Release of nanoparticles in the environment and catalytic converters ageing

Sofía Navarro-Espinoza, Diana Meza-Figueroa*, Roberto Guzmán, Alberto Duarte-Moller, Hilda Esparza-Ponce, Francisco Paz-Moreno, Belem González-Grijalva, Osiris Álvarez-Bajo, Benedetto Schiavo, Diego Soto-Puebla, Martín Pedroza-Montero*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


A Three-Way Catalyst (TWC) contains a cordierite ceramic monolith coated with a layer of Al2 O3, Cex Zr1−x O2 and platinoids mixture. Under standard operation, the platinoid concentration decreases, exposing the remaining washcoat structure. After that particle release stage, the sintering process follows where the crystalline Cex Zr1−x O2 solution is broken and begins to separate into ZrO2 and CeO2 phases. ZrO2 is released to the environment as micro and nanoparticles, while a small amount of CeO2 generates a new Alx Ce1−x O2 composite. The main effect of Ce capture is the growth in the size of the polycrystal structure from 86.13 ± 16.58 nm to 225.35 ± 69.51 nm. Moreover, a transformation of cordierite to mullite was identified by XRD analysis. Raman spectra showed that the oxygen vacancies (Vö) concentration decreased as Cex Zr1−x O2 phases separation occurred. The SEM-EDS revealed the incorporation of new spurious elements and microfractures favouring the detachment of the TWC support structure. The release of ultrafine particles is a consequence of catalytic devices overusing. The emission of refractory micro to nanocrystals to the atmosphere may represent an emerging public health issue underlining the importance of implementing strict worldwide regulations on regular TWCs replacement.

Original languageEnglish
Article number3406
Issue number12
StatePublished - Dec 2021

Bibliographical note

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© 2021 by the authors. Licensee MDPI, Basel, Switzerland.


  • Non-exhaust emissions
  • Refractory nanoparticles
  • Sintering nanoparticles
  • Vehicle catalyst
  • Washcoat loss


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