Gas separation asymmetric membrane, gas separation module, gas separation device, and gas separation method

A gas separation asymmetric membrane comprising:

• a porous layer having gas permeability;
• a compact layer having gas separation capability which is formed on the porous layer;
• and
• a siloxane compound layer on the compact layer,
• wherein the gas separation asymmetric membrane is formed using a polyimide compound which has a structural unit represented by Formula (I) and at least one structural unit selected from a structural unit represented by Formula (II) or a structural unit represented by Formula (III) and in which the viscosity, at 25° C., of a solution obtained by dissolving the polyimide compound in N-methylpyrrolidone at a concentration of 5% by mass is in a range of 2.2 to 22.0 mPa·sec,
• in the formula, X1 represents a group having a structure represented by Formula (I-a) or (I-b)
• wherein the siloxane compound layer has a structure represented by Formula (1) and a structure represented by Formula (2) or (3)
• in the formulae, RS represents an alkyl group or an aryl group, LA represents a single bond or a divalent linking group, XA represents a linking group selected from *—O-M1-O—, *—S-M1-S—*, *—O—CH2—O—*, *—S—CH2CH2—*, *—OC(═O)O—*, *—CH2CH2—*, and *—C(═O)O−N+(Rd)3—*, M1 represents Zr, Fe, Zn, B, Al, Ti, In, or Ga, Rd represents a hydrogen atom or an alkyl group, m and n represent an integer of 2 or greater, the symbol * represents a linking site, and the symbol ** represents a linking site in a siloxane bond.