苯选择加氢制环己烯非负载型和负载型Ru-Zn催化剂的比较  

Comparison Between the Unsupported Ru-Zn Catalyst and the Supported Ru-Zn Catalyst for Selective Hydrogenation of Benzene to Cyclohexene

作　　者：孙海杰[1] 黄振旭[1] 陈建军[1] 窦晓亚 李永宇[1] 刘寿长[2] 刘仲毅[2] 

机构地区：[1]郑州师范学院化学化工学院环境与催化工程研究所,河南郑州450044 [2]郑州大学化学与分子工程学院,河南郑州450001

出　　处：《石油学报（石油加工）》2017年第4期646-654,共9页Acta Petrolei Sinica(Petroleum Processing Section)

基　　金：国家自然科学基金(21273205;21543011;U1304204);河南省科技攻关项目(162102210333);河南省高等学校重点科研项目(16A150025);河南省高校科技创新团队支持计划(16IRTSTHN001)项目资助

摘　　要：采用共沉淀法和浸渍-沉淀法分别制备了Ru负载量相同的非负载型Ru-Zn催化剂和负载型Ru-Zn@ZrO_2催化剂,并在ZrO_2作非负载型Ru-Zn催化剂分散剂、且其用量与负载型Ru-Zn@ZrO_2催化剂的载体ZrO_2用量相同的条件下,考察了它们催化苯选择加氢制环己烯性能的差异。并通过X-射线衍射(XRD)、透射电镜(TEM)、N2-物理吸附、X-射线荧光光谱(XRF)和X-射线光电子能谱(XPS)等手段对加氢前后催化剂进行了表征。结果表明,ZrO_2作分散剂时加氢过程中非负载型Ru-Zn催化剂可以比负载型Ru-Zn@ZrO_2催化剂从浆液中吸附更多Zn^(2+)。吸附的Zn^(2+)可以转移金属Ru上的电子,使Ru变为有利环己烯生成的缺电子的Ruδ+物种,而且还可以占据不适宜环己烯生成的强Ru活性位。同时ZrO_2作分散剂的非负载型Ru-Zn催化剂具有4.0nm适宜苯选择加氢制环己烯的最佳Ru粒径,而负载型Ru-Zn@ZrO_2催化剂的粒径仅2.7nm。因此,ZrO_2作分散剂的非负载型Ru-Zn催化剂得到了61.0%的最高环己烯收率,而负载型Ru-Zn@ZrO_2催化剂的最高环己烯收率仅42.7%。实验表明,ZrO_2作分散剂的非负载型Ru-Zn催化剂具有良好的稳定性和重复使用性。An unsupported Ru-Zn catalyst and a supported Ru-Zn@ ZrO2 catalyst with the same Ru loading were prepared by a co-precipitation method and an impregnation-precipitation method, and the difference of their catalytic performance for selective hydrogenation of benzene to cyclohexene under the conditions of ZrO2 as the dispersant for the unsupported Ru-Zn catalyst and similar dosage for the supported Ru-Zn @ ZrO2 catalyst was investigated. The catalysts before and after hydrogenation were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM ）, N2 physisorption, X-ray fluorescence （XR F ）, and X-ray photoelectron spectroscopy （XPS）. The results showed that the unsupported Ru-Zn catalyst could absorb much more Zn^2＋ from the slurry than the supported Ru-Zn @ ZrO2 catalyst. The Zn^2＋ absorbed could transform electrons from the metallic Ru, which turned the metallic Ru into the electron-deficient Ri^δ＋ speciessuitable for the formation of cyclohexene. Moreover, the Zn^2＋ absorbed also could cover the strong Ru active sites unfavorable for the formation of cyclohexene. Meanwhile, the unsupported Ru-Zn catalyst with ZrO2 as a dispersant had an optimum Ru particle size of 4. 0 nm good for the selective hydrogenation of benzene to cyclohexene, however, the supported Ru-Zn catalyst had a small particle size of 2. 7 nm. Consequently, the unsupported Ru-Zn catalyst gave a better cyclohexene yield of 61. 0% , and the supported Ru-Zn@ ZrO2 catalyst only gave a cyclohexene yield of 42. 7%. Moreover, the unsupported Ru-Zn catalyst with ZrO2 as a dispersant had a good stability and an excellent reusability.

关 键 词：苯 选择加氢 环己烯 非负载 负载 钌 锌 

分 类 号：O643[理学—物理化学]