Study On The Applications Of Ultramicroporous Metal-Organic Frameworks In Adsorptive Separation Of Light Hydrocarbons

The separation and purification of low carbon hydrocarbon mixture is one of the most important chemical processes in petrochemical industry.Currently,the widely used solvent extraction and low temperature distillation methods have disadvantages such as high energy consumption,high investment cost and poor selectivity.For alkyne,carbon dioxide,the separation and purification of effective and olefin industry is of great significance,such as low carbon capture the separation and purification of hydrocarbon mixture demand,put forward a series of superfine metal organic framework materials and investigate the mechanism of adsorption,explore its industrial application potential,for the innovation of traditional low carbon hydrocarbon separation technology.In this paper,metal-organic framework materials（MOFs）,as a new type of porous materials,have the advantages of high specific surface area,developed porosity,construction unit diversity,pore designability,excellent thermal stability and chemical stability,as well as its potential application value in the fields of separation,purification and gas storage.Therefore,we synthesized an ultramicroporous Cu-MOFs by the way of transition metal（copper）and different types of inorganic anion ligands and organic ligands self-assembly,and synthesized ultramicroporous Zr-MOF with excellent thermal and chemical stability by the way of coordination of high price metal（zirconium）and organic ligands.By testing the adsorption properties,separation capacity and selectivity of these materials for two-component and three-component mixtures for low carbon hydrocarbons（C₂）,the industrial application prospect of a series of ultramicroporous MOFs materials for low carbon hydrocarbon separation was verified.The specific work is as follows:In my first work,we synthesized for the first time a novel Hoffman type metal-organic framework material is Cu（bpy）NP,which based on sodium nitroprusside anionic ligand for the efficient separation of acetylene（C₂H₂）from two-and three-component mixtures.The single component gas adsorption isotherms show that Cu（bpy）NP has an efficient adsorption capacity of C₂H₂.The adsorption capacity of Cu（bpy）NP is 22.4cm³g^-1at298 K and 0.01 bar.The total adsorption capacities of CO₂and C₂H₄at 1.0 bar were25.1 mmol g^-1and 40.8 mmol g^-1,respectively.The material has the second-highest C₂H₂/CO₂selectivity（47.5）and the fourth-highest C₂H₂/C₂H₄selectivity（29.0）of rigid MOFs without open metal sites（OMSs）reported so far.The binding sites simulated by GCMC and DFT-D and the two-component mixtures of C₂H₂/CO₂（50/50,v/v）,C₂H₂/C₂H₄（1/99,v/v）and C₂H₂/CO₂/C₂H₄（25/25/50,v/v/v）dynamic penetration test of the three-component mixture further confirmed that Cu（bpy）NP can achieve efficient separation of C₂H₂and ultra-high C₂H₄yield under environmental conditions,which has great application prospects for the production of polymer grade ethylene（>99.9%）.In my second work,we report a Zr-MOF with excellent thermal and chemical stability（Zr-TCA）,which can selectively adsorb C₂H₂and C₂H₆from a three-component mixture of C₂H₂/C₂H₄/C₂H₆to achieve one-step purification of C₂H₄.The single component gas adsorption isotherms showed that the adsorption capacity of ethane（C₂H₆）was 2.3 mmol g^-1at 298 K and 1.0 bar,showing a high selectivity（2.72）for the mixed fractions of C₂H₆/C₂H₄（v/v,50/50）.For C₂H₆/C₂H₄（v/v,10/90）mixed group,the selectivity was higher（2.79）,which was further confirmed by the grand canonical Monte Carlo（GCMC）binding sites and distribution range of C₂H₆and C₂H₄under 298 K and 1.0 bar.At the same time,the experimental penetration test also showed that high purity C₂H₄（>99.9%）could be directly collected from the two-component mixture of C₂H₆/C₂H₄（50/50,v/v）and the three-component mixture of C₂H₂/C₂H₆/C₂H₄（1/9/90,v/v/v）at room temperature and pressure.In addition,a series of the adsorption and separation properties remain unchanged after cyclic experiment,which also proves the tremendous industrial application prospect of the material.