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Recently, the team led by Professor Lu Anhui, Dean of the School of Chemical Engineering at Dalian University of Technology, synthesized a series of molecular sieve-type nanocarbon sheets with precisely controllable pore sizes, enabling the efficient separation of various mixed gases. The mixing of gases is a thermodynamically spontaneous process. As a reversible process, gas separation requires external work and consumes energy. Therefore, how to reduce energy consumption and achieve efficient gas separation is a current research focus and challenge in the field of separation. Carbonaceous adsorbents are widely used in gas adsorption and separation due to their stable chemical properties, resistance to water vapor, and well-developed pore structure, with the micropore size being a key factor determining their separation performance. However, since the particle size of conventional carbon precursors is usually above the micrometer range, issues of non-uniform mass and heat transfer occur during pyrolysis, resulting in a disordered, turbulent structure with a high sp3 carbon content, which makes it difficult to control the size of the micropores. Furthermore, the common problem with porous carbon frameworks, namely large size of structural units and thick pore walls, which result in long diffusion paths for gas molecules and low utilization efficiency of internal micropores, also needs to be addressed urgently. Based on the temperature-controlled phase transition method, Professor Lu Anhui’s team synthesized molecular sieve-type nanocarbon sheets with precisely controllable pore sizes. These nanocarbon sheets have an SP2 carbon content of over 80%; their micropore sizes can be adjusted accurately within the range of 0.53–0.58 nm, while their thickness can also be controlled precisely within the range of 30–65 nm. When used for gas separation, nanocarbon sheets enable the massive and rapid adsorption of adsorbate molecules at low pressures (<0.1 bar). Under normal temperature and pressure conditions, nanocarbon sheets exhibit high absorption capacities (5.2, 5.3, and 5.1 mmol g-1) and selectivities (7, 71, and 386) for CO2, C2H6, and C3H8, respectively. Furthermore, dynamic penetration experiments simulating the composition of real natural gas further confirmed the advantages of this porous carbon material, namely its high adsorption capacity, good selectivity, easy regeneration, and excellent resistance to water vapor.