【摘要】 用乙二醇为还原剂和碳黑分散溶剂,微波快速加热,1~2 MPa压力下制备了Pt/C和Pt-Ru/C催化剂,用XRD、TEM和XPS对其进行了表征。Pt/C和Pt-Ru/C催化剂活性金属平均粒径为1.9~2.0 nm。随Ru的加入,活性金属粒子的面心立方结构逐渐不明显。Pt-Ru/C中Pt以Pt(0)、Pt(Ⅱ)和Pt(Ⅳ)形式存在,Ru以Ru(0)和Ru(Ⅳ)形式存在。再将Pt/C、Pt-Ru/C催化剂与聚四氟乙烯一起负载于泡沫镍,得到疏水催化剂,研究了其对氢-水液相交换反应的催化活性。研究中观察到,Pt中掺入适量Ru可提高单一Pt基疏水催化剂的催化活性。其可能的原因是:水在Pt表面不解离,Pt表面氢气与水间同位素交换通过形成中间体(H2O)nH+(ads)(n≥2)进行,而水在Ru表面会发生解离,Pt-Ru疏水催化剂同时存在另一条反应路径。更多还原

【Abstract】 Pt/C and Pt-Ru/C catalysts with different ratios of Pt to Ru were synthesized,using ethylene glycol as both the dispersant and reducing agent at 1-2 MPa by microwave-assisted method.The catalysts were characterized by XRD,TEM and XPS.The mean particle sizes of the Pt/C and Pt-Ru/C catalysts were 1.9-2.0 nm.Pt and Ru existed as Pt(0),Pt(Ⅱ),Pt(Ⅳ),Ru(0) and Ru(Ⅳ) for Pt-Ru/C catalysts,respectively.The face-centered cubic structure of the active mental particles would be changed upon the addition of Ru gradually.Then polytetrafluoroethylene and carbon-supported Pt and Pt-Ru catalysts were supported on foamed nickel to obtain hydrophobic catalysts.The catalytic activity was increased for liquid phase catalytic exchange(LPCE) when uniform Pt based hydrophobic catalysts was mixed into appropriate Ru.Hydrogen isotope exchange reaction occurs between hydration layer(H2O)nH+(ads)(n≥2) and D atoms due to intact water molecules being on Pt surface for LPCE.Water molecules have a tendency to dissociate to OH(ads) and H(ads) on metal Ru surface,and there is the other reaction path for Pt-Ru binary catalysts,which is probably the main reason of the increase of the catalytic activity of the hydrophobic Pt-Ru catalyst.更多还原