Carbon molecular sieve

Carbon molecular sieves are essentially a type of activated carbon. What sets them apart from ordinary carbon-based adsorbents is that the pore sizes of their micropores are uniformly distributed within a narrow range; these pore sizes are comparable to the diameter of the gas molecules to be separated. The specific surface area of these micropores accounts for over 90% of the total surface area of the carbon molecular sieve. The pore structure of carbon molecular sieves is mainly organized as follows: large pores have diameters that connect to the outer surface of the carbon particles; transitional pores branch off from the large pores; and micropores branch off from the transitional pores. During the separation process, the macropores primarily serve as transport channels, while the micropores act as molecular sieves. The methods for producing carbon molecular sieves from coal as a raw material include carbonization, gas activation, carbon deposition, and impregnation. Among them, the carbonization method is the simplest, but to produce high-quality carbon molecular sieves, these methods must be used in combination. Carbon molecular sieves have achieved success in the production of nitrogen through air separation, and they also hold great potential for other gas separation applications. ----------Source: http://bbs.hcbbs.com/viewthread.php?tid=428654

Regarding pressure swing adsorption nitrogen production systems, the mainstream approach in China involves using foreign-made carbon molecular sieves as adsorbents, with a dual-tower configuration. At an adsorption pressure of 0.6–0.8 Mpa, nitrogen is extracted through nitrogen flushing and vacuum desorption processes. This setup results in low energy consumption, around 0.3–0.4 Nm3/kWh. Recent research on carbon molecular sieves focuses on adding iron oxide to them, thereby enhancing their selective adsorption of oxygen due to its magnetic properties. There are written reports from Japan, and Dalian University of Technology has also conducted research in this area. It is highly likely that in the future, pressure swing adsorption technology will enable the production of nitrogen with a purity of over 99.999%. As for current nitrogen production technologies, carbon molecular sieve technology is the dominant one, while zeolite molecular sieve technology is less used because of the complex steps involved such as treating raw gas and performing vacuum desorption. Although zeolite molecular sieve technology can produce high-purity nitrogen, it requires high energy consumption, and the scale of production is typically below 200 Nm3. High-purity nitrogen is generally produced using hydrogenation deoxygenation technology: an appropriate amount of hydrogen is added to ordinary nitrogen, and under the action of a hydrogenation deoxygenation catalyst, hydrogen reacts with oxygen to form water. The remaining hydrogen or oxygen is then removed, and finally, moisture is eliminated through a drying tower to obtain high-purity nitrogen. Source: http://bbs.hcbbs.com/viewthread.php?tid=269421

So do you know what the adsorption principle is at the surface of the micropores, which are responsible for the adsorption function in carbon molecular sieves? What is its surface structure like as well?