巯基功能化介孔材料高效锚定钯负载型催化剂的制备及其苯酚加氢催化性能

Immobilization of highly active Pd nano-catalysts on functionalized mesoporous silica supports using mercapto groups as anchoring sites and their catalytic performance for phenol hydrogenation

以含巯基官能团有机硅烷修饰的介孔材料MCM-41和SBA-15为载体, 采用浸渍-氢气还原法制备了高分散和高活性的负载型Pd催化剂. X射线衍射、N2吸附-脱附和透射电子显微镜表征结果显示, 所制Pd催化剂Pd-SH-MCM-41和Pd-SH-SBA-15具有很好的长程有序结构、分布均匀的孔径、高比表面积及高度分散的Pd颗粒. 苯酚加氢反应结果表明, 以Pd-SH-MCM-41和Pd-SH-SBA-15为催化剂时, 在80oC, 1.0 MPa反应1 h, 苯酚转化率达99%以上, 环己酮选择性为98%. 它们的催化活性为商业Pd/C催化剂的5倍, Pd/MCM-41和Pd/SBA-15催化剂的3倍. 这可归因于介孔材料表面修饰的巯基官能团对Pd的锚定作用, 避免了Pd颗粒的团聚, 使其高度分散在介孔材料上.

Highly active and highly dispersed Pd‐loaded nano‐catalysts using mercapto group（-SH） functionalized mesoporous silica supports,namely,Pd‐SH‐MCM‐41 and Pd‐SH‐SBA‐15,were prepared using an impregnation‐reduction approach.The surface-SH groups are believed to facilitate the high distribution and immobilization of the Pd nanoparticles within the silica supports through an anchoring interaction.The catalysts featured long‐range ordered structures,uniform pore size,high surface area,and highly dispersed Pd nanoparticles as characterized by X‐ray diffraction,N2 adsorption‐desorption,and transmission electron microscopy.The catalysts showed activity five times higher than that of commercial Pd/C catalyst and three times higher than those of Pd/MCM‐41 and Pd/SBA‐15 catalysts.Within 1 h of reaction at 80 °C and 1.0 MPa,the conversion of phenol attained was greater than 99%,and the selectivity for cyclohexanone was 98%.