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Minimization of energy consumption was explored for countercurrent switched cryogenic packed beds in which separation of CO2 and other components of natural gas can be achieved based on differences in freezing or desublimation points. Highly pure CO2 and methane were obtained after separation. An experimental setup for CO2 removal from natural gas was constructed and a detailed experimental study was conducted by changing different operating parameters. Compared to other cocurrent or jacket‐cooled constant‐temperature configurations, countercurrent switched beds provided optimal separation and energy efficiencies. The effects of important process parameters like initial temperature profiles of the cryogenic bed, feed composition, and feed flow rate on energy requirement, bed saturation, bed pressure, and cycling times were investigated. The energy requirement for cryogenic packed beds was compared with the conventional cryogenic distillation process.

The mixed‐matrix membrane (MMM), a state‐of‐the‐art polymer‐inorganic hybrid, is a relatively recent addition to the membrane family which adopts the synergistic advantages of the polymer and inorganic phase. Although marked improvement has been achieved by MMMs in CO2/CH4 separation, the development of a defect‐free structure to transcend the Robeson upper bound limit remains a challenge. In previous years, a number of inorganic materials with diverse nature have been studied for CO2/CH4 separation; however, layered silicates have not attracted much attention despite their superior thermal and mechanical properties. Analyses of the potential of using layered silicates as inorganic fillers in MMM fabrication for CO2/CH4 separation are reviewed. Additionally, the immediate challenges toward successful formation of layered silicate‐based MMM and future prospects are addressed.

Sonochemical-assisted method has been identified as one of the potential pre-treatment methods which could reduce the formation duration of zeolite as well as other microporous and mesoporous materials. In the present work, zeolite T was synthesized via sonochemical-assisted pre-treatment prior to hydrothermal growth. The durations for sonochemical-assisted pre-treatment were varied from 30min to 90min. Meanwhile, the hydrothermal growth durations were ranged from 0.5 to 3days. The physicochemical properties of the resulting samples were characterized using XRD, FESEM, FTIR and BET. As verified by XRD, the samples synthesized via hydrothermal growth durations of 1, 2 and 3days and sonochemical-assisted pre-treatment durations of 60min and 90min demonstrated zeolite T structure. The samples which underwent sonochemical-assisted pre-treatment duration of 60min yielded higher crystallinity with negligible change of zeolite T morphology. Overall, the lengthy synthesis duration of zeolite T has been successfully reduced from 7days to 1day by applying sonochemical-assisted pre-treatment of 60min, while synthesis duration of 0.5days via sonochemical-assisted pre-treatment of 60min was not sufficient to produce zeolite T structure.

A comprehensive overview of membrane technology used for natural gas purification and other gas separation applications including methods, materials, and results described in previous studies is presented. Different membrane categories are elaborated thoroughly followed by comparisons made between glassy and rubbery polymeric membranes. Various approaches to improve membrane separation performance, such as incorporation of inorganic fillers and blending technique, are discussed. Gas separation in different membranes, e.g., glassy/rubbery polymer blend membranes, mixed matrix membranes, and polymeric blend mixed matrix membranes, are considered. Adopted techniques by researchers to solve existing issues in membrane fabrication and performance are explained in detail.

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