堇青石表面化学气相沉积二氧化钛的负载机理及负载动力学

以酸蚀改性堇青石为基体，利用化学气相沉积法（CVD）在基体上负载TiO₂，采用扫描电子显微镜、能谱仪、X射线衍射仪、BET比表面积法等对负载了TiO₂的堇青石进行表征，测定不同温度下的负载速度。结果表明：负载了TiO₂的堇青石主要由（211）及（200）取向的锐钛矿TiO₂组成，呈八面体和立方体形态，BET比表面积达78.80 m²·g^-1，平均孔径为9.80 nm，具有双峰分布特征。负载过程为TiCl₄及O₂向堇青石基体扩散吸附，TiCl₄分解为Ti⁴⁺并在高氧势下进入基体晶格形成TiO₂晶核，并经过择优取向和外延式生长，其负载沉积速率方程为，其中T为负载温度，为气相TiCl₄的分压。

Loading Mechanism and Loading Kinetics of TiO2 on Cordierite Surface by Chemical Vapor Deposition

In order to explore the loading mechanism and loading kinetics of TiO₂ on cordierite, the acid-etched cordierite was used as the matrix and the TiO₂ loading test was conducted by the chemical vapor deposition (CVD) method. The scanning electron microscope, energy disperse spectroscope, X-ray diffraction, and Brunauer-Emmett-Teller (BET) specific surface area measurement were used to characterize the TiO₂ on cordierite surface and determine the loading speed at different temperatures. The results show that the surface of modified cordierite with TiO₂ mainly consists of (211)-oriented and (200)-oriented anatase-TiO₂ which is the octahedron and cube with BET specific surface area of 78.80 m²·g^-1, an average pore diameter of 9.80 nm, and a bimodal distribution. The loading process is the diffusion and adsorption of TiCl₄ and O₂ towards the cordierite matrix. TiCl₄ decomposes and Ti⁴⁺ enters the matrix lattice under the high oxygen potential to form TiO₂ nuclei. After the preferential orientation and epitaxial growth, the loading deposition rate equation is , where T is the loading temperature and is the partial pressure when TiCl₄ is in the gas phase.