沸石雏晶固定的铱基催化剂及其催化转移加氢性能

Iridium-based Catalyst Immobilized on Zeolite Subcrystals and Its Catalytic Transfer Hydrogenation Performance

将均相催化剂固定化能够同时保留均相催化剂高反应活性和多相催化剂易分离的优点.本文以具有超小尺寸、超大比表面积的沸石雏晶(Al-MFI-SC)作为载体,通过物理吸附法实现了均相转移加氢催化剂[Cp*Ir(bpyO)]OH~-的固定化,制备了固定化催化剂[Cp*Ir(bpyO)]OH~-/Al-MFI-SC.采用紫外-可见分光光度计对固定化过程和稳定性进行初步研究,确定了催化剂的固定量,并证明了该固定化催化剂的稳定性. X射线衍射仪、透射电子显微镜、电感耦合等离子体发射光谱、 Ar物理吸附-脱附和X射线光电子能谱等表征结果证明,[Cp*Ir(bpyO)]OH~-被均匀地固定在Al-MFI-SC表面,沸石雏晶中的铝物种与铱配合物之间的强相互作用是该固定化催化剂稳定的原因.将该催化剂用于以葡萄糖作为氢供体、环己酮转化为环己醇的催化转移加氢反应,在最佳实验条件下能够得到75.4%的环己醇产率.与铱含量相同的均相催化剂的催化反应结果相比,这种固定化催化剂展现出了更好的催化活性,同时具备良好的循环使用性能.

By immobilizing homogeneous catalysts,the advantages of high reaction activity of homogeneous catalysts and separability of heterogeneous catalysts can be preserved simultaneously.This work used zeolite subcrystals with ultra-small size and ultra-large specific surface area as the carrier to immobilize the homogeneous transfer hydrogena-tion catalyst[CpIr(bpyO)]OH-by physical adsorption,achieving the preparation of an immobilized catalyst[CpIr(bpyO)]OH-/Al-MFI-SC.The immobilization process and stability of the catalyst were preliminarily studied using UV-Vis to determine the amount of catalyst immobilized and demonstrate the stability of the immobilized catalyst.The characterization results of XRD,TEM,ICP-AES,Ar physical adsorption and desorption and XPS demonstrated that[CpIr(bpyO)]OH-was uniformly immobilized on the surface of Al-MFI-SC.The strong interaction between the aluminum species in the zeolite subcrystals and the iridium complex was responsible for the stability of the immobilized catalyst.Finally,The catalyst was used for the catalytic transfer hydrogenation of cyclohexanone to cyclohexanol using glucose as the hydrogen donor and able to achieve a cyclohexanol yield of 75.4%under optimal reaction conditions.Compared with the homogeneous catalyst with the same weight percent of iridium,this Chem.J.Chinese Universities,2023,44(10),20230224 immobilized catalyst showed better catalytic activity and good recycling performance.Meanwhile,the catalyst had a good reusability property.This work provides an idea for the preparation of immobilized catalysts for catalytic transfer hydrogenation reactions using zeolite subcrystal materials as the carrier.