Use of zeolite filter in portable equipment for recovering SF6 in SF6/N2 mixtures

We propose using zeolite filter in portable processing equipment to separate and recover SF₆ from SF₆/N₂ mixtures. Testing of a prototype filter has shown that SF₆ is completely adsorbed by the filter, and the exhaust gas from the filter is pure N₂ (i.e., at an undetectable level of SF₆ measured by a gas chromatograph). The SF₆ fraction of the sorbate phase (solid phase) has been evaluated from the tests, and it is a high fraction as expected. For example, 70% sorbate corresponding to processing a mixture of 5% SF₆, and 83% sorbate corresponding to processing a mixture containing 10% SF₆. The process of releasing the SF₆ from the filter and renewing the filter by thermal swing adsorption (TSA) technique has also been investigated to determine a commercial operating temperature of 150°C. The feasibility of applying this new concept in a portable SF₆/N₂ mixture processing equipment is discussed and compared with an alternative system that the authors developed previously which was based on pressure swing adsorption (PSA) technique and also using zeolite.