Synthesis Of Metal-organic Framework Compounds And Study On Methane Adsorption Properties

Metal-organic framework is a new type of porous material ,which is the fastest growing over the last decade. As MOFs show rich, adjustable structure, various pore channels, high surface area, including unsaturated metal coordination and other features, they are widely used in reaction catalysis, gas storage and separation etc.Especially, they are widely recognized and have a bright prospect in gas storage. Metal-organic framework compound MOF-5 is a typical structure among metal-organic framework compounds, which is of a three dimension cubic structure and shows better storage behavior due to high surface area, uniform pore and large pore volume. Furthermore, metal-organic framework compound PCN-14 was recently reported by foreign studies.By far,it is the largest methane storage MOFs.In this study, the metal-organic framework compound MOF-5 was synthesized by stirring at room temperature, using Zinc acetate as zinc source, N,N-dimethyl- formamide(DMF) as solvent and triethylamine (TEA) as the deprotonation agent. By the method of immersing and vacuum heating,MOF-5 completed its activation. Also, it was characterized by XRD and nitrogen adsorption-desorption, and completed methane adsorption test at a certain temperature and pressure. Otherwise, metal- organic framework compound PCN-14 also was tried to synthesis in this artical.The results of the study show that the metal-organic framework compound MOF-5 was successfully synthesized by stirring at room temperature, strictly preventing the participation of water by solvent drying, vacuuming and nitrogen protection. Solvent particles in the pores and the particle clearance of MOF-5 were well cleared,using DMF wash, soak and a certain amount of chloroform which was replaced once every 8 hours, a total of eight, soak at 70℃. Nitrogen adsorption-desorption test showeed that the BET surface area of MOF-5 was 2776.9020 m2/g and the pore size is uniform, to be about 0.88nm. The excess methane-adsorption capacity of actived MOF-5 powder was up to7.0526 mmol/g at T=295.15K,P=3.937MPa. With the increasing in bulk density, methane- adsorption capacity of samples was lower. Samples showed excellent repeat performance by several tests for methane charge and discharge.By curve fitting,isosteric heat of methane adsorption was 213.2 kJ mol-1 at T=295.15K. Some valuable experience was gained in the process of the synthesis of PCN-14.