Preparation Of Metal-Organic Frameworks(MOF-177) And Adorption Of VOCs

The concentrations of pollutions in indoor air are usually2-100times higher than that in outdoor air. A number of the typical pollutions in indoor air are carcinogenic, teratogenic, and mutagenic, and pose great health risks to human bodies. Therefore, the indoor air quality should be improved by removing the air pullutants. Sorption by adsorbents is a useful thchnique for the removal of pollutants from air, for which the adsorbent is the most important thing. Metal-organic frameworks are a type of promising adsorbents in applications of gas separation and purification due to their high specific surface area and large accessible pore volume.In this study, MOF-177were synthesized from Zn(NO3)2·6H2O and benzenetribenzoate in N,N-dimethylactamide solution by the solvothermal synthesis method. The specific surface area, calculated by Langmuir model, of the systhesized MOF-177was4170m2/g. The cumulative pore, calculated by the Saito-Foley method, of the systhesized MOF-177was1.132cm3/g, and the median pore diameter was0.94nm. This material is stable even at the temperature up to400℃.MOF-177had high monolayer saturated adsorption capacities of volatile organic compounds (VOCs), including acetone, benzene, toluene, ethylbenzene, xylene and styrene. The monolayer saturated adsorption capacities of acetone and benzene were765mg/g (13.2mmol/g) and953mg/g (12.2mmol/g) obtained with static adsoprtion experiments, respectively. The saturated adsorption capacities of acetone and benzene were487mg/g (8.38mmol/g) and695mg/g (8.90mmol/g) obtained with dynamic adsoprtion experiments, respectively. We observed that the monolayer saturated adsorption capacities of VOCs on MOF-177decreased with the increasing of gas molecular cross-sectional areas. Moreover, the adsorption amounts of these eight VOCs obtained with dynamic adsoprtion experiments were lower than that obtained with static adsoprtion experiments. Therefore, we proposed that the tightness of VOCs molecules in dynamic adsorption experiments were weaker than that in static adsoprtion experiments due to the existence of air molecules. In dynamic adsorption experiments, the obtained saturated adsorption amounts of VOCs, such as ethylbenzene, xylenes and styrene, were almost the same if the cross-sectional areas of these VOCs molecules were almost equal.This phenomenon could be attributed to the steric interferences of different VOCs molecules which were counteracted by air molecules.