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Application of Resonance Oscillation to the Design of Heterogeneous Catalysts with Artificially Controllable Functions for Chemical Reactions

共振振荡在化学反应人工可控功能多相催化剂设计中的应用

基本信息

批准号：
15206088
负责人：
INOUE Yasunobu
金额：
$ 29.62万
依托单位：
Nagaoka University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

项目摘要

Resonance oscillation (RO) of bulk acoustic waves generated by piezoelectric effects on poled ferroelectric crystals by rf electric power causes the dynamic distortion of thin metal film surfaces deposited. In C_2H_5OH and CO oxidation and C_2H_5OH decomposition on Ag and Pd catalysts, thickness-extension mode RO (TERO) was found to have a capability of enhancing not only catalytic activity, but also reaction selectivity. In contrast, thickness-shear mode resonance oscillation (TSRO) showed no activation effects. Laser Doppler and photoemission spectroscopic measurements showed that TERO caused large lattice displacement vertical to the surface and to induce work function shifts of the metal catalysts, whereas no such changes occurred with TSRO. The TERO effects on catalyst activation depended on the polarization direction of ferroelectric substrates and resonance frequency, indicating that large vertical lattice displacement and the density of sites causing lattice displacement are responsible for strong catalyst activation. The TERO effects were intrinsically different in ethanol decomposition between Ag and AgAu alloy catalysts. TERO-induced activation occurred only for ethylene production on a Ag metal, whereas TERO effects had strong dependence on alloy compositions. The activation for ethylene production was nearly independent of alloy composition, but that for acetaldehyde production exhibited a maximum at around 80% surface Au content where the vertical lattice displacement became the smallest. Thus, it was proposed that the TERO effects on acetaldehyde production over the AgAu binary alloy catalysts increased in the case where Ag-Au atom interactions became strong. The RO effects on heterogeneous catalysis by metals are new phenomena and are concluded to be quite useful for the development of a heterogeneous catalyst with artificially controllable functions for chemical reactions.

在射频电源作用下，极化铁电晶体的压电效应产生的体声波的共振振荡（RO）会引起沉积金属薄膜表面的动态畸变。在Ag和Pd催化剂上C_2H_5OH和CO氧化及C_2H_5OH分解反应中，发现厚度延伸型RO（TERO）不仅能提高催化活性，而且能提高反应选择性。相反，厚度剪切模式共振振荡（TSRO）显示没有激活效果。激光多普勒和光电子能谱测量结果表明，TERO引起大的晶格位移垂直于表面，并诱导功函数移动的金属催化剂，而没有发生这样的变化与TSRO。TERO对催化剂活化的影响取决于铁电衬底的极化方向和共振频率，表明大的垂直晶格位移和引起晶格位移的位置密度是催化剂强活化的原因。Ag和AgAu合金催化剂在乙醇分解过程中的TERO效应有本质的不同。TERO诱导的激活只发生在Ag金属上的乙烯生产，而TERO效应对合金成分有很强的依赖性。乙烯生产的激活几乎是独立的合金组成，但乙醛生产表现出最大的表面Au含量约80%的垂直晶格位移成为最小的。因此，有人提出，在Ag-Au原子相互作用变得强的情况下，在AgAu二元合金催化剂上乙醛生成的TERO效应增加。反渗透效应对金属多相催化是一种新的现象，并得出结论，是非常有用的多相催化剂的发展与人工可控功能的化学反应。