电导率法研究W/O微乳液中Pd纳米微粒的化学破乳负载

利用水-Tween-80-Span-80-环己烷微乳液合成了粒径为5~10 nm、高度分散的Pd纳米微粒. 结果表明，随着破乳剂用量的增大，含Pd微乳液与破乳剂的混合体系依次呈现微乳液、分层、胶体或微乳液体系. 破乳剂的亲水性与分子结构是影响破乳行为的主要参数. 利用混合物体系分层与再均相的临界区域，在微乳液浸渍a-Al2O3载体的同时，使其中的Pd纳米微粒破乳沉积，实现了Pd在载体表面的均匀负载. TEM及XPS分析表明，Pd的微粒粒径为10~20 nm, 以单质形态结合于载体表面.

Chemical Demulsification and Immobilization of Pd Nanoparticles in W/O Microemulsion by Conductivity Method

The well dispersed palladium nanoparticles with 5~10 nm in diameter were prepared in water-Tween-80-Span-80- cyclohexane microemulsion. The mixture composed of demulsifying agent and microemulsion presents subsequently microemulsion, delamination and colloid or microemulsion with the increase of amount of demulsifying agent. The hydrophilic property and molecular structure of demulsifying agent are considered as the main property factors affecting the demulsifying behavior. Adopting the critical region of delamination and homogenous system, the immobilization of palladium nanoparticles on the surface of support can be realized by simultaneous impregnation of a-Al2O3 support and chemical demulsifying. Analytical results of TEM and XPS show that Pd nanoparticles on the surface of support have the sizes of 10~20 nm in diameter and exist in Pd metallic state.