TiOx/SiO2复合载体上高分散Au催化剂的CO氧化性能

摘要

Supports have a significant effect on the dispersion and stability of Au nanoparticles because of the support–metal interaction. In the present work, TiOx/SiO2 composite supports were prepared by the surface sol-gel (SSG) method to enhance the binding strength between the metal and the support. The samples were characterized by low-energy ion scattering (LEIS) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and N2 physisorption (BET). The results showed that the TiOx species in TiOx/SiO2 were highly dispersed on SiO2 with the formation of Ti―O―Si linkages. The catalytic activity and stability for CO oxidation on Au/TiOx/SiO2 were significantly enhanced, because of the better dispersion of Au nanoparticles compared with Au/TiO2.%负载型Au催化剂中金与载体间存在相互作用，载体性质能够影响Au纳米颗粒分散度及稳定性。本文通过表面溶胶-凝胶(SSG)法制备了TiOx/SiO2复合载体，以期增加氧化物载体表面配位不饱和度从而使其具有较高的金属分散性，并利用低能离子散射(LEIS)谱、X射线光电子能谱(XPS)、X射线衍射(XRD)、透射电子显微镜(TEM)及N2物理吸附(BET)等手段对载体及催化剂进行表征分析。实验表明TiOx/SiO2复合载体表面TiOx分散性良好，没有形成明显的TiO2晶相，且与SiO2间形成Ti―O―Si键。与Au/TiO2相比， Au/TiOx/SiO2催化剂中Au纳米颗粒的分散性更好，因而CO氧化活性显著提高。 TiOx/SiO2复合载体上的TiO2膜是Au的主要表面键合位，导致Au与载体间相互作用增强，从而使得Au纳米颗粒抗烧结能力提高，同时催化剂反应稳定性得到改善。