The aminosilanegraftingonmicro-sizednanoporoussodiumzeoliteYparticleswasperformedand novelmixedmatrixmembranes(MMMs)werefabricatedbyembeddingthemodified particlesintothe Matrimids5218matrix.Theaminosilanegraftingreactionwasconsideredusing3-aminopropyl (diethoxy)methylsilane(APDEMS)asthesilanecouplingagent.DLS,BET,XRD,FTIR-ATR,CAM,SEM, and TG/DTGwereinvestigatedtocharacterizethepurezeolite(NaY),silanemodified zeolite(Sm-NaY) and thefabricatedMMMs.Moreover,theeffectsof filler content(0–20 wt%)onpureandmixedgas experiments,feedpressure(2–12bar)andoperatingtemperature(35–75 1C) onCO2/CH4 transport properties ofMatrimid/Sm-NaYweresurveyed.Theobtainedresultsrevealedthatat15wt% filler loading (theoptimumcondition),theCO2 permeability increasedfrom8.34BarrerforMatrimidto 9.70 Barrer(about16%).TherelatedCO2/CH4 selectivitywasconsiderablyincreasedfrom36.3to57.1 (about 57%).Thissuperiorperformanceat15wt% filler loadingwasrelatedtothegooddispersionofthe silane modified NaYparticlesintheMatrimidmatrix.Thedefectfreepolymer/filler interfacewas achieved bytheaminosilanesgraftedontheexternalsurfaceofthezeolites.