当前位置: X-MOL 学术Mol. Catal. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Ab initio studies of propene oxide formation at gold nanocatalysts supported on anatase-TiO2
Molecular Catalysis ( IF 4.6 ) Pub Date : 2020-03-05 , DOI: 10.1016/j.mcat.2020.110855
L.M. Molina , J.A. Alonso

Small gold particles supported on TiO2 are promising catalysts for the direct epoxidation of propene. Some experimental studies suggest a critical role of the oxide/gold interfacial region, where a bidentate propoxy species is formed during the reaction. However, it is not yet clear that such complex is a true reaction intermediate, and not a mere spectator or even a deactivating species. In order to clarify this issue, we have performed extensive ab initio simulations of the propene oxide formation on a model catalyst formed by small gold clusters (Au4, Au5 and Au8) supported on the anatase-TiO2(101) surface. In a variety of situations (with or without the supported gold cluster, with a varying amount of coadsorbed water or hydroxyl groups, etc.) we have investigated the stability of the bidentate propoxy species adsorbed at TiO2, as well as the barrier for its desorption into propene oxide. In all cases, the bidentate propoxy bonded at two surface Ti sites is highly stable, with a binding energy of the order of 1.5 eV. Such stability leads to very high energy barriers for propene oxide formation, of almost 2 eV. This suggests that such species is likely to be an spectator. Alternative reaction pathways, with the propoxy species formed in direct contact with the gold catalyst, are a much more probable candidate for a true reaction intermediate towards propene oxide formation.



中文翻译:

从头开始研究锐钛矿型TiO 2负载金纳米催化剂上环氧丙烷的形成

负载在TiO 2上的小金颗粒是丙烯直接环氧化的有前途的催化剂。一些实验研究表明,氧化物/金界面区域的关键作用是在反应过程中形成双齿丙氧基。然而,还不清楚这种络合物是否是真正的反应中间体,而不是纯粹的旁观者甚至是失活的物质。为了澄清这个问题,我们对由锐钛矿型TiO 2负载的小金簇(Au 4,Au 5和Au 8)形成的模型催化剂上的环氧丙烷形成进行了从头开始的广泛模拟。(101)表面。在各种情况下(有或没有负载的金簇,共吸附水或羟基的数量不同等),我们研究了吸附在TiO 2上的双齿丙氧基物种的稳定性以及其对TiO 2的阻挡作用解吸成环氧丙烷。在所有情况下,在两个表面Ti位点结合的双齿丙氧基都是高度稳定的,结合能为1.5 eV。这样的稳定​​性导致形成环氧丙烷的能量垒非常高,几乎达到2 eV。这表明这种物种很可能是旁观者。形成丙氧基与金催化剂直接接触的其他反应途径是真正的反应中间体向环氧丙烷形成的更可能的候选途径。

更新日期:2020-03-05
down
wechat
bug