Preparing magnetic multicomponent catalysts via a bio-inspired assembly for heterogeneous reactions
Preparing magnetic multicomponent catalysts via a bio-inspired assembly for heterogeneous reactions
复制标题
DOI：
10.1039/c6ra12088a
复制
发表时间：
2016-07
期刊：
影响因子：
3.9
通讯作者：
Wentong Song;Shengyang Tao;Yong-xian Yu;Xu Du;Shuo Wang
中科院分区：
文献类型：
--
作者：
Wentong Song;Shengyang Tao;Yong-xian Yu;Xu Du;Shuo Wang
本文报道了一种制备磁性多孔催化剂的简便合成方法，其上使用焦性没食子酸（PG）辅助的层层（LbL）涂层交替负载各种无机化合物。PG在分级多孔二氧化硅的表面上形成粘附和还原层，然后可以在材料的表面上引入Pd、Al 2 O3、ZrO 2或FeOx。与常规浸渍法相比，PG层明显提高了催化剂的分散性，大大减少了金属氧化物催化剂的形成对孔的堵塞。同时，该层的还原性质有助于将Pd纳米颗粒的直径减小至5 ± 1.3nm。Fe 3+离子被PG层部分还原为Fe 2+，形成Fe 3 O 4，这赋予多孔催化剂以磁分离性能。所合成的多组分催化剂对Suzuki Miyaura偶联反应、还原反应、Knoevenagel缩合反应和Friedel-Crafts烷基化反应均表现出优异的催化活性。与传统浸渍法制备的催化剂相比，TOF值提高了2 ~ 4倍。多组分磁性催化剂对许多一锅多步级联反应也表现出上级催化性能。
This article reports a facile synthetic approach for preparing magnetic porous catalysts, on which various inorganic compounds are alternately loaded using a pyrogallic acid (PG)-assisted layer-by-layer (LbL) coating. The PG forms an adhesion and reductive layer on the surface of hierarchically porous silica, and Pd, Al2O3, ZrO2, or FeOx can then be introduced on the surface of the material. Compared with the conventional impregnation method, the PG layer obviously improves the dispersion of catalysts and greatly reduces the blocking of the pores, which is caused by the formation of metal oxide catalysts. At the same time, the reduction properties of the layer help to reduce the diameter of the Pd nanoparticles to 5 ± 1.3 nm. The Fe3+ ions are partially reduced into Fe2+ by the PG layer to form Fe3O4, which endows the porous catalysts with a magnetic separation property. The synthesized multicomponent catalysts show excellent catalytic activity for various reactions, including the Suzuki Miyaura coupling, reduction, Knoevenagel condensation and Friedel–Crafts alkylation reactions. The TOF values show an improvement of 2 to 4 times over those of the catalysts prepared by the traditional impregnation method. The multicomponent magnetic catalysts also exhibit superior catalytic performance for many one-pot multistep cascade reactions.