Study of CO2 and N2 sorption into ZIF-8 at high pressure and different temperatures

Abstract

Worldwide consumption of natural gas (NG) has increased in recent years due to newly discovered reserves and greater energy demand. However, the oil and gas industry has encountered significant challenges regarding the capacity to store and process NG to remove impurities, mainly CO2, in order to avoid corrosion and gas hydrate formation. Thus, it is necessary to optimize the separation process in high-pressure adsorption columns by choosing more selective adsorbents with both high chemical and mechanical stabilities. To make this possible, metal-organic frameworks (MOFs) arise as potential materials due to their high surface area and selectivity. However, there must be a better understanding of the physicochemical stability of these materials under high pressure in relation to structural, thermal, and chemical changes. In this sense, this study evaluates the stability of MOF (ZIF-8) using CO2 and N2 as the sorption gas in a high-pressure equilibrium cell. The X-ray diffraction data show that all ZIF-8 samples are highly crystalline. The samples treated at 20 ​°C show insignificant surface area changes, while an expressive reduction in these areas occurs when treated at 60 ​°C. All samples showed thermal stability under high pressure. Fourier transform infrared spectroscopy, and scanning electron microscopy analyses showed no chemical and morphological changes in the ZIF-8 before and after being submitted to CO2 and N2 sorption at high pressure.