Process for kinetic gas-solid chromatographic separations
AssigneeAir Products and Chemicals, Inc.
InventorsPhilip B. Henderson, Charles G. Coe, Donald E. Fowler, Montford S. Benson
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Abstract
A method is disclosed for the kinetic separation of gas mixtures using gas-solid chromatography. More specifically, a method is disclosed for the kinetically driven gas-solid chromatographic separation of NF.sub.3 from CF.sub.4 in significant volumes over a specific class of adsorbents to recover NF.sub.3 at high purities, such as 99.99% NF.sub.3.
Claims18
A method of recovering a purified first component from a mixture of at least first component and second component using gas-solid chromatography comprising passing discrete pulses of a mixture of the first and second component in a continuous flow of an inert carrier gas through a bed of porous adsorbent that kinetically adsorbs one component more readily than the other component and having an effective pore window sufficient for kinetic differentiation of the components at an appropriate mass velocity for a kinetic separation and separately recovering the first component from the bed as product first component having a reduced content of the second component.
A method for separately recovering NF.sub.3 and/or CF.sub.4 from a mixture of NF.sub.3 and CF.sub.4 comprising passing a mixture of NF.sub.3 and CF.sub.4 in an inert carrier gas through a zone of porous adsorbent, that differentially adsorbs and separates NF.sub.3 from CF.sub.4, having an effective pore window between that of 4A and 5A molecular sieves, at a mass velocity of at least 1.0 g/sq cm-hr and a zone temperature less than approximately 100.degree. C. and separately recovering NF.sub.3 and/or CF.sub.4 from the zone, each having a reduced content of the other component.
A method of recovering purified NF.sub.3 from a mixture of NF.sub.3 and CF.sub.4 using gas-solid chromatography comprising passing discrete pulses of a mixture of NF.sub.3 and CF.sub.4 in a continuous flow of an inert carrier gas through a bed of porous adsorbent that kinetically adsorbs NF.sub.3 more readily than CF.sub.4 selected from the group consisting of hydrothermally pretreated 5A zeolitic molecular sieve and chabazite and having an effective pore window in the range of 4.4 .ANG. to 4.8 .ANG., at a mass velocity of to 2.5 to 8.6 g/sq cm-hr and a zone temperature in the range of 0.degree. to 60.degree. C. and separately recovering the NF.sub.3 from the bed as product NF.sub.3 having a purity of at least 99.99% NF.sub.3.
Dependencies are inferred from the claim text.