Health & Environmental Research Online (HERO)


Print Feedback Export to File
6181310 
Journal Article 
Clinoptilolites for nitrogen/methane separation 
Chinn, D; Hernandez-Maldonado, AJ; Jayaraman, A; Mohr, DH; Munson, CL; Yang, RT 
2004 
Yes 
Chemical Engineering Science
ISSN: 0009-2509 
59 
12 
2407-2417 
Clinoptilolites, naturally occurring zeolites, currently used by nuclear industry for ion exchange and drying, were evaluated for the nitrogen/methane separation. Ion exchange of purified clinoptilolite was carried out individually with the cations Na+, Mg2+, Ca2+, K+ and H+, and the adsorption isotherms and diffusion rates were measured. Purified and Mg-clinoptilolite show potential for nitrogen/methane separation and high-pressure adsorption isotherms were measured in a differential absorption bed. Pressure swing adsorption simulations were performed for purified clinoptilolite, Mg-clinoptilolite and the commercial sorbent ETS-4. Purified clinoptilolite shows slightly higher recovery and lower productivity than ETS-4 for similar product purity (∼95%). Mixed ion-exchanged clinoptilolites of Mg/Ca cations, K/Na cations and Mg/Na cations were also prepared and studied for the nitrogen/methane separation. Mg/Na (50/50) mixed ion-exchanged clinoptilolite exhibits very good equilibrium and kinetic selectivity in the low-pressure range, better than purified clinoptilolite. Mixed-exchange clinoptilolites were also found to show a wide range of adsorption characteristics with varying ratios of cation exchange, thereby making them suitable for further improvements in nitrogen/methane separation. 
Clinoptilolite; Purified clinoptilolite; Ion-exchanged clinoptilolite; Mixed ion exchange; Nitrogen/methane separation; PSA simulation