NOVELTY - An inorganic microporous supported membrane comprises: (a) a macroporous support; (b) a templated porous intermediate layer coating the support; and (c) a microporous layer coating the templated porous intermediate layer such that the microporous layer is capable of molecular sieving.    USE - The membrane is capable of molecular sieving and finds its use in e.g. purification of sub-quality natural gas, removal of NOx from power-plant flue gas, reduction of greenhouse gases (e.g. CO2) and hydrogen recovery from processing gases or hydrogen purification for fuel-cell applications. The highly selective top layer will, for example, remove N2 and CO2 efficiently from natural gas without suffering from CO2 plasticization commonly seen in dense polymeric membranes or purify H2 from reformate for fuel-cell applications.    ADVANTAGE - The membrane has a precise pore size to achieve molecular sieving with maximized flux and selectivity. The dual-layer approach creates a thin, defect-free (i.e. is free of e.g. cracks and pinholes) microporous membrane that also allows both higher selectivity and higher flux than achieved by the corresponding single-layer microporous membrane.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (A) an inorganic microporous supported membrane, which comprises:    (a) a porous substrate;    (b) a first inorganic porous membrane coating the substrate having an average pore size of less than 25 Angstroms; and    (c) a second inorganic porous membrane, coating the first inorganic membrane, having an average pore size of less than 6 Angstroms;    (B) a method (I) for producing an inorganic dual-layered microporous supported membrane, which comprises:    (a) contacting a porous substrate with a surfactant-template polymeric sol resulting in a surfactant sol coated membrane support;    (b) drying the surfactant sol coated membrane support producing a surfactant-templated polymeric coated substrate;    (c) calcining the surfactant-templated polymeric coated substrate to produce an intermediate layer surfactant membrane;    (d) contacting the intermediate layer surfactant templated membrane with a second polymeric sol producing a polymeric sol coated substrate; and    (e) drying the polymeric sol coated substrate producing an inorganic polymeric coated substrate; and    (f) calcining the inorganic polymeric coated substrate;    (C) a method (II) for producing a supported membrane capable of molecular sieving, which comprises:    (a) preventing a subsequently deposited top microporous sol from penetrating further into the support by modifying a surface of the support; and    (b) depositing the top microporous membrane on a modified support producing the supported membrane capable of molecular sieving.    DESCRIPTION OF DRAWING(S) - The figure shows the scanning electron microscope cross-sectional electron micrograph of dual-layer inorganic supported membrane and the transmission electron microscope micrograph of cross-sectional view of dual-layer inorganic microporous supported membrane.