期刊
ACS CATALYSIS
卷 5, 期 2, 页码 1100-1111出版社
AMER CHEMICAL SOC
DOI: 10.1021/cs5017062
关键词
gold; copper; spinel support; selective oxidation; propylene; acrolein; mechanism
Gold nanoparticles supported on a MgCuCr2O4 spinel catalyze the aerobic oxidation of propylene to acrolein. At 200 degrees C, the selectivity is 83% at a propylene conversion of 1.6%. At temperatures above 220 degrees C, propylene combustion dominates. The good performance of Au/MgCuCr2O4 in selective propylene oxidation is due to the synergy between metallic Au and surface Cu+ sites. Kinetic experiments (H-2 addition, N2O replacing O-2) show that the reaction involves molecular oxygen. DFT calculations help to identify the reaction mechanism that leads to acrolein. Propylene adsorbs on a single Au atom. The adsorption of propylene via its pi-bond on gold is very strong and can lead to the dissociation of the involved Au atom from the initial Au cluster. This is, however, not essential to the reaction mechanism. The oxidation of propylene to acrolein involves the oxidation of an allylic C-H bond in adsorbed propylene by adsorbed O-2. It results in OOH formation. The resulting CH2-CH-CH2 intermediate coordinates to the Au atom and a support O atom. A second C-H oxidation step by a surface O atom yields adsorbed acrolein and an OH group. The hydrogen atom of the OH group recombines with OOH to form water and a lattice O atom. The desorption of acrolein is the most difficult step in the reaction mechanism. It results in a surface oxygen vacancy in which O-2 can adsorb. The role of Cu in the support surface is to lower the desorption energy of acrolein.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据