Kinetic and mechanistic study of bimetallic Pt-Pd/Al₂O₃ catalysts for CO and C₃H₆ oxidation

Journal Article · Wed Sep 21 04:00:00 EDT 2016 · Applied Catalysis. B, Environmental

DOI:https://doi.org/10.1016/j.apcatb.2016.09.034· OSTI ID:1330523

Hazlett, Melanie J. ^[1]; Moses-Debusk, Melanie ^[2]; Parks, III, James E. ^[2]; Allard, Jr., Lawrence Frederick ^[2]; Epling, William S. ^[1]

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1. Univ. of Houston, Houston, TX (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Low temperature combustion (LTC) diesel engines are being developed to meet increased fuel economy demands. However, some LTC engines emit higher levels of CO and hydrocarbons and therefore diesel oxidation catalyst (DOC) efficiency will be critical. Here, CO and propylene oxidation were studied, as representative LTC exhaust components, over model bimetallic Pt-Pd/γ-Al₂O₃ catalysts. During CO oxidation tests, monometallic Pt suffered the most extensive inhibition which was correlated to a greater extent of dicarbonyl species formation. Pd and Pd-rich bimetallics were inhibited by carbonate formation at higher temperatures. The 1:1 and 3:1 Pt:Pd bimetallic catalysts did not form the dicarbonyl species to the same extent as the monometallic Pt sample, and therefore did not suffer from the same level of inhibition. Similarly they also did not form carbonates to as large an extent as the Pd-rich samples and were therefore not as inhibited from this intermediate surface species at higher temperature. The Pd-rich samples were relatively poor propylene oxidation catalysts; and partial oxidation product accumulation deactivated these catalysts. Byproducts observed include acetone, ethylene, acetaldehyde, acetic acid, formaldehyde and CO. For CO and propylene co-oxidation, the onset of propylene oxidation was not observed until complete CO oxidation was achieved, and the bimetallics showed higher activity. In conclusion, this was again related to less extensive poisoning, less dicarbonyl species formation and less overall partial oxidation product accumulation.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: ORNL work for others; USDOE
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1330523
• Journal Information: Applied Catalysis. B, Environmental, Journal Name: Applied Catalysis. B, Environmental Journal Issue: C Vol. 202; ISSN 0926-3373
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CO oxidation
bimetallic Pt:Pd catalysts
oxidation catalyst
propylene oxidation