TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Particles: The molecular sieve particles have maximum diameter, and thin dense selective mixed matrix top layer is thicker than maximum diameter. The molecular sieve is chosen from microporous molecular sieve, mesoporous molecular sieve, carbon molecular sieve and porous metal-organic framework. The microporous molecular sieves are small pore microporous molecular sieves chosen from SAPO-34, Si-DDR, UZM-9, AlPO-14, AlPO-34, AlPO-17, AlPO-53, SSZ-62, SSZ-13, AlPO-18, UZM-25, ERS-12, CDS-1, MCM-65, MCM-47, 4A, 5A, UZM-5, UZM-9, SAPO-44, SAPO-47, SAPO-17, CVX-7, SAPO-35, SAPO-56, AlPO-52, SAPO-43 and medium pore microporous molecular sieve silicalite-1, or large pore microporous molecular sieves chosen from NaX, NaY, KY and/or CaY.    TECHNOLOGY FOCUS - POLYMERS - Preferred Method: Another secondary polymer is dissolved in molecular sieve slurry to functionalize surface of molecular sieve particles. The coating is added to top surface of asymmetric hollow fiber mixed matrix membrane. Preferred Composition: The coating comprises polysiloxane, fluoropolymer, thermally curable silicone rubber and ultraviolet radiation curable silicone polymer. The secondary polymer is chosen from polyethersulfone, sulfonated polyethersulfone, hydroxyl group-terminated poly(ethylene oxide), amino group-terminated poly(ethylene oxide), isocyanate group-terminated poly(ethylene oxide), poly(esteramide-diisocyanate), hydroxyl group-terminated poly(propylene oxide), hydroxyl group-terminated co-block-poly(ethylene oxide)-poly(propylene oxide), hydroxyl group-terminated tri-block-poly(propylene oxide)-block-poly(ethylene oxide)-block-poly(propylene oxide), tri-block-poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) bis(2-aminopropyl ether), polyether ketone, poly(ethylene imine), poly(amidoamine), poly(vinyl alcohol), poly(allyl amine), poly(vinyl amine), and cellulosic polymer, preferably polyethersulfone. The cellulosic polymer is chosen from cellulose acetate, cellulose triacetate, cellulose acetate-butyrate, cellulose propionate, ethyl cellulose, methyl cellulose, and nitrocellulose. The polymer for continuous polymer matrix is chosen from polysulfone, polyetherimide, polyamide, polyimide, polyamide/imide, polyether ketone, poly(ether ether ketone), poly(arylene oxides), poly(esteramide-diisocyanate), polyurethane, poly(benzobenzimidazole), polyhydrazide, polyoxadiazole, polytriazole, poly(benzimidazole), polycarbodiimide, polybenzoxazole, polyphosphazene, microporous polymer, cellulose acetate, cellulose triacetate, poly(3,3',4,4'-benzophenone tetracarboxylic dianhydride-pyromellitic dianhydride-3,3',5,5'-tetramethyl-4,4'-methylene dianiline), poly(3,3',4,4'-benzophenone tetracarboxylic dianhydride-pyromellitic dianhydride-4,4'-oxydiphthalic anhydride-3,3',5,5'-tetramethyl-4,4'-methylene dianiline), poly(3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride-3,3',5,5'-tetramethyl-4,4'-methylene dianiline), poly(3,3',4,4'-benzophenone tetracarboxylic dianhydride-3,3',5,5'-tetramethyl-4,4'-methylene dianiline), poly(3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride-pyromellitic dianhydride-3,3',5,5'-tetramethyl-4,4'-methylene dianiline), poly(2,2'-bis-(3,4-dicarboxyphenyl)hexafluoropropane dianhydride-1,3-phenylenediamine), poly(2,2'-bis-(3,4-dicarboxyphenyl)hexafluoropropane dianhydride-1,3-phenylenediamine-3,5-diaminobenzoic acid), poly(2,2'-bis-(3,4-dicarboxyphenyl)hexafluoropropane dianhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane), poly(benzimidazole), polybenzoxazole and microporous polymer, preferably polyimide, polyetherimide, polyamide, cellulose acetate, cellulose triacetate, polybenzoxazole and microporous polymer.