Use of zeolite filter in portable equipment for recovering SF/sub 6/ in SF/sub 6//N/sub 2/ mixtures

We propose using zeolite filter in portable processing equipment to separate and recover SF/sub 6/ from SF/sub 6//N/sub 2/ mixtures. Testing of a prototype filter has shown that SF/sub 6/ is completely adsorbed by the filter, and the exhaust gas from the filter is pure N/sub 2/ (i.e., at an undetectable level of SF/sub 6/ measured by a gas chromatograph). The SF/sub 6/ 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% SF/sub 6/, and 83% sorbate corresponding to processing a mixture containing 10% SF/sub 6/. The process of releasing the SF/sub 6/ 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/spl deg/C. The feasibility of applying this new concept in a portable SF/sub 6//N/sub 2/ 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.