Combining gas hydrate crystallization and membrane technology: A synergistic approach to natural gas separation

•Gas hydrate method modified with membrane technology to add one more driving force for better natural gas separation.•Methane consist natural gas changed from 75 mol.% to 88 mol.%.•Using the combined method, the methane content in natural gas increased by 13% compared to the gas hydrate method.•Gas hydrate-membrane method allows to get three flows enriched different components. This study aims to extend the investigation of natural gas separation using gas hydrates. This work presents a mathematical modeling and experimental study on gas separation using gas hydrate-membrane crystallization. A membrane module was added to the gas hydrate 4 l crystallization reactor, which was used to provide an additional driving force for separation. Inlet mixture separated to the three flows enriched by different gas components. A mixture is approximating natural gas with the following composition was used: CH4 (75.68 mol.%) - С2H6 (7.41 mol.%) - C3H8 (4.53 mol.%) - n-C4H10 (2.47 mol.%) - CO2 (5.40 mol.%) - H2S (1.39 mol.%) - N2 (3.01 mol.%) - Xe (0.11 mol.%). The process was carried out in a single mass transfer apparatus. The obtained data was compared to mathematical calculation and to results of continuous gas hydrate crystallization without a membrane, presented in our previous work. Experimentally it was found that the combined method allows for 20% more efficient concentration of xenon in the gas hydrate phase compared to the method without a membrane module. Its content in gas mixture increased from 0.440 mol.% to 0.609 mol.% at stage cut θ=0.65. H₂S and CO₂ are the primary components permeable through the membrane. So, CO2 content in gas hydrate phase decreased by 55%. The methane content in the gas phase reached 88% purity in a single cycle of gas hydrate-membrane crystallization at the same stage cut value. As a result of the addition of the membrane module to the system, hydrogen sulfide recovery decreased by 19–36% and xenon recovery increased by 25%. [Display omitted]