Pd/Ce-HMS介孔材料的结构和表面化学态

为了制备新型负载型Pd催化剂，采用合成后组装法和浸渍法室温合成了Pd/Ce-HMS介孔材料，产物用XRD、N2吸附、FTIR及XPS谱等手段进行表征。结果表明，Ce、Pd引入后六方介孔结构仍保持完好。产物的BET表面积为742.9 m2·g-1，孔容0.803 cm3·g-1，表面Pd、Ce物种主要以PdO2和CeO2形式存在。研究表明，Ce前驱体通过与孔表面富集的Si—OH基团作用而嵌入骨架或键合于孔表面，Pd担载时由于模板剂仍留在孔道中，因而没有造成孔道堵塞。

Structure and surface chemical state of Pd/Ce-containing hexagonal mesoporous silicas

Pd/Ce-containing hexagonal mesoporous silicas(HMS) materials were synthesized by the post-assembly and impregnation methods in order to prepare new type Pd supported catalysts.Structure and surface chemical state of the products were characterized with powder X-ray diffraction patterns(XRD), N2 adsorption, Fourier-transform infrared spectra(FT-IR) and X-ray photoelectron spectroscopy(XPS), etc.The results showed that ordered hexagonal mesostructure were kept well after Ce and Pd species were assembled with Brunauer-Emmett-Teller(BET) surface areas 933.4 m2·g-1 and pore volume 0.803 cm3·g-1.Ce and Pd surface species were mainly PdO2 and CeO2.Cerium was incorporated presumably into the framework and/or into the walls of silica matrix of HMS structure by the reaction with the pore surface Si—OH groups,and clogging of channels with Pd clusters was avoided by introducing the reagent when the surfactant template was still present in the mesoporous channels.