PTFE含量对Pt/C/PTFE疏水催化剂氢水液相催化交换性能的影响

Catalytic Activity of Hydrophobic Pt/C/PTFE Catalysts of Different PTFE Content for Hydrogen-Water Liquid Exchange Reaction

  • 摘要: 研究采用液相还原法制备10%Pt/C催化剂,再将其与PTFE一起负载于多孔金属载体,制备Pt/C/PTFE疏水催化剂。用XRD表征Pt/C催化剂上Pt晶相结构和粒径大小,Pt粒子平均粒径为3.1 nm;SEM表征PTFE与Pt/C催化剂的分散状态,二者基本混合均匀,局部地方有因未均匀分散而形成的PTFE膜。由于催化剂疏水性不够,PTFE与Pt/C质量比为0.5∶1时,Pt/C/PTFE催化剂活性较低,比例增至1∶1,催化剂活性明显增加,而继续增加PTFE比例,有更多的Pt活性位被包覆在PTFE中,同时催化剂内扩散效应增加,催化剂活性又逐渐降低。对多孔金属载体预处理,PTFE与Pt/C质量比为0.5∶1时,Pt/C/PTFE催化剂活性增加,而比例升为1∶1时,催化剂活性降低。

     

    Abstract: 10%Pt/C catalysts were prepared by liquid reduction method. PTFE and Pt/C catalysts were adhered to porous metal and hydrophobic Pt/C/PTFE catalysts were prepared. The structure and size of Pt crystal particles of Pt/C catalysts were analyzed by XRD, and their mean size was 3.1 nm. The dispersion state of Pt/C and PTFE was analyzed by SEM, and they had good dispersion mostly, but PTFE membrane could be observed on local parts of Pt/C/PTFE surface. Because of low hydrophobicity, Pt/C/PTFE catalysts have low activity when the mass ratio of PTFE and Pt/C is 0.5∶1, and their catalytic activity increases markedly when the ratio is 1∶1. When the ratio increases again, more Pt active sites would be covered by PTFE and interior diffusion effect would increase, which result in the decrease of catalytic activity of Pt/C/PTFE. By PTFE pretreatment of porous metal carrier, the activity of Pt/C/PTFE catalysts decreases when the mass ratio of PTFE and Pt/C is 0.5∶1, and their activity decreases when the mass ratio is 1∶1.

     

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