Protective-layer-covered gas separation membrane, method for producing protective-layer-covered gas separation membrane, gas separation membrane module, and gas separation apparatus

1. A protective-layer-covered gas separation membrane comprising:

a gas separation membrane including a resin layer containing a compound having a siloxane bond;

a protective layer located on the resin layer; and

a porous layer on the protective layer,

wherein the protective layer includes a region PLi present in the porous layer and a region PLe present on the porous layer, and

a degree of infiltration of the protective layer into the porous layer is 10% to 90%, the degree of infiltration being expressed by the following formula:

degree of infiltration of protective layer into porous layer=100%×(thickness of PLi )/(thickness of PLi +thickness of PLe ),

wherein the porous layer has a carbon dioxide permeability coefficient of 2,000 barrers or more, and

wherein the gas separation membrane satisfies one of conditions 1, 3, and 4:

condition 1: the resin layer satisfies inequalities 1 and 2:

inequality 1: 0.9≥A/B≥0.55

inequality 2: B≥1.7

wherein A represents an O/Si ratio that is a ratio of the number of oxygen atoms to the number of silicon atoms contained in the resin layer at a depth of 10 nm from a surface of the resin layer, and B represents an O/Si ratio that is a ratio of the number of oxygen atoms to the number of silicon atoms in the surface of the resin layer;

condition 3: a minimum percentage Si 0 of Si 2+ and Si 3+ peaks relative to all Si peaks in ESCA depth profiling of the resin layer is 1% to 40%; and

condition 4: a positron lifetime τ3 of a third component formed by implantation of a positron with an energy of 1 keV into the surface of the resin layer is 3.40 to 4.20 ns.

2. The protective-layer-covered gas separation membrane according to claim 1 , wherein the gas separation membrane has a porous support A and the resin layer disposed on the porous support A and satisfies condition 2:

condition 2: the compound having a siloxane bond has a repeating unit represented by general formula (2) and a repeating unit represented by general formula (3):

wherein R 11 represents a substituent, * represents a site linked to # in general formula (2) or (3), and # represents a site linked to * in general formula (2) or (3),

the gas separation membrane includes a region GLi where the compound having a siloxane bond is present in the porous support A and a region GLe where the resin layer is present on the porous support A,

GLe has a thickness of 50 to 1,000 nm,

GLi has a thickness of 20 nm or more, and the thickness of GLi is 10% to 350% of the thickness of GLe, and

a difference between a content of the repeating unit represented by general formula (3) in a surface layer of GLe extending to a depth of 20 nm and a content of the repeating unit represented by general formula (3) in a surface layer of GLi extending to a depth of 20 nm is 30% to 90%.

3. The protective-layer-covered gas separation membrane according to claim 1 , wherein the protective layer contains a silicone resin.

4. The protective-layer-covered gas separation membrane according to claim 2 , wherein the protective layer contains a silicone resin.

5. The protective-layer-covered gas separation membrane according to claim 3 , wherein the silicone resin contains a Si 4+ component.

6. The protective-layer-covered gas separation membrane according to claim 1 , wherein the protective layer has a thickness of 200 to 3,000 nm.

7. The protective-layer-covered gas separation membrane according to claim 1 , wherein the resin layer of the gas separation membrane and the protective layer are adjacent to each other.

8. A method for producing the protective-layer-covered gas separation membrane according to claim 1 , the method comprising:

laminating a layered body of the porous layer and the protective layer to the resin layer of the gas separation membrane.

9. A gas separation membrane module comprising the protective-layer-covered gas separation membrane according to claim 1 .

10. A gas separation apparatus comprising the gas separation membrane module according to claim 9 .