Formation Behaviors and Selective Separation of the Binary (SF6+N2) Gas Mixtures Using Hydroquinone Clathrate

Abstract

After reacting hydroquinone (HQ) powder with pure sulfur hexafluoride (SF6) and nitrogen (N2), and binary gas mixtures of (SF6 + N2) with various compositions at experimental pressures of 20 bar and 40 bar, the HQ samples are analyzed using a series of analytic methods to obtain both qualitative and quantitative information. As a result, it was found that N2 can be enclathrated into cavities of the formed HQ clathrate if the simplified partial pressure of N2 is sufficiently large (occupation of 10% per one cavity when the simplified partial pressure is 32 bar, and occupation of 40% per one cavity when the pressure of pure N2 is 40 bar). In addition, additional experiments were performed to evaluate the N2 storage in the clathrate depending on the experimental pressure. When the pressure of pure N2 was increased up to 80 bar, the occupation per one clathrate cage was calculated to be 55%, which corresponded to 18.7 L of N2 at STP conditions per 1 kg of HQ. Because higher pressure is required to form the HQ clathrate and the stored amount of gas molecules is smaller compared with other technologies such as adsorption or hydrate-based process, a lot of additional investigations will be necessary, focusing on reducing energy consumption and increasing the gas storage.