还原温度对Pt/PTFE/泡沫SiC规整疏水催化剂性能的影响

摘要

为研究还原温度对Pt/PTFE/泡沫SiC规整疏水催化剂性能的影响,以200、225、250、275、300℃为还原温度,氯铂酸-乙醇溶液为浸渍溶液,采用浸渍-气相还原法制备Pt/PTFE/泡沫SiC规整疏水催化剂.利用接触角测试仪分析还原温度对催化剂疏水性能的影响,利用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电镜(TEM)等表征手段分析所得催化剂的结构与组成,并研究其氢-水液相催化交换(LPCE)性能.结果表明:还原温度的变化对催化剂疏水性能没有影响;还原温度200、225℃时催化剂中Pt粒子团聚现象严重,Pt粒子粒径大,分散性差;还原温度250、275、300℃时催化剂中Pt粒子粒径分散性较好;还原温度275℃时催化剂中Pt粒子粒径较窄,平均粒径最小,为6.2 nm.Pt存在Pt(0)、Pt(Ⅱ)和Pt(Ⅳ)三种价态,还原温度275℃下催化剂中0价Pt所占比例高达72.50％,还原程度高.LPCE催化交换性能也表明,还原温度275℃时催化剂柱效率最高.揭示275℃是所选取还原温度中的最佳还原温度.%To study the influence of reduction temperature on the performance of Pt/PTFE/foam SiC structured hydrophobic catalyst,200,225,250,275,300 ℃ were chosen as the reduction temperatures to prepare the different catalysts.The as-prepared catalysts were characterized by dynamic contact angle measurement,XRD,XPS,TEM,etc,moreover,their catalytic activity for LPCE was tested.Result shows that reduction temperature has no effect on the catalyst hydrophobicity.Bad dispersion and obvious aggregation are observed in the catalysts reduced by 200 ℃ and 225 ℃.Among the five catalysts,the catalyst reduced by 275 ℃ has the least size distribution and the smallest average particle size of Pt particles.Three valences,Pt(0),Pt(Ⅱ) and Pt(Ⅳ) exist in these catalysts,and Pt(0) is the key for catalytic isotope exchange.Pt(0) proportion of the catalyst reduced by 275 ℃ is the highest of the five ones.The catalytic activity of the catalyst reduced by 275 ℃ is also the highest for LPCE among these catalysts.Thus,275 ℃ is the best one of the chosen reduction temperatures for Pt/PTFE/foam SiC.