In a first aspect, the present disclosure relates to a method for forming a diamond membrane, comprising: providing a substrate having an amorphous dielectric layer thereon, the amorphous dielectric layer comprising an exposed surface, the exposed surface having an isoelectric point of less than 7, preferably at most 6; seeding diamond nanoparticles onto the exposed surface; growing a diamond layer from the seeded diamond nanoparticles; and removing a portion of the substrate from underneath the diamond layer, the removed portion extending at least up to the amorphous dielectric layer, thereby forming the diamond membrane over the removed portion.

An object of the present invention is to provide a porous support-zeolite membrane composite ensuring that at the time of separation or concentration with a zeolite membrane, both sufficient throughput and high separation performance are achieved in practice and the present invention relates to a porous support-zeolite membrane composite having a porous support and a zeolite membrane formed on the porous support, wherein part of the zeolite membrane penetrates into the inside of the porous support and the distance from the surface of the porous support to the inside into which the zeolite film penetrates is 5.0 m or less on average.

The invention relates to a high-strength hollow fiber zeolite membrane and its preparation method, characterized in that the support of the high-strength zeolite membrane has a multi-channel hollow fiber configuration. The preparation method comprises first preparing a crystal seed solution, then immersing the dry support with the multi-channel hollow fiber configuration in the crystal seed solution, and extracting and drying the support to obtain a crystal-seeded support; and finally placing the crystal-seeded support in a zeolite membrane synthetic fluid, performing hydrothermal synthesis, and taking out, washing and drying the product to obtain the high-strength hollow fiber zeolite membrane. The multi-channel hollow fiber support can provide high mechanical property, which greatly reduces the depreciation rate of the hollow fiber zeolite membrane equipment during use. Meanwhile, the multi-channel hollow fiber zeolite membrane prepared by the Invention possesses high loading density of permeation flux and membrane module and can reduce the production cost and improve the separation efficiency significantly, and thus lays the foundation for promoting the industrial application of the hollow fiber 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 2 indicating a maximum peak in a range of diffraction angle 2 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.

The present invention provides a titanosilicate separation membrane which can also be used for separating a mixed gas containing a molecule having a relatively small size, has high durability in a high temperature environment, and has a high permeation rate and a high selectivity for a mixed gas containing water vapor. A titanosilicate separation membrane has a CHA-type titanosilicate crystal structure formed on a porous support, wherein aluminum is not substantially contained in the backbone of the titanosilicate crystal structure, and the titanosilicate crystal structure is constituted by silicon, oxygen, and titanium.

The present invention relates to a process for producing a porous support-zeolite membrane composite, which comprises forming a CHA type zeolite membrane on a porous support by a hydrothermal synthesis in the presence of seed crystals, wherein an FAU type zeolite is used as the seed crystals.

The present invention aims at providing a method for producing a high-concentration alcohol from a water-alcohol mixture, in which the overall process is efficient and the present invention relates to a production method of a high-concentration alcohol, including a water adsorption step of adsorbing water of a water-alcohol mixture on an adsorption column to obtain a first concentrated alcohol, a water desorption step of introducing an alcohol to obtain a hydrous alcohol, and a membrane separation step of introducing the hydrous alcohol into a membrane separation unit provided with a membrane composite containing zeolite having an SiO.sub.2/Al.sub.2O.sub.3 molar ratio of 5 to 15 to obtain a second concentrated alcohol.

The invention relates to a method for preparing a hierarchical porous zeolite membrane and an application thereof, comprising the following steps: a mesoporous structure-directing agent is added to limit the growth of zeolite crystals, and self-assembled in the crystallization process to generate a mesoporous structure. Based on a seed crystal induced secondary nucleation mechanism, this method can realize one-step hydrothermal synthesis of hierarchical porous zeolite membrane with the advantages of mild and controllable synthesis conditions, simple process, good repeatability, reduced energy consumption and cost savings. The hierarchical porous zeolite membrane prepared by the method has good cut-off performance, and the cut-off molecular weight is adjustable between 200 to 500,000 Da.

A method of manufacturing a separation membrane structure comprising a step of forming a first to n.sup.th zeolite membranes on a surface of a porous substrate by n repetitions (wherein n is an integer greater than or equal to 2) of formation of a zeolite membrane by a method of hydrothermal synthesis. The following formula (1) is established in relation to the step of forming the first to the n.sup.th zeolite membranes. (Formula 1) N.sub.1/N.sub.0+0.1T.sub.2n/T.sub.12N.sub.1/N.sub.0+2 (Wherein, N.sub.1 denotes a permeation rate of a predetermined gas in the substrate after formation of the first zeolite membrane, N.sub.0 denotes a permeation rate of a predetermined gas in the substrate before formation of the first zeolite membrane, T.sub.1 is a time required for formation of the first zeolite membrane, and T.sub.2n is a total time required for formation of the second to the n.sup.th zeolite membranes.)

A method for preparing a thin or thick film, including the aligning non-spherical seed crystals on a flat portion of at least one surface of the substrate such that an a-axis, a b-axis, and/or a c-axis are oriented according to a certain rule; and exposing the aligned seed crystals to a solution for enabling the growth of the seed crystals to thereby form and grow a film from the seed crystals using a secondary growing technique.