活性炭负载Pt-Ni双金属催化剂上甘油水溶液原位加氢反应性能

采用KBH4液相还原法制备了系列活性炭(AC)负载的Pt-M(M=Fe,Ni,Co,Zn,Cu)双金属催化剂,考察了该系列催化剂对甘油水溶液原位加氢制备1,2-丙二醇反应的催化性能.结果表明,当Pt负载量(质量分数)为2.0%,Pt/Ni质量比为1∶1时,在220℃和1.0 MPa氮气压力下反应8 h,2%Pt-2%Ni/AC催化剂上甘油转化率和1,2-丙二醇选择性分别达到98.7%和60.5%;且在5次重复使用过程中,催化剂保持较高的稳定性.采用氮气物理吸附-脱附实验、X射线衍射(XRD)、透射电子显微镜(TEM)、选区电子衍射(SAED)及X射线光电子能谱(XPS)等对催化剂的结构和形貌进行了表征.结果表明,粒径约为2 nm的纳米颗粒在活性炭载体上均匀分散,纳米粒子中金属多以还原态形式存在,Ni原子进入Pt晶格中形成的Pt-Ni物种使Pt与Ni之间表现出强相互作用力.通过比较Pt/AC,Ni/AC与Pt-Ni/AC双金属催化剂的催化性能,推断Pt能够促进甘油水溶液重整而Ni有利于氢解反应,Pt-Ni金属间协同作用是Pt-Ni/AC催化剂对甘油原位加氢反应具有优良催化性能的重要原因.

Catalytic Performance of Activated Carbon Supported Pt-Ni Bimetallic Catalyst for Glycerol in situ Hydrogenolysis

A series of activated carbon supported Pt-M( M=Fe, Ni, Co, Zn, Cu) bimetallic catalysts was prepared via KBH4 reduction method for glycerol in situ hydrogenolysis to produce 1, 2-propanediol. The results showed that Pt-Ni/AC catalyst with a Pt loading ( mass fraction ) of 2. 0% and a Pt/Ni mass ratio of 1:1 displayed excellent performance at 220℃ under 1. 0 MPa of N2 after 8 h reaction time, with a high selec-tivity of 60. 5% and a conversion of 98. 7%. In addition, the prepared Pt-Ni/AC had a good catalytic stabili-ty, which kept a high activity even after five cycles catalytic evaluation. The results from the characterization of catalysts by N2 physisorption, XRD, TEM and XPS indicated that nanoparticles with an average size of ca. 2 nm were uniformly dispersed on the support. And the majority of metals in nanoparticles are present in the zerovalent metallic state. The formation of Pt-Ni phase due to the incorporation of Ni in the Pt lattice was responsible for the strong interaction between Pt and Ni metal. The catalytic performance of Pt-Ni/AC was compared with that of Pt/AC and Ni/AC, it was clearly observed that Pt could promote the aqueous phase reforming of glycerol to hydrogen, and Ni could facilitate the hydrogenolysis of glycerol. The unique perfor-mance of Pt-Ni/AC bimetallic catalysts was attribute to the the synergistic effect between Pt and Ni.