Adsorption of nitrogen and oxygen in cobalt (II)-exchanged zeolite A

The cobalt (II)-exchanged zeolite A (NaCoA) was prepared by cation exchange process with zeolite A (NaA) and Co(NO3)2 in aqueous solution. A static volumetric system was employed to evaluate the N2 and O2 adsorption properties of NaCoA at 298 K. It was found that the N2 adsorption capacity of NaCoA increased rapidly with the rising pressure, and the adsorption isotherm of N2 became nonlinear in low pressure region. The O2 adsorption capacity of NaCoA increased slightly with pressure. The introduction of Co2+ into the NaA enhanced the N2 adsorption capacity and N2/O2 selectivity, which could be contributed to the π-complexation between N2 and Co2+. This strong interaction brought about a series of high value for Henryʹs constant, Langmuir constant, adsorption selectivity and adsorption capacity of N2 in NaCoA. Infrared spectra were also carried out to illustrate that the N2 were bonding with Co2+.