Application Of Covalent Organic Frameworks In The Catalytic Conversion Of CO₂

The catalytic conversion of carbon dioxide(CO₂)is one of the main contents in the fixation and utilization of CO₂.Construction of stable and efficient catalytic systems is one of the central issues of the catalytic conversion of CO₂.Covalent organic frameworks(COFs)are a new type of crystalline organic porous materials,which are constructed with organic molecules through covalent bonds.The crystalline pore structures with tailored functionalities have offered COFs great potential in the heterogeneous catalytic conversion of CO₂.Accordingly,this thesis focused on the application of COFs in the catalytic conversion of CO₂.The main research work is summarized as follows:1.Synthesis of a catechol-functionalized COF and its application in the catalytic conversion of CO₂.A catechol-functionalized COF,LZU-101,was facilely synthesized via the Schiff-base chemistry.LZU-101 possesses a crystalline pore structure with a BET surface area of 1448 m²/g.With the catechol group in its structure,LZU-101 could be easily converted into a Co(II)-containing COF(Co@LZU-101).The catalytic activity of Co@LZU-101 was tested in the formylation of N-H bonds with CO₂.The results showed that Co@LZU-101 could catalyze the reaction under mild conditions(CO₂ 1atm,80 ^oC).2.Synthesis of guanidine-functionalized COFs and their catalytic application.Based on the alkalinity of the aliphatic guanidine moity,we attempted to construct guanidine-functionalized COFs for the adsorption and catalytic conversion of CO₂.However,two amorphous organic polymers(LZU-104 and LZU-105)were synthesized,and their activities in the catalytic conversion of CO₂ were tested.The results revealed that LZU-104 and LZU-105 had no catalytic activities,which may be attributed to the different electronic effect of aromatic guanidine moity.