RESS技术制备负载型茂金属催化剂的表面特性研究

Surface Analysis and Characterization of Cp_2TiCl_2/PS Catalyst Prepared by Rapid Expansion of Supercritical Solution

用X-射线光电子能谱法分析了超临界溶液快速膨胀法制得的二氯二茂钛(Cp2TiCl2)颗粒、聚苯乙烯(PS)颗粒和二氯二茂钛/聚苯乙烯(Cp2TiCl2/PS)负载型颗粒的表面化学性质,得到了三种不同颗粒的表面元素组成及元素结合状况,发现只有聚苯乙烯(PS)颗粒在喷射过程中吸附CO2和标记物CH3CH2OH,而二氯二茂钛(Cp2TiCl2)颗粒和二氯二茂钛/聚苯乙烯(Cp2TiCl2/PS)负载型颗粒都不吸附CO2和CH3CH2OH,表明通过选择合适的操作条件,超临界溶液快速膨胀法制得的Cp2TiCl2/PS颗粒是以PS为内芯、Cp2TiCl2为外壳的负载型催化剂,为超临界溶液快速膨胀法制备负载型催化剂的新型工艺的可行性提供了依据。

The rapid expansion of supercritical solutions (RESS) is explored as a novel route to the formation supported catalyst microparticles. The superfine polystyrene powder coated with Cp2TiCl2 was coprecipitated by RESS. In order to identify surface characteristic of the supported particles, X-ray photoelectron spectroscopy (XPS) has been used to obtain surface chemical state of polystyrene particle, Cp2TiCl2 particle and Cp2TiCl2/PS particle prepared by RESS. By comparing the result of XPS analysis of reference particles (polystyrene particle and Cp2TiCl2 particle) to coated sample, it is found that both Cp2TiCl2 particle and Cp2TiCl2/PS particle don't adsorb small molecules Of CO2 and CH3CH2OH, while the polystyrene particle surface contains small molecules. The surface elemental distribution and chemical structure of three type particles' experimental results show clearly the uniform incorporation of polystyrene microparticles within Cp2TiCl2 microspheres, and thus, the feasibility of RESS as a technique for coprecipitation of supported catalyst. The thickness of the coating is about 2.637 similar to 3.515nm according to quantitative chemical analysis and XPS analysis of supported particle. The RESS technique is an effective tool to prepare the supported catalyst particles.