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 (SAE)

  400 Commonwealth Drive
  Warrendale, PA  United States  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

• TRT Terms: Calcium; Catalysts; Exhaust gases; Metals; Purification; Soil stabilization; Temperature
• Old TRIS Terms: Calcium /soil stabilizer/; Deactivation
• Subject Areas: Geotechnology; Highways; Maintenance and Preservation; Safety and Human Factors;

Filing Info

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