Fabricating a zeolite membrane on a substrate includes disposing first zeolite crystals on a substrate to yield a first layer on the substrate and disposing second zeolite crystals on the first layer to yield a second layer on the first layer, thereby yielding a membrane precursor. The membrane precursor is heated at a first temperature for a first length of time, and the temperature of the membrane precursor is increased or decreased from the first temperature to a second temperature. The membrane precursor is heated at the second temperature for a second length of time to yield the zeolite membrane. The second zeolite crystals have a smaller average diameter than the first zeolite crystals. The second temperature can exceed the first temperature or the first temperature can exceed the second temperature.

A zeolite membrane complex includes a porous support, and a zeolite membrane formed on the support. The zeolite membrane includes a zeolite crystal phase constituted by a plurality of zeolite crystals, and a dense grain boundary phase, which is a region between the plurality of zeolite crystals. A density of at least part of the grain boundary phase is smaller than a density of the zeolite crystal phase. A width of the grain boundary phase is 2 nm or more and 10 nm or less. Accordingly, it is possible to realize high permeability and high separating performance, and high durability of the zeolite membrane.

Seed crystals are crystals of zeolite to be attached onto a support in production of a zeolite membrane complex including the support and a zeolite membrane formed on the support. The specific surface area of the seed crystals is not smaller than 10 m.sup.2/g and not larger than 150 m.sup.2/g. The strength obtained from a crystal component at a diffraction angle 2θ indicating a maximum peak in a range of diffraction angle 2θ from 12° to 25° in an X-ray diffraction pattern obtained by emitting X-ray to the seed crystals is not less than once and not more than 30 times that obtained from an amorphous component. It is thereby possible to improve adherence of the seed crystals to the support.

A separation membrane complex includes a porous support and a separation membrane formed on the support. The separation membrane has a small void. A small void index I.sub.k expressed by (Σ(S.sub.k.sup.1.5))/(S.sub.m.sup.1.5) and indicating the abundance ratio of small voids is higher than or equal to 10×10.sup.−15, and a large void index I.sub.p expressed by (Σ(S.sub.p.sup.2))/(S.sub.m.sup.2) and indicating the abundance ratio of large voids is lower than 200×10.sup.−22, where S.sub.m is the surface area of the separation membrane, S.sub.k is the area per small void, and S.sub.p is the area per large void. Accordingly, the separation membrane complex can achieve a high separation ratio.

There is provided a membrane comprising: a porous support layer having a first surface and a second surface; a palladium (Pd)-based selective layer on a first surface of the support layer; and a zeolite protective layer on a second surface of the support layer, wherein the support layer is between the Pd-based selective layer and the zeolite protective layer. There is also provided a method of forming the same.

Disclosed herein is an ion selective separation membrane including: a metal organic framework layer formed on, in, and/or around a substrate, the metal organic framework having a crystal structure that includes a first surface and a second surface and includes ion transport channels formed between respective pore windows in the first surface and the second surface; first and second electrodes to apply a potential difference across the membrane; wherein the respective pore windows have a pore size that is less than the hydrated diameter of the ion for which the ion selective separation membrane is selective.

Disclosed are a heterogeneous zeolite membrane and a method of preparing the same, and more particularly a heterogeneous zeolite membrane that has CHA and DDR zeolite structures by growing seed particles into a crystal structure different from that of the zeolite membrane and can thus separate CO.sub.2/N.sub.2 and CO.sub.2/CH.sub.4 even under wet conditions, a method of preparing the same, and a method of capturing and removing carbon dioxide using the membrane.

Provided is a method for separating ammonia gas using zeolite membrane having excellent separation stability at a high temperature capable of separating ammonia gas from a mixed gas composed of multiple components including ammonia gas, hydrogen gas, and nitrogen gas to the permeation side with high selectivity and high permeability. Also provided is a method for separating ammonia by selectively permeating ammonia gas from a mixed gas containing at least ammonia gas, hydrogen gas, and nitrogen gas using a zeolite membrane, wherein the ammonia gas concentration in the mixed gas is 1.0% by volume or more.

Disclosed are a heterogeneous zeolite membrane and a method of preparing the same, and more particularly a heterogeneous zeolite membrane that has CHA and DDR zeolite structures by growing seed particles into a crystal structure different from that of the zeolite membrane and can thus separate CO.sub.2/N.sub.2 and CO.sub.2/CH.sub.4 even under wet conditions, a method of preparing the same, and a method of capturing and removing carbon dioxide using the membrane.

The present invention relates to a separator membrane having a hierarchical structure, a production method therefor and a xylene separation method using same, and to: a separator membrane having a hierarchical structure comprising mesopores, the separator membrane having mesopores introduced inside a microporous zeolite separator membrane, thereby being thin, having less defects and exhibiting high xylene permeation and separation performance; a production method therefor; and a xylene separation method using same.