Capturing a Specific Component from Mixed (SF6 + N2) Gasses Using Crystal Structure Change of Hydroquinone

Abstract

During the reaction of the solid and the gas phases, solid hydroquinone (HQ) changes its crystal structure while a specific component from mixed gasses is captured into the changed HQ crystal structure. To investigate the partitioning of mixed gasses in the solid phase, the (SF₆ + N₂) gas mixtures having various compositions are used as a gas phase reactant at two experimental pressures, 2.0 and 4.0 MPa. In addition, spectroscopic measurements are also performed to obtain qualitative and quantitative information on partitioning of each gas component. From a series of experimental results, it was found that N₂ is exclusively accommodated in the gas-loaded HQ crystal structure, while SF₆ is excluded from the solid crystal structure due to its large molecular size. However, because such partitioning requires high partial pressures of N₂ in the gas mixtures (higher N₂ composition at a given pressure or higher experimental pressure at a given gas composition), N₂ capture in the HQ crystal structure is only observed at 80-mol% N₂ composition at the experimental pressure of 4.0 MPa among various gas compositions. The captured amount of N₂ corresponds to 13.7 L at the STP condition per 1 kg of HQ. Although N₂ is found to be selectively separated from the binary gas mixtures, further investigations focusing mainly on the reduction of the experimental pressure and the increase of captured N₂ amount are necessary to apply to industrial fields.