,,
- Division of Materials Design
, Marta Zwolińska (FMSE / DMD)
Marta Zwolińska,,
- Division of Materials Design
, Halina Garbacz (FMSE / DMD)
Halina Garbacz,,
- Division of Materials Design
, Joanna Zdunek (FMSE / DMD)
Joanna Zdunek,,
- Division of Materials Design
, Zbigniew Laskowski - Menica Metale Szlachetne S.A. [Precious Metal Mint]
Zbigniew Laskowski,,
, Maciej Gierej - Mennica Metale Szlachetne S.A. [Precious Metal Mint]
Maciej Gierej,,
Journal seriesApplied Surface Science, ISSN 0169-4332
Issue year2016
Publication size in sheets0.5
Keywords in EnglishCatalysis; Degradation; Platinum
ASJC Classification2508 Surfaces, Coatings and Films
Languageen angielski
JP_Investigation of the degradation mechanism of catalytic wires during oxidation.pdf 3.7 MB
Score (nominal)35
Score sourcejournalList
ScoreMinisterial score = 35.0, 10-06-2020, ArticleFromJournal
Ministerial score (2013-2016) = 35.0, 10-06-2020, ArticleFromJournal
Publication indicators Scopus Citations = 1; WoS Citations = 0; Scopus SNIP (Source Normalised Impact per Paper): 2016 = 1.209; WoS Impact Factor: 2016 = 3.387 (2) - 2016=3.184 (5)
Citation count*
Share Share

Get link to the record

* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.
Are you sure?