Gas separation membrane, method of producing gas separation membrane, gas separation membrane module, and gas separator
Provided are a gas separation membrane which has a resin layer containing a compound having a siloxane bond, in which the resin layer containing a compound having a siloxane bond satisfies Expressions 1 and 2, and at least one of gas permeability or gas separation selectivity is high under high pressure; a method of producing a gas separation membrane; a gas separation membrane module; and a gas separator. 0.9≥ A/B ≥0.55 Expression 1 B ≥1.7 Expression 2 In the expressions, A represents an O/Si ratio that is a ratio of the number of oxygen atoms relative to the number of silicon atoms contained in the resin layer containing a compound having a siloxane bond at a depth of 10 nm from the surface of the resin layer containing a compound having a siloxane bond, and B represents an O/Si ratio that is a ratio of the number of oxygen atoms relative to the number of silicon atoms in the surface of the resin layer containing a compound having a siloxane bond.
1. A gas separation membrane which satisfies any one of the following Conditions 1, 3, and 4,
Condition 1: a gas separation membrane which has a resin layer containing a compound having a siloxane bond, in which the resin layer containing a compound having a siloxane bond satisfies the following Expressions 1 and 2,
0.9≥ A/B≥ 0.55, and Expression 1
B≥ 1.7 Expression 2
in Expressions 1 and 2, A represents an O/Si ratio that is a ratio of the number of oxygen atoms relative to the number of silicon atoms contained in the resin layer containing a compound having a siloxane bond at a depth of 10 nm from the surface of the resin layer containing a compound having a siloxane bond, and B represents an O/Si ratio that is a ratio of the number of oxygen atoms relative to the number of silicon atoms in the surface of the resin layer containing a compound having a siloxane bond,
Condition 3: a gas separation membrane which has a resin layer containing a compound having a siloxane bond, in which a minimum value Si 0 of the proportion of peaks of Si 2+ and Si 3+ to peaks of all Si in ESCA depth analysis of the resin layer containing a compound having a siloxane bond is in a range of 1% to 40%, and
Condition 4: a gas separation membrane which has a resin layer containing a compound having a siloxane bond, in which positron lifetime τ3 of a third component in a case where the positron is implanted at a strength of 1 keV from the surface of the resin layer containing a compound having a siloxane bond is in a range of 3.40 to 4.20 ns,
and which further comprises a porous support A and satisfies the following Condition 2,
Condition 2: a gas separation membrane which includes a porous support A; and a resin layer containing a compound having a siloxane bond positioned on the porous support A,
wherein the compound having a siloxane bond includes at least a repeating unit represented by the following Formula (2) or a repeating unit represented by the following Formula (3),
the resin layer containing a compound having a siloxane bond includes a region GLi present in the porous support B and a region GLe present on the porous support B,
the thickness of GLe is in a range of 50 to 1,000 nm,
the thickness of GLi is 20 nm or greater and the thickness of GLe is in a range of 10% to 350%, and
a difference between the content of the repeating unit represented by Formula (3) described above in 20 nm of the GLe surface layer and the content of the repeating unit represented by Formula (3) described above in 20 nm of the GLi surface layer is in a range of 30% to 90%,
in Formulae (2) and (3) described above, R 11 represents a substituent, the symbol “*” represents a binding site with respect to # in Formula (2) or (3) described above, and the symbol “#” represents a binding site with respect to * in Formula (2) or (3) described above.
2. The gas separation membrane according to claim 1 ,
wherein the thickness of GLe is in a range of 200 to 900 nm.
3. The gas separation membrane according to claim 1 ,
wherein the thickness of GLi is 20% to 90% of the thickness of GLe.