Pd负载羟基多孔有机聚合物催化硅烷与醇脱氢偶联反应

Hydroxyl-functionalized porous organic polymers stablizing palladium nanocatalysts for the catalytic dehydrogenative coupling reaction of silanes with alcohols

摘要:

分别以甲苯、苯酚和邻苯二酚为单体，通过Friedel-Crafts反应制备三种多孔有机聚合物（POP）载体，通过浸渍、还原将Pd纳米粒子负载POP载体上，制备三种羟基含量不同的Pd/POP催化剂。通过FTIR、XRD、XPS、SEM及TEM表征催化剂的组成结构和微观形貌，探究催化剂表面羟基含量对Pd/POP催化剂催化二甲基苯基硅烷（硅烷）与乙醇脱氢偶联合成二甲基苯基乙氧基硅烷（硅醚）反应的影响。结果表明，Pd/POP催化剂表现出良好的催化活性，硅烷转化率和硅醚选择性大于99%；催化剂表面羟基含量越高，与Pd纳米粒子的相互作用越强，催化剂循环稳定性也越好，以邻苯二酚为单体制备的催化剂Pd/POP-OH-2循环使用7次，硅烷转化率和硅醚选择性未明显改变；Pd/POP-OH-2适用于多种硅烷（苯硅烷、二苯基硅烷、三苯基硅烷）与醇（甲醇、乙醇、正丙醇、异丙醇或正丁醇）的脱氢偶联反应，目标硅醚产率在34%~99%。

Abstract:

A series of porous organic polymer (POP) supports were synthesized by simple Friedel-Crafts reactions using toluene, phenol, and hydroquinone as monomers. Pd nanoparticles were loaded onto the supports through impregnation and reduction, resulting in a series of porous organic polymer-supported Pd nano-catalysts with varying hydroxyl contents. The catalysts were characterized using FTIR, XRD, XPS, SEM, and TEM. The effect of surface hydroxyl groups on the catalytic dehydrogenative coupling reaction of silanes with alcohols was investigated. The results showed that the more surface hydroxyl groups on the catalyst, the stronger the interaction with Pd, leading to the best catalyst cycling stability (no significant changes in conversion and selectivity after 7 cycles). Furthermore, these catalysts exhibited excellent activity (conversion of dimethylphenylsilane >99%) and selectivity (selectivity of dimethylphenylethoxysilane >99%) in the catalytic dehydrogenative coupling reaction between dimethylphenylsilane with ethanol. Additionally, catalysts with hydroxyl groups were also suitable for the dehydrogenative coupling reactions of various silanes and alcohol substrates (targeted silyl ethers yields ranging from 34% to 99%).