Patent ID: 7041155

Claim:
A nitrogen selective adsorbent comprising a zeolite of a faujasite crystalline structure containing lithium ions and at least one type of cations selected from ammonium ions and protons as essential cations, the nitrogen selective adsorbent having a nitrogen adsorption characteristic represented by the following expression (1) at 760 Torrs at 20° C.: y 1 =ax+b (1) wherein y 1 is the amount of adsorbed nitrogen per unit lattice of a zeolite crystal, x is the number of associated Li + ions per unit lattice of the zeolite crystal, a is a variable calculated from the following equation: a−a ′−0.2 ×√{square root over (z)} (wherein a ′ is 0.30 to 0.40), b is a variable calculated from the following equation: b=b ′+19.2 ×√{square root over (z)} (wherein b ′ is −19.6 to −15.1), and z ⁢ ⁢ is ⁢ ⁢ z = Number ⁢ ⁢ of ⁢ ⁢ moles ⁢ ⁢ of ⁢ ⁢ H + Total ⁢ ⁢ number ⁢ ⁢ of ⁢ ⁢ moles ⁢ ⁢ of ⁢ ⁢ cations ⁢ ⁢ other ⁢ ⁢ than ⁢ ⁢ Li + (wherein z is 0.3 to 1.0).