Avaliação do potencial de adsorção de água nas redes metalorgânicas NH2-MIL-125(Ti) e MIL-160(Al)

Abstract

The presence of water, in the gas composition of natural gas, has been one of the main points of study due to the problems related to the gas transportation and storage. Then, in order to avoid these problems, the dehydration process is applied in processing units in order to reduce the water vapor concentration in the gas composition. However, it is observed that the adsorbents used show saturation in a very short period of time, on the other hand, the metalorganic framework (MOF) has been presented as potential adsorbent materials of certain gaseous compounds through their characteristics of high surface area and thermal stability. The MILs MOFs NH2-MIL-125 and MIL-160 are stable and have a high affinity for water. Therefore, this work had the objective of evaluating the water adsorption of the MOFs above mentioned under static and dynamic conditions with multicomponents. The MOFs were synthesized and characterized by X-ray diffraction, infrared spectroscopy, thermogravimetric analysis and nitrogen adsorption / desorption techniques, and the results of these analyzes were successful in the synthesis process of materials with high adsorbent characteristics. The adsorption kinetics of water and adsorption in a fixed bed with multicomponent flows (N2/H2O) with the MOFs synthesized and a traditional adsorbent to the process of dehydration, a molecular sieve (Zeolite 3A, MS) were also carried out. By adsorption kinetics, MS, NH2-MIL-125 and MIL-160 behaved according to the pseudo-second order model and presented maximum adsorption capacity of 240.5 mg g-1, 516 mg g-1 and 347.2 mg g-1 , respectively. The adsorbents mentioned above had a water removal capacity in the range of 192.44 – 259.96 mg g-1 (MS), 192.44 – 259.96 mg g-1 (NH2-MIL-125) and 243.18 – 316.03 mg g-1 (MIL-160). In conclusion, the studied MOFs obtained superior water adsorption results in static conditions of dynamics in relation to the molecular sieve, and could be considered as a potential adsorbent for the gas vapor removal process.