Adsorption Equilibria and Kinetics for N ₂ on Activated Carbon, Alumina-Zeolite, and Activated Alumina

Nitrogen is widely used as a process gas, as well as a purge gas in industries. In addition, N2 also works as a major impurity associated with adsorption technologies for various off-gases and effluent gases. Therefore, understanding the adsorption characteristics of N2 is of great interest for high-quality gas production. This study examined the adsorption equilibrium and kinetics of three adsorbent pellets, namely activated carbon, alumina-zeolite, and activated alumina, at 293, 308, and 323 K, and pressures up to 1000 kPa. The experimental isotherms were fitted using single-site and dual-site Langmuir models, and the adsorption kinetics were analyzed using experimental uptake curves with a nonisothermal adsorption model with kinetic parameters and diffusional time constant. Activated carbon exhibited a higher adsorption capacity than the other adsorbents. The adsorbents had a fast adsorption rate of N2, showing only a minor difference among the adsorbents. The adsorption characteristics were compared with those of previously reported adsorbents, such as zeolites, activated carbons, and silica gels, to provide insight and practical guidelines for selecting adsorbents when developing adsorption processes.