Preparation And Catalytic Performance Of MOF-derived Metal Oxide-supported Palladium Catalyst

The Suzuki-Miyaura reaction is the Pd-catalyzed cross-coupling of an organoboron reagent and an organic halide or sulfonate.This reaction has become arguably the most efficient method for aryl-aryl bond formation.The mild reaction conditions,wide functional group compatibility,high turnover rate,stable and low toxicity of organoboron reagents,and a wide range of sources.That can be widely used in different fields such as fine chemicals,pharmaceutical synthesis,pesticides and organic materials.It has a wide range of applications from millimolar to industrial kilogram scale synthesis.The development from homogeneous catalysts to heterogeneous catalyst,phosphine ligands are no longer necessary,and the activity of catalysts has been improved,but there are still many problems with Suzuki coupling catalysts,such as catalyst stability and persistence,aggregation inhibition,increase in active catalytic sites,and recycling properties.The toxicity of palladium leads to problems in contamination of the final product,limiting the industrialization of coupling reactions,etc.In this thesis,materials with large interfaces and catalytic sites were used as heterogeneous catalysts loaded with palladium,so MOFs-derived metal oxides were chosen as the carrier-loaded palladium catalysts to investigate the feasibility of catalyzing Suzuki coupling reactions.(1)ZIF-67 cubic polyhedral structure was synthesized by cobalt nitrate and 2-methylimidazole,the calcined metal oxide Co O_x@C was used as a carrier,and low content Pd catalysts was supported by the method of equal volume impregnation to synthesize the heterogeneous catalyst Pd/Co O_x.The structure and morphology of the catalysts were analyzed by a series of characterization methods such as SEM,XRD,EDX-Mapping,XPS,HR-TEM and ICP-OES.(2)The crystal structure of Zn Co-ZIF67 bimetallic cubic polyhedron was synthesized by zinc nitrate,cobalt nitrate and 2-methylimidazole,and the calcined metal oxide Zn O-Co Ox was used as the carrier,and the palladium was supported by the precipitation deposition method.onto the carrier and calcined to form the catalyst Pd/Zn O-Co O_x.The structure and morphology of the catalysts were analyzed by a series of characterization methods such as SEM,XRD,EDX-Mapping,XPS,HR-TEM and ICP-OES.The above prepared catalysts were applied to the Suzuki coupling reaction of aryl halides and aryl boronic acids,and the optimal reaction conditions were also investigated by varying the calcination temperature of the catalysts and screening the reaction time,temperature and solvent to obtain the optimal reaction conditions.Under the optimal reaction conditions,the suitability of the substrates was explored using halogenated benzene and phenylboronic acid derivatives as substrates.