Novel SF6 gas concentration method using hydrate-based gas uptake and sweating process

•New gas hydrate-based sweating process described.•The process decomposes gas hydrate under constant pressure with rising temperature.•Single- and multiple-step sweating processes experimentally demonstrated.•SF6 gas was concentrated from 50% to 90% by a multistep sweating operation. Hydrate-based gas separation is a method of separating gas mixtures into their individual components using their differences in thermodynamic properties. The maximum concentration of the target gas is equilibrium-constrained when using a single stage of operation. In this study, we propose a novel hydrate-based gas uptake and sweating process under constant pressure with rising temperature. We theoretically calculated the SF6–N2 gas hydrate pressure–temperature and pressure–gas composition equilibrium conditions to determine operating conditions for the process. Verification experiments conducted below 1 MPa and below 283 K revealed that SF6 was concentrated up to 90 % using this process in a multistep operation.