Abstract: A nitrogen selective adsorbent comprises a zeolite of a faujasite crystalline structure containing Li+ and at least one of NH+ and H+ as essential cations, and has a nitrogen adsorption characteristic represented by specific correlation between the number of associated Li+ ions per unit lattice of a zeolite crystal and the amount of adsorbed nitrogen per unit lattice of the zeolite crystal. An air separation method employs the aforesaid nitrogen selective adsorbent for separation between nitrogen and oxygen by selective adsorption of nitrogen in air.

Abstract: A nitrogen selective adsorbent comprises a zeolite of a faujasite crystalline structure containing Li+ and at least one of NH+ and H+ as essential cations, and has a nitrogen adsorption characteristic represented by specific correlation between the number of associated Li+ ions per unit lattice of a zeolite crystal and the amount of adsorbed nitrogen per unit lattice of the zeolite crystal. An air separation method employs the aforesaid nitrogen selective adsorbent for separation between nitrogen and oxygen by selective adsorption of nitrogen in air.

Abstract: A nitrogen adsorbent comprising a crystalline X zeolite having a faujasite structure with an SiO2/Al2O3 ratio of less than 3.0, wherein the crystal contains at least one trivalent element of the group consisting of Fe, B and Ga and (AlO4)5− tetrahedral units thereof associated with cations. Although the adsorbent contains a designated trivalent element in the zeolite, it maintains the number of cation sites contributing to adsorption, has an excellent separation performance of nitrogen and oxygen, and exhibits excellent heat resistance. Further, when the nitrogen adsorbent of the present invention is used in such a particular manner that it adsorbs nitrogen after being heated under a vacuum, adsorption performance is improved.