Graphene Supported Pd-Au Alloy Catalyst And Its Application In C-C Bond Coupling Reaction

In the past few decades,homogeneous catalysts have been widely used in chemistry because of their excellent catalytic activity,reaction selectivity,and fewer side reactions.However,homogeneous catalysts are difficult to separate from the reaction system and are not easy to recover and the catalyst It is difficult to achieve recycling and pose a greater threat to the environment.In order to solve the problem of environmental pollution caused by homogeneous catalysts,chemists proposed a supported catalyst system and prepared heterogeneous catalysts to reduce such problems.Therefore,heterogeneous catalysts were slowly discovered by scientists.The heterogeneous catalyst is easy to separate from the reaction substrate,and has many advantages such as recycling and reuse.Therefore,the heterogeneous catalyst prepared by supporting the homogeneous catalyst on various supports can effectively improve the stability and catalytic activity of the catalyst And reduce the cost of scientific research.Therefore,heterogeneous catalysts have gradually received widespread attention in the chemical community.In the classic nano-transition metal-catalyzed carbon-carbon bond cross-coupling reaction,our research group continuously explores new high-efficiency catalysts,optimizes the reaction conditions,and enables the coupling reaction to achieve the desired effect.This thesis takes green chemistry as the starting point and carries out related work around metal-catalyzed carbon-carbon bond coupling reactions.It is divided into three parts: 1)Use of cheap,readily available,non-toxic,hydrophobic,well-dispersed,and small-pore two-dimensional carbon Using nanomaterials as a carrier,a new graphene-supported Pd,Au alloy catalyst was prepared.The catalyst was characterized by XRD,TEM,elemental analysis,ICP-AES and other tests.Finally,4-methylaminopyridine was determined as the ligand.In the form of mixing and stirring and the complexation of metal and ligand,the transition metals Pd and Au were successfully loaded on the surface of graphene.The loading of graphene on palladium and gold was measured by ICP.The final result was the loading of Pd.Pd was0.0157 mmol /g,Au is 0.001 mmol/g.2)To explore the catalytic performance ofgraphene-supported Pd and Au alloy catalysts for carbon-carbon bond coupling reactions such as Heck reaction,Suzuki reaction,and Sonogashira reaction.Through optimization of the reaction system,when the amount of Graphene-Pd-Au is 3 mol-100 mol ppm,under the reaction conditions of 90 ?,the corresponding substrates are expanded for different reactions such as Heck reaction,Suzuki reaction,Sonogashira reaction,etc.,The final yield is80%-97%.When expanding the substrate for the reaction,the amount of catalyst we use is very low,which reduces the cost of the reaction and also solves the problem of heavy metal residues in the product.3)Graphene as a carrier,because it can provide a good microenvironment,we speculate that using graphene as a carrier may greatly promote organic conversion,so that it has higher catalytic activity and selectivity.In short,by modifying the surface of the graphene material,the modified graphene successfully developed a new,simple and efficient graphene-supported alloy catalyst through the role of complexing metal ions with ligands.The coupling reaction shows extremely high catalytic activity.The catalytic results of the above three carbon-carbon bond coupling reactions show that graphene as a carrier supporting transition metal catalyst has very good application prospects.