The present disclosure is directed to a potassium-form MER framework type zeolite, a MER framework type zeolite having a stick-like morphology, wherein the potassium is present as K.sup.+ in extra-framework locations. The zeolite is essentially free of an extra-framework cation other than potassium.

A zeolite membrane complex includes a porous support and a zeolite membrane formed on the support. Water molecules are adsorbed in the zeolite membrane. A decreasing rate of water content in the zeolite membrane from 250° C. to 500° C. is 0.1% or more.

In production of a zeolite membrane complex, a starting material solution containing at least a structure-directing agent and FAU-type zeolite particles having an average particle diameter of 50 to 500 nm is prepared. Then, a support is immersed in the starting material solution to form a zeolite membrane on the support by hydrothermal synthesis, the zeolite membrane being composed of AFX-type zeolite. After that, the structure-directing agent in the zeolite membrane is removed.

A method of producing a separation membrane includes a seed crystal adhesion step of adhering zeolite seed crystals to a porous support formed of stainless steel to obtain a seed crystal-bearing support and a separation layer formation step of forming a porous separation layer formed of a zeolite on the seed crystal-bearing support. The stainless steel has a contact angle with water of 90° or more. The seed crystal adhesion step includes bringing the zeolite seed crystals and a solvent having a contact angle with the stainless steel of 30° or less into contact with the porous support.

A zeolite membrane composite includes a porous support and a zeolite membrane formed on at least one surface of the porous support. The zeolite membrane of the zeolite membrane composite is formed of an X-MOR-type zeolite, where X includes at least one type of transition metal ion.

A separation method includes a separation step of using a zeolite membrane composite to separate a branched diolefin from a branched hydrocarbon mixture containing the branched diolefin and at least one branched hydrocarbon in which the number of carbon-carbon double bonds is 1 or less and that is of an equivalent carbon number n to the branched diolefin. The zeolite membrane composite used in this step is a zeolite membrane composite that includes a porous support and a FAU-type zeolite membrane formed on at least one surface of the porous support, and in which the FAU-type zeolite membrane is a silylated FAU-type zeolite membrane including a silyl group at the surface thereof.

Disclosed are a MWW/DDR type gas separation membrane comprising at least one MWW type zeolite and at least one DDR type zeolite and a method for preparing the same. One of the MWW type zeolite and the DDR type zeolite is disposed on the other thereof, wherein at least one of the MWW type zeolite and the DDR type zeolite is epitaxially grown. In the gas separation membrane, the DDR type zeolite is epitaxially grown from the MWW type zeolite, or the MWW type zeolite is epitaxially grown from the DDR type zeolite. Thus, the MWW/DDR type gas separation membrane is synthesized using a structural continuity of the MWW type zeolite and the DDR type zeolite. Thus, the gas separation membrane has excellent separation efficiency.

In a method for preparing a zeolite CHA membrane, a gel conversion method is adopted to assist crystallization, seed solutions with different concentrations and sizes are successively coated on the surface of a porous support to obtain a seed layer, a synthetic gel is coated on the seed layer to obtain a gel layer, and then the porous support is subjected to a membrane crystallization reaction to obtain a zeolite CHA membrane. The method skips the conventional stage of converting the heterogeneous zeolite into the zeolite CHA seed, and directly takes a heterogeneous zeolite with the same secondary structural unit as that of zeolite CHA as a seed to directly prepare a zeolite CHA membrane on a support.

Composite structures composed of inorganic membranes or polymer membranes supported on a multilayered woven wire mesh substrate are provided. Also provided are methods of making the composite structures and methods of using the composite structures as separation membranes. The mesh substrates are composed of a stack of two or more layers of woven wire mesh, wherein the different mesh layers in the stack have different mesh sizes. The multilayered mesh structure can support a defect-free, or substantially defect-free, membrane and has sufficient mechanical strength to allow the supported membranes to be used for chemical separations.

A peak intensity of a (002) plane is greater than or equal to 0.5 times a peak intensity of a (100) plane in an X-ray diffraction pattern obtained by irradiation of X-rays to a membrane surface of the ERI membrane.