24小时热门版块排行榜

返回列表

本帖产生 1 个 C-EPI ，点击这里进行查看

当前只显示满足指定条件的回帖，点击这里查看本话题的所有回帖

wandaohzl

荣誉版主 (著名写手)

C-EPI: 1
应助: 1 (幼儿园)
贵宾: 1.809
金币: 9422.3
散金: 5973
红花: 197
沙发: 4
帖子: 1834
在线: 416.7小时
虫号: 759399
注册: 2009-04-28
专业: 污染控制化学
管辖: 微米和纳米

[交流] 【建议】催化的一篇nature 大家看看现在最新的研究动态！已有159人参与

Controlled selectivity for palladium catalysts using self-assembled monolayers

ABSTRACT: The selective reaction of one part of a bifunctional molecule is a fundamental challenge in heterogeneous catalysis and for many processes including the conversion of biomass-derived intermediates. Selective hydrogenation of unsaturated epoxides to saturated epoxides is particularly difficult given the reactivity of the strained epoxide ring, and traditional platinum group catalysts show low selectivities. We describe the preparation of highly selective Pd catalysts involving the deposition of n-alkanethiol self-assembled monolayer (SAM) coatings. These coatings improve the selectivity of 1-epoxybutane formation from 1-epoxy-3-butene on palladium catalysts from 11 to 94% at equivalent reaction conditions and conversions. Although sulphur species are generally considered to be indiscriminate catalyst poisons, the reaction rate to the desired product on a catalyst coated with a thiol was 40% of the rate on an uncoated catalyst. Interestingly the activity decreased for less-ordered SAMs with shorter chains. The behaviour of SAM-coated catalysts was compared with catalysts where surface sites were modified by carbon monoxide, hydrocarbons or sulphur atoms. The results suggest that the SAMs restrict sulphur coverage to enhance selectivity without significantly poisoning the activity of the desired reaction.