铂基疏水催化剂制备及其在氢-水液相催化交换中的应用

Preparation and Characterization of Hydrophobic Platinum Catalyst for Hydrogen Isotope Exchange between Hydrogen and Liquid Water

采用浸渍-液相还原法合成Pt/C催化剂,以聚四氟乙烯(PTFE)为疏水材质,多孔陶瓷球为支撑载体制备出0.8wt%Pt-C-PTFE的球形(φ5.5 mm)疏水催化剂。通过透射电镜(TEM)、X射线能谱(XPS)和扫描电镜(SEM)等分析了催化剂的物理性能,液相催化反应进行了水去氘化的氢同位素交换性能表征。结果表明,Pt/C催化剂中金属铂负载量小于20%时,铂粒子平均粒径可以控制在2.4 nm左右。铂粒子价态为Pt0、Pt2+、Pt4+,其中零价态铂含量约为60%。金属铂负载量、疏水催化剂的装填比及交换温度对其总传质系数有较大影响。纳米铂单质和其氧化物共同作用实现催化交换。

The carbon-supported Pt catalyst was synthesized via the impregnation-liquid-reduction method. Polytetrafluoroethene （PTFE） was used to bind the carbon-supported Pt catalyst and the inert carrier and water-proof the catalyst, where porous ceramic spheres （5.5 mm in diameter） were used as the inert carrier for hydro- phobic catalysts （0.8% Pt-C-PTFE）. The physical properties of the catalyst were characterized by X-ray photoelectron spectroscope （XPS）, transmission electron microscope （TEM） and scanning electron microscope （SEM）, and the separation of deuterium from liquid water was carried out by liquid phase catalytic exchange （LPCE） reactions. As a result, the mean particle size of Pt particles in Pt/C catalyst is about 2.4 nm when the Pt loading is less than 20%. The Pt0, Pt2＋ and Pt4＋ are co-existed in the catalyst, with Pt0 content of about 60%. It is also found that the content of loaded-Pt, catalyst packed ratio and catalytic exchange temperature are the main factors in determining the overall mass transfer coefficient of hydrogen-water diffusion and exchange, which occur on Pt and its oxides active sites.