A Study On Synthesis, Structure And Adsorption Properties Of Gaseous Pollutants Of Coordination Polymers

In support of Guangxi Universities Scientific Research Project (Polythioether bagasse cellulose modified and capture persistent pollutants.201203YB061) and Guangxi University for Nationalities Research Foundation (A study on synthesis, structure and adsorption properties of metal-organic frameworks.2011MDYB041). As to air pollution of CO2and SO2in China, we synthesize a new Metal-organic Frameworks (MOFs) by hydrothermal method, and take it as a new adsorbent to adsorption typical gaseous pollutants, CO2and SO2. Explore the adsorption properties, adsorption kinetics equation, adsorption thermodynamic parameters and adsorption mechanism, of MOFs. And carry out cross-application of new materials in the control of gaseous pollutants in order to provide theoretical support and technical guidance for the prevention and control of air pollution in China. The main contents and results of the paper are as follows:(1) Take1,3,5-Benzenetricarboxylic acid as organic ligand and Zn(NO3)2·6H2O as metal ions, synthesize of [ZnNa(H3btc)(H2O)2](H2O)2of coordination polymers. X-ray single crystal diffraction data show, the coordination polymer belongs to the triclinic crystal system, Zn2+is pentacoordinated tetrahedral mode and coordinates with five oxygen atoms. The two Na atoms have a distorted octahedral coordination mode, two Na atoms and coordinates with two water ligand and four carboxylic acid ligand; IR spectra show,3155cm-1combined with the O-H stretching vibration, which shows that the water molecules present in the coordination polymers and the formation of hydrogen bonds. The C=O stretching vibration absorption peak at1613cm-1, which shows that the carboxyl deprotonated and Coordinates successfully. Analysis of the specific surface area and pore showed that, the surface area of complexes is large, BET surface area is181.92m2/g, the average pore size is 1.223840nm, one part is the hole, one part is the micropores. Thermogravimetric analysis curve shows that complexes hot weight loss is twice. The first occurred at50℃to200℃, weight loss is of about20%; The second occurred at350℃～580℃, weight loss is of about50%, which shows that the complex structure is more stable and does not decompose below350℃.(2) In pressure is20bar and temperature is20℃,40℃and60℃,[ZnNa(H3btc)(H2O)2](H2O)2adsorption of CO2and SO2gas dynamics test results show that, elevated temperatures can shorten the absorption time, but it also reduces the amount of the complex adsorption of CO2and SO2saturated. The proposed second-order equation can be well described by [ZnNa(H3btc)(H20)2]-(H2O)2adsorption of CO2and SO2, the activation energy were5.062123and5.182881kJ/mol. This shows that the complex adsorption of CO2and SO2in the process of physical adsorption.[ZnNa(H3btc)(H20)2]-(H2O)2adsorption of CO2and SO2gas PCT test results show, adsorption isotherms complexes of can be used Langmuir adsorption isotherm model well fitted, complex adsorption of CO2and SO2is the monolayer adsorption.△H°are-22.3734and-7.18521kJ/mol, The adsorption is an exothermic process.△S°are-90.02216and-40.55655J/mol-k. Gaseous pollutants transfer from the gas phase to the solid phase, the adsorption reduces the degree of disorder of the gaseous pollutants in the solid phase-gas interface.-20kJ/mol<△G°<0, the adsorption process is physical adsorption process, the adsorption reaction can spontaneously reach equilibrium.(3) Take1,2-diaminobenzene and2-Picolinic acid as organic ligand and ZnSO4as rnetal ions, synthesize of C12H9N3O10Zn2of coordination polymers. X-ray single crystal diffraction data show, the coordination polymer belongs to the Monoclinic crystal system, coordination mode of Zn2+is distorted octahedral. Zn2+and imidazole carboxylic acid side of the formation of a five-member chelating ring. Zn2+and on another ligand carboxylic acid O atom coordination, Zn2+and on another ligand carboxylic acid O atom coordination. The remaining one with the water. IR cpectra show,3031cm-1combined with the O-H stretching vibration, which shows that the water molecules present in the coordination polymers and the formation of hydrogen bonds. The C=O stretching vibration absorption peak at1645cm-1, which shows that the carboxyl deprotonated and Coordinates successfully. Analysis of the specific surface area and pore showed that, the surface area of complexes is large, BET surface area is316.86m2/g, the average pore size is0.998268nm, one part is the hole, one part is the micropores. Thermogravimetric analysis curve shows that complexes hot weight loss is twice. The first occurred at30℃to220℃, weight loss is of about5%; The second occurred at300℃to700℃, weight loss is of about40%, which shows that the structure of the complex begins to decompose when the temperature is higher than220℃,(4) In pressure is20bar and temperature is20℃,40℃and60℃, C12H9N3O10Zn2adsorption of CO2and SO2gas dynamics test results show that, elevated temperatures can shorten the absorption time, but it also reduces the amount of the complex adsorption of CO2and SO2saturated. The proposed second-order equation can be well described by C12H9N3O10Zn2adsorption of CO2and SO2, the activation energy were9.39578and15.8717kJ/mol. This shows that the complex adsorption of CO2and SO2in the process of physical adsorption. C12H9N3O10Zn2adsorption of CO2and SO2gas PCT test results show, adsorption isotherms complexes of can be used Langmuir adsorption isotherm model well fitted, complex adsorption of CO2and SO2is the monolayer adsorption.△H°are-15.4971and-14.0894kJ/mol, The adsorption is an exothermic process.△S°are-69.19102and-65.47137J/mol·k. Gaseous pollutants transfer from the gas phase to the solid phase, the adsorption reduces the degree of disorder of the gaseous pollutants in the solid phase·gas interface.-20kJ/mol<△G°<0,the adsorption process is physical adsorption process, the adsorption reaction can spontaneously reach equilibrium.