Recent Advances in Advanced Membrane Materials for Natural Gas Purification: A Review of Material Design and Separation Mechanisms

Natural gas plays a pivotal role in the global energy landscape under the dual challenges of energy transition and climate change. However, the impurities present within natural gas pose several disadvantages, including corrosion of transportation pipelines, toxicity, hydrate formation, and a reduction in the fuel's calorific value. Membrane separation technology has been recognized as an ideal approach for natural gas purification owing to its advantages of low energy consumption, operational simplicity, and excellent separation performance. This review summarizes recent progress in the development of advanced membrane materials, including polymer bulk membranes, two-dimensional (2D) nanosheet membranes, mixed-matrix membranes (MMMs), surface-modified membranes, and carbon molecular sieve membranes (CMSMs). The fundamental separation mechanisms-such as solution-diffusion, molecular sieving, adsorption-selectivity, and competitive sorption and surface diffusion-are analyzed in detail. Moreover, the critical scientific questions and technological challenges in this field are discussed in depth. Finally, future research perspectives are proposed to guide the rational design and practical application of high-performance membranes for natural gas separation.