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Characterization of a Pt-Pd combustion catalyst on an alumina washcoat, with and without prior hydrothermal treatment of the washcoat

Magnus Skoglundh (Institutionen för teknisk kemi) ; Lars Löwendahl (Institutionen för teknisk kemi) ; Govind Menon (Institutionen för teknisk kemi) ; Bertil Stenbom (Institutionen för fysik) ; Jean-Paul Jacobs ; Otto van Kessel ; Hidde Brongersma
Catalysis Letters (1011-372X). Vol. 13 (1992), 1-2, p. 27-38.
[Artikel, refereegranskad vetenskaplig]

Two Pt/Pd catalysts on cordierite monoliths were prepared by impregnating two differently treated alumina washcoats with 10/micromol [Pt + Pd] per gram catalyst in the atomic ratio Pt/Pd = 4.0. Both washcoats were first thermally treated, calcined, for 2 h at 550C in air and one of them was additionally treated, hydrothermally, in 100% steam for 2 h at 814C. The hydrothermally treated catalyst was more active for complete oxidation of xylene in air: its light-off temperature was 232C compared to 259C for the sample calcined only. To explain this higher activity, both catalysts were characterized by BET surface area, pore-size distribution, hydrogen chemisorption, X-ray diffraction, TEM/STEM/EDS and low-energy ion scattering spectroscopy (LEIS). The catalyst with a hydrothermally treated washcoat had 30% lower surface area, larger alumina crystal size, higher degree of crystallization of alumina and larger average catalyst pore size (11 nm vs. 6 nm), than the one with the washcoat, treated only thermally. The LEIS results indicated a surface enrichment of Pd on both catalysts. The Pt signal in LEIS was higher for the hydrothermally treated sample.

Nyckelord: Pt-Pd/alumina; combustion catalyst; hydrothermal treatment; xylene oxidation; light-off temperature; TEM/STEM/EDS; LEIS

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Denna post skapades 2012-02-06. Senast ändrad 2017-09-14.
CPL Pubid: 154794


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