MODES OF DEACTIVATION OF EXHAUST PURIFICATION CATALYSTS

Crushed samples of Engelhard PTX (II-B) catalyst were calcined at temperatures between 900-2700 degrees F. When the temperature exceeds about 100 degrees F in air, the crystallites of precious metals (platinum-palladium) grow larger, exposing less surface for catalysis. When the catalyst is exposed to temperatures on the order of 1500-1800 degrees F for extended periods of time (16 h or more), the wash-coat tends to lose a substantial precentage of its surface area. Finally, above about 2300 degrees F, the cordierite of the ceramic becomes converted to mullite and amorphous material. Catalysts examined after 8000-20,000 equivalent miles of steady-state (70 mph) on a stationary engine with catalyst temperatures at 1350-1500 degrees F show results consistent with those obtained from our calcination studies. Pore volume distribution data after artificial or real deactivation conditions were used to obtain diffusion coefficients for use in a published model. /GMRL/

  • Corporate Authors:

    Society of Automotive Engineers

    400 Commonwealth Drive
    Warrendale, PA  USA  15096
  • Authors:
    • Johnson, MFL
    • Mooi, J
    • Erickson, H
    • Kreger, W E
    • Breder, E W
  • Publication Date: 1974-10

Media Info

  • Pagination: 14 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00096090
  • Record Type: Publication
  • Report/Paper Numbers: SAE Paper No 741079
  • Files: TRIS
  • Created Date: Aug 13 1975 12:00AM