Theoretical Study of Metal and Metal-oxide Catalysts by Molecular Orbital Method

分子轨道法金属和金属氧化物催化剂的理论研究

• 批准号: 09650865
• 负责人: KOBAYASHI Hisayoshi
• 金额: $ 1.98万
• 依托单位: Kurashiki University of Science and the Arts
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650865/
• 关键词: density functional method; catalysis; Epoxidation; Ag cluster; 電子構造; 結晶軌道法; 分子軌道法; 金属表面; 金属酸化物表面; 触媒作用

The mechanism of ethylene epoxidation on Ag surfaces has been investigated using the density functional method and Ag_n clusters (n=3 to 10) modeling the Ag(111) surface. Adsorption energy of 0_2 to the Ag clusters was strongly dependent on the HOMO level of the cluster, and the clusters with higher HOMO level afforded larger 0_2 adsorption energies. The energetics was investigated for both the molecular and atomic oxygen epoxidation mechanisms. For the atomic oxygen mechanism, the epoxidation was found to proceed ithout the activation energy, whereas a small amount of activation energy (ca 5 kcal/mol) was calculated for the molecular oxygen mechanism. Since the activation energy is not so large, this reaction seems to occur under usual reaction conditions above the room temperatures. Irrespective of the molecular oxygen mechanism, our calculation showed that the epoxidation could proceed through the atomic oxygen mechanism. The selectivity higher than 6/7 is possible if side reactions are supressed effectively.

采用密度泛函方法，以Ag_n团簇（n=3 ~ 10）模拟Ag（111）表面，研究了乙烯在Ag（111）表面上的环氧化反应机理. O_2在Ag团簇上的吸附能与团簇的HOMO能级密切相关，HOMO能级越高，吸附能越大。研究了分子氧和原子氧环氧化反应机理的能量学。对于原子氧机理，环氧化反应没有活化能，而少量的活化能（约5千卡/摩尔）计算的分子氧机制。由于活化能不是很大，该反应似乎在高于室温的通常反应条件下发生。不考虑分子氧机理，我们的计算表明环氧化反应可以通过原子氧机理进行。如果副反应得到有效抑制，选择性高于6/7是可能的。

项目成果

藤原、細川、村越、和田、柳田、岡田、小林: "Effect of surface structures on photpcatalytic CO_2 reduction using quantized" Jaurnal of Physical Chemistry B. 101/41. 8270-8278 (1997)

Fujiwara、Hosokawa、Murakoshi、Wada、Yanagita、Okada、Kobayashi：“表面结构对量子化光催化 CO_2 还原的影响”物理化学杂志 B. 8270-8278 (1997)。

Kobayashi,Nakashiro and Iwakura: "Density Functional Study of Ethylence Oxidation on Ag(111) Surface" Theoretical Chemistry Accounts. (in press). (1999)

Kobayashi、Nakashiro 和 Iwakura：“Ag(111) 表面乙烯氧化的密度泛函研究”理论化学说明。

小林・大久保: "Devsity functional study of NO^x reducation in zeolitecage" Applied Surface Science. 121/122. 111-115 (1997)

Kobayashi 和 Okubo：“沸石笼中 NO^x 还原的 Devsity 功能研究”应用表面科学 111-115（1997）。

Kobayashi, Nakashiro, and Iwakura: "Density Functional Study of Ethylene Oxidation on Ag(III)Surfare" Theoretical Chemistry Accounts. in press. (1999)

Kobayashi、Nakashiro 和 Iwakura：“Ag(III) 表面乙烯氧化的密度泛函研究”理论化学说明。

Kobayashi, Nakashiro and Iwakura: "Density Functional Study of Ethylene Oxidation on Ag (111) surface" Theoretical Chemistry Accounts. (in press). (1999)

Kobayashi、Nakashiro 和 Iwakura：“Ag (111) 表面乙烯氧化的密度泛函研究”理论化学说明。