Carbon Molecular Sieve

Carbon Molecular Sieve (CMS), as shown in the figure on the right, is a novel adsorbent developed in the 1970s and is an excellent non-polar carbon material. Its primary component is elemental carbon, and it appears as a black cylindrical solid. Internally, it contains a large number of micropores with diameters ranging from 0.28 to 0.36 nm, along with a small number of macropores and mesopores (also known as transitional pores). As illustrated in the figure below, the specific surface area of these micropores accounts for over 90% of the total pore surface area of the carbon molecular sieve, with the micropore specific surface area generally exceeding 1000 m²/g. The ability of Carbon Molecular Sieve (CMS) for nitrogen production to separate air depends on the different diffusion rates of oxygen and nitrogen in the micropores of the CMS. Due to the differences in the relative diffusion rates of gas molecules with varying kinetic diameters, the components of gas mixtures can be effectively separated. The internal micropore distribution of commonly used carbon molecular sieves should be within the range of 0.28 to 0.36 nm. Within this micropore size range, oxygen (with a kinetic diameter of 0.346 nm) can rapidly diffuse through the micropore openings into the pores, while nitrogen (with a kinetic diameter of 0.364 nm) has difficulty passing through the micropore openings, thereby achieving oxygen-nitrogen separation. Carbon dioxide (with a kinetic diameter of 0.33 nm) can also quickly diffuse through the micropore openings into the pores and is a strongly adsorbed gas.