Capture of trifluoromethane using ionic liquids

A method for capturing trifluoromethane from a gaseous mixture comprising the step of:

• contacting the gaseous mixture with at least one ionic liquid at a pressure of about 0.1 MPa to about 4.8 MPa and a temperature of about 273 K to about 323 K for a period of time sufficient for the ionic liquid to absorb at least a portion of the trfluoromethane;
• wherein:
• (a) the gaseous mixture is a vent stream from a chlorodifluoromethane manufacturing process, said gaseous mixture consisting essentially of trifluoromethane and nitrogen, oxygen, argon, and/or carbon dioxide;
• and
• (b) the ionic liquid comprises a cation and a fluorinated anion, said cation is selected from the group consisting of cations represented by the structures of the following formulae:
• wherein:
• (I) R1, R2, R3, R4, R5, R6, and R12 are independently selected from the group consisting of:
• (i) H,
• (ii) halogen,
• (iii) —CH3, —C2H5, or C1 to C25 straight-chain, branched or cyclic alkane or alkene, optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH2 and SH;
• (iv) —CH3, —C2H5, or C1 to C25 straight-chain, branched or cyclic alkane or alkene comprising one to three heteroatoms selected from the group consisting of O, N, Si and S, and optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH2 and SH;
• (v) C6 to C20 unsubstituted aryl, or C1 to C25 unsubstituted heteroaryl having one to three heteroatoms independently selected from the group consisting of O, N, Si and S;
• (vi) C6 to C25 substituted aryl, or C1 to C25 substituted heteroaryl having one to three heteroatoms independently selected from the group consisting of O, N, Si and S;
• and wherein said substituted aryl or substituted heteroaryl has one to three substituents independently selected from the group consisting of:
• (A) —CH3, —C2H5, or C1 to C25 straight-chain, branched or cyclic alkane or alkene, optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH2 and SH,
• (B) OH,
• (C) NH2, and
• (D) SH;
• and
• (vii) —(CH2)nSi(CH2)mCH3, —(CH2)nSi(CH3)3, or —(CH2)nOSi(CH3)m, where n is independently 1-4 and m is independently 0-4;
• (II) R7, R8, R9, and R1° are independently selected from the group consisting of:
• (ix) —CH3, —C2H5, or C1 to C25 straight-chain, branched or cyclic alkane or alkene, optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH2 and SH;
• (x) —CH3, —C2H5, or C1 to C25 straight-chain, branched or cyclic alkane or alkene comprising one to three heteroatoms selected from the group consisting of O, N, Si and S, and optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH2 and SH;
• (xi) C6 to C25 unsubstituted aryl, or C1 to C25 unsubstituted heteroaryl having one to three heteroatoms independently selected from the group consisting of O, N, Si and S;
• and C6 to C25 substituted aryl, or C3 to C25 substituted heteroaryl having one to three heteroatoms independently selected from the group consisting of O, N, Si and S;
• and wherein said substituted aryl or substituted heteroaryl has one to three substituents independently selected from the group consisting of:
• (E) —CH3, —C2H5, or C1 to C25 straight-chain, branched or cyclic alkane or alkene, optionally substituted with at least one member selected from the group consisting of Cl, Br, F, I, OH, NH2 and SH,
• (F) OH,
• (G) NH2, and
• (H) SH;
• and
• (xii) —(CH2)nSi(CH2)mCH3, —(CH2)nSi(CH3)3, or —(CH2)nOSi(CH3)m, where n is independently 1-4 and m is independently 0-4;
• and
• (III) optionally at least two of R1, R2, R3, R4, R5, R6, R7, R8, R9, and R10 can together form a cyclic or bicyclic alkanyl or alkenyl group.