Design of Catalysts with Artificially Controllable Functions Using Surface Acoustic Waves and Resonance Oscillations Generated on Ferroelectric Materials

Autor: Naruki Saito, Yuzuru Ohkawara, Y. Inoue, K. Sato
Rok vydání: 1997
Předmět:
Zdroj: MRS Proceedings. 497
ISSN: 1946-4274
0272-9172
DOI: 10.1557/proc-497-215
Popis: A poled ferroelectric material of a LiNbO3 single crystal and a polycrystalline lead strontium zirconium titanate(PSZT) disc were employed as a catalyst substrate, on which various metals such as Pd, Ag, Ni and Pt and a WO3 oxide were deposited as a thin film catalyst. The effects of acoustic waves generated by rf power upon catalyst activation and reaction selectivity have been examined. The activity for CO oxidation of a Pt/PSZT catalyst increased by a factor of 3.9 with a thickness-extensional(TE) mode of resonance oscillation(RO) and 2.9 with a radial-extensional (RE) mode. The activation energy of the reaction was larger for the TE mode( 38 kJmol−1) than that for the RE mode(24 kJmol−1). The polarization axis-dependent changes in surface potential occurred with the TE mode, but not with the RE mode. With the TE mode, the activation energy of ethanol oxidation over a Ni/LiNbO3 and a Ag/LiNbO3 catalyst decreased from 36 to 19 kJmol−1 and from 76 to 30 kJmol−1, respectively, and the TE mode had a larger effect on the reaction with a higher activation energy. In ethanol dehydrogenation and dehydration on a WO3 / LiNbO3 catalyst, the TE mode increased remarkably the selectivity for ethylene production without giving a significant change to acetaldehyde production. The effects of acoustic wave excitations on the catalysts are discussed.
Databáze: OpenAIRE
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