Integrated gas hydrate-membrane system for natural gas purification

Significant efforts are being made to make natural gas processing energy-efficient and environmentally friendly by utilizing membrane based separation processes. While membranes (polymer/zeolite/metal-organic framework) are effective in separating CO2 and N2 from CH4, their separation performance is negatively affected when natural gas contains high concentrations of higher hydrocarbons (propane, butane, etc.) and H2S. Interestingly, higher hydrocarbons and H2S form gas (clathrate) hydrates at much milder conditions compared to CH4, CO2, and N2 and could thus act as a separation step before membranes. In this perspective, gas separation using membranes and gas hydrates is briefly reviewed, and the challenges of developing an integrated gas hydrate-membrane process are discussed. Such a process could be an energy efficient approach to reduce the costs associated with natural gas purification. The proposed system can also serve as a model for other challenging molecular gas separations relevant to the energy and environmental arenas, including flue gas treatment and hydrogen purification.