The Preparation Of Three-dimensional Mesoporous Nano-spherical Catalyst And Its Application In Organic Synthesis In Aqueous Medium

Green Chemistry is the study of a science that uses a set of principles to reduce or eliminate harmful substances to human health and the environment during the design,development,and processing of chemical products.The pollution caused by the traditional chemical industry has been very serious.At present,the world produces 300million tons to 400 million tons of harmful waste every year,which causes harm to the environment and threatens the survival of human beings.Developing organic chemical reactions in water media can greatly reduce the environmental pollution caused by organic solvents.The key problem is to design efficient catalysts.In the field of catalysis,heterogeneous catalysts are also gradually replacing homogeneous catalysts to reduce the serious environmental pollution caused by the catalytic reaction.Therefore,the immobilization of homogeneous catalysts has attracted a lot of interest from researchers,which not only involves the immobilization of the catalyst,but also the choice of the carrier becomes more important.Ordered mesoporous materials are new types of nanostructured materials that were rapidly emerging in the 1990s.They were highly valued by the international physics,chemistry and materials sciences and quickly developed into one of the interdisciplinary research hotspots.The immobilization of the organometallic into the silica wall will result in a novel heterogeneous catalyst.This catalyst not only has structures similar to periodic mesoporous silicones?PMOs?^[1,2],but also can modify the chemical environment around the active sites by surface modification^[3-6].So far,our group has done a lot of work in the direction of organometallic bridged PMO catalysts,but these catalysts are mostly two-dimensional hexagonal?2D?P6mm long pores.In the catalytic organic reaction,long pores are not conducive to the adsorption and diffusion of molecules in the reaction.Therefore,in view of the research in the Appeal Group,a three-dimensional short-channel organic-organic hybrid mesoporous heterogeneous catalyst was prepared by copolymerization method,and the catalytic performance of the catalytic organic reaction was investigated.The main content of the paper can be summarized as the following two parts:Firstly,Mesoporous organometallic Pd?II?heterogeneous catalysts?PMO-Pd?II?-3D?were synthesized by surfactant self-assembly and copolymerization of organometallic palladium with ethyl-bridged organosilane.The catalyst has ordered three-dimensional cubic mesoporous structure and large specific surface area.Compared with the two-dimensional long-channel catalysts,the catalyst is not easy to block the channels,and has less influence on the diffusion and mass transfer of reactants.In the catalytic carbon-carbon coupling reaction,it exhibits the comparable catalytic activity as homogeneous catalysts.In addition,because of its good chemical stability,the catalytic activity of the catalyst did not decreased significantly after repeated use for four times.Secondly,In order to better develop the advantages of three-dimensional short-channel mesoporous organic-organic hybrid catalysts,the second part of this paper replaced PdCl₂[PPh₂?CH₂?₂Si?OEt?₃]₂ with RhCl[PPh₂?CH₂?₂Si?OEt?₃]_3.Under the same conditions,three-dimensional short-channel rhodium catalysts were synthesized and applied to Heck-type reaction.The experimental results show that the catalyst is relatively stable and the activity of the catalyst has not been significantly reduced after repeated recycling.