Promoted Pt catalysts for automotive pollution control: Characterization of Pt/SiO{sub 2}, Pt/CoO{sub x}/SiO{sub 2}, and Pt/MnO{sub x}/SiO{sub 2} catalysts

Journal Article · Sat Jun 01 04:00:00 EDT 1996 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1996.0189· OSTI ID:471628

Mergler, Y J; Aalst, A van; Delft, J van; Nieuwenhuys, B E ^[1]

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1. Leiden Univ. (Netherlands)

The characterization of Pt/SiO{sub 2}, Pt/CoO{sub x}/SiO{sub 2}, Pt/MnO{sub x}/SiO{sub 2}, CoO{sub x}/SiO{sub 2}, and MnO{sub x}/SiO{sub 2} catalysts with 5 wt% Pt, 25 wt% MnO{sub 2}, 50 wt% Co{sub 3}O{sub 4}, and 3 wt% Co{sub 3}O{sub 4} is described. The pt/CoO{sub x}/SiO{sub 2} catalyst is particularly active in low-temperature CO oxidation, while the Pt/MnO{sub x}/SiO{sub 2} catalyst is more active in NO reduction by CO than the unpromoted Pt catalyst. The characterization techniques used are (1) X-ray diffraction, to determine the average particle size and possible alloy formation; (2) CO chemisorption, to determine the specific Pt surface area; and (3) Fourier transform infrared spectroscopy, to study the adsorption of CO and NO and the interaction between CO and NO. The influence of a reductive or oxidative pretreatment is also examined. After a reductive pretreatment the high-loaded Pt/50CoO{sub x}/SiO{sub 2} catalyst shows the formation of a PtCo alloy and Co{sup 0} metal. No alloy formation was detected for the Pt/3CoO{sub x}/SiO{sub 2} catalyst. Fourier transform infrared measurements show the characteristic bands of linearly adsorbed CO on Pt at 2070 cm{sup {minus}1}, and linear and bent NO on cobalt oxide at 1870 and 1790 cm{sup {minus}1}, respectively. For the high-loaded Pt/50CoO{sub x}/SiO{sub 2} a shoulder at 2023 cm{sup {minus}1} is observed and ascribed to CO linearly bound to cobalt metal. An isocyanate band at 2200 cm{sup {minus}1} is found for the Pt/3CoO{sub x}/SiO{sub 2}, Pt/50CoO{sub x}/SiO{sub 2}, Pt/MnO{sub x}/SiO{sub 2}, and MnO{sub x}/SiO{sub 2} catalysts on coadsorption of CO and NO. 34 refs., 8 figs., 2 tabs.

• OSTI ID: 471628
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 161; ISSN JCTLA5; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
40 CHEMISTRY
ABSORPTION SPECTROSCOPY
CARBON MONOXIDE
CATALYST SUPPORTS
CHEMISORPTION
COBALT OXIDES
HETEROGENEOUS CATALYSIS
MANGANESE OXIDES
PLATINUM
SILICA
SORPTIVE PROPERTIES
STRUCTURAL CHEMICAL ANALYSIS
X-RAY DIFFRACTION