Study On The Preparation Of Phosphine-Functionalized Organic Porous Polymers And Their Applications For The Catalytic Conversions Of CO And CO₂

Organic porous polymers have emerged as a new class of porous materials just in a few years ago.For their excellent physicochemical properties,such as excellent structural designability and large specific surface area,they showed potential applications for the development of new heterogeneous catalysts.On the other hand,phosphine ligands have been widely used in homogeneous carbonylation reactions.Therefore,it is of great practical significance to develop phosphine-functionalized organic porous polymer catalysts for carbonylation reactions with CO or CO₂ as the carbonyl sources.In this dissertation,synthesis of phosphine-functionalized organic porous polymers and their catalytic applications for the conversions of CO and CO₂ were studied.The main research results are as follows:1)A phosphorus-functionalized porous organic polymer-supported palladium?Pd@POP-Ph₃P?was successfully prepared via immobilizing Pd?OAc?₂ on porous polymeric phosphine ligand?POP-Ph₃P?.Catalytic performances of Pd@POP-Ph₃P were investigated in carbonylative Suzuki coupling and alkoxycarbonylation of aryl halides.The results suggested that Pd@POP-Ph₃P exhibited excellent catalytic activities in the two case reactions,and it outperformed the homogeneous Pd Cl₂?PPh₃?₂.Moreover,Pd@POP-Ph₃P showed excellent stability and reusability,and could be reused for at least 5 times.The excellent catalytic activities and stability could be attributed to the high phosphorus concentration and hierarchical pore structure of the catalyst.The high ligand concentration provides abundant coordination sites,while the hierarchical pore structure benefits the high dispersion of palladium species and the diffusion of reactant.2)Due to the quantum size effects and high surface area,noble metal nanoparticles?NPs?with small diameters?1-10 nm?have been the focus of catalysis research.Therefore,palladium nanoparticles stabilized by phosphine-functionalized porous organic polymer?Pd NPs@POP-Ph₃P?was successfully prepared.We demonstrated the use of the Pd NPs@POP-Ph₃P for catalytic carbonylation of chloroacetates to dialkyl malonates.Under the optimal conditions,Pd NPs@POP-Ph₃P exhibited good catalytic activity and reusability for the carbonylation of chloroacetates.The conversion of ethyl chloroacetate could be up to 97.7%,and the yield of malonate was 94.9%.Furthermore,the developed Pd NPs@POP-Ph₃P was also highly active for the alkoxycarbonylation of?-chloro ketones.3)Using CO₂ as C1 resource to synthesize carbonyl compounds is of great significance for the sustainable development of energy and environment.Toward this end,dual hydroxyls-functionalized polymeric phosphonium bromide?PQPBr-2OH?was prepared with POP-Ph₃P as the precursor.Physicochemical characterizations suggested that PQPBr-2OH possessed large surface area,hierarchical pore structure,and high density of active sites.Consequently,it behaved as an efficient,recyclable and metal-free catalyst for additive and solvent free cycloaddition of epoxides with CO₂.The conversion and selectivity of the catalytic reactions can reach above 99%.Comparing the activity of PQPBr-2OH with that of the reference catalysts suggested that hydroxyl functionalities in PQPBr-2OH showed a critical promotion effect on its catalytic activity for CO₂ conversion.Moreover,PQPBr-2OH was proved to be quite robust and recyclable.It could be reused at least ten times with only slight decrease of its initial activity.