Study On Catalytic Action Of Metal-organic Framework In Carbon Dioxide Conversion Reaction

Carbon dioxide,as one of the greenhouse gases,has drawn wide attentions due to its risks in the global environment and climate change.Chemically fixation and conversion of CO₂ to useful chemicals has been proved to be an effective solution to this problem.The key of which is finding an economic and stable catalyst that can promote the conversion of CO₂with high activity.As a new inorganic-organic hybrid porous material,MOFs?Metal-organic Frameworks?have many advantages such as easy synthesis,large specific surface area,high stability,variable structure,easy control and modification.It has potential application prospects in gas storage and separation,fluorescence,magnetism,catalysis and drug release,and has drawn wide attention of scientists from all over the world.The MOFs as a catalyst or catalyst support for the catalytic conversion of carbon dioxide has also been more reported.In this paper,the synthesis and classification of metal-organic frameworks are introduced.The progress of the research on the synthesis of propylene carbonate catalyzed by metal-organic frameworks is reviewed in this paper.The main contributions are summarized as follows:chemical catalysis,photocatalysis and electrocatalysis.In this paper,metal ions and organic ligands by solvothermal method to build five metal organic framework,as follows:In the first part,a novel 3D 4-fold-interpenetrating[Cu?tzbz?₂]·EtOH with Cu²⁺and 4-?1H-1,2,4-triazol-1-yl?benzoic acid as center metal ions and organic ligands was synthesized under solvothermal condition,and a novel 3D MOF named[Co₅?tzbz?₆?bpy?₂??₃-O?₂]·2H₂O·2DMF has been obtained through a mixed ligand approach using 4-?1H-1,2,4-triazol-1-yl?benzoic acid and 4,4-bipyridine under solvothermal condition.And their structure were thoroughly characterized by X-ray crystallography,PXRD,TGA,FT-IR characterizations.Then[Cu?tzbz?₂]·EtOH and[Co₅?tzbz?₆?bpy?₂??₃-O?₂]·2H₂O·2DMF was used to catalyzed the coupling reaction of CO₂ and epoxides.Moreover,the influences of various reaction parameters on catalytic activity were investigated,including reaction temperature,CO₂ pressure,reaction time.The catalytic tests demonstrated that[Cu?tzbz?₂]·EtOH has highly efficient catalytic activity for cycloaddition of propylene oxide with CO₂ into propylene carbonate at 80?under 2.5Mpa CO₂ pressure with a yield of 82%over 5h.The yield of propylene carbonate reached 80%at the optimized reaction conditions?70??2MPa and 4h?by[Co₅?tzbz?₆?bpy?₂??₃-O?₂]·2H₂O·2DMF.At last,based on the experimental phenomenon and experimental results,the self-catalyzed mechanism as well as synergistic mechanism with tetrabutylammonium bromide?Bu₄NBr?for CO₂ conversion was proposed.In the second part,The MOF-5 has been obtained with Zn²⁺and 1,4-benzenedicarboxylic acid as central metal ions and organic ligands under solvothermal condition.After that,a series of isostructural Ni-doped MOF-5 and Co-doped MOF-5 have been synthesized.And their structure were thoroughly characterized by X-ray crystallography,PXRD,TGA,FT-IR characterizations.Then MOF-5 Ni-doped MOF-5 and Co-doped MOF-5 was used to catalyzed the coupling reaction of CO₂ and epoxides.Moreover,the influences of various reaction parameters on catalytic activity were investigated,including reaction temperature,CO₂ pressure,reaction time.The catalytic tests demonstrated that MOF-5 has highly efficient catalytic activity for cycloaddition of propylene oxide with CO₂ into propylene carbonate at60?under 2Mpa CO₂ pressure with a yield of 92%over 4h.The yield of propylene carbonate reaced 92%at the optimized reaction conditions?100?,2MPa,6h?by Ni-doped MOF-5.The catalytic tests demonstrated that Co-doped MOF-5 has highly efficient catalytic activity for cycloaddition of propylene oxide with CO₂ into propylene carbonate at 90?under 2Mpa CO₂ pressure with a yield of 91%over 4h.At last,based on the experimental phenomenon and experimental results,the self-catalyzed mechanism as well as synergistic mechanism with tetrabutylammonium bromide?Bu₄NBr?for CO₂ conversion was proposed.