A DDR-type zeolite seed crystal has an average particle diameter of less than or equal to 0.2 μm, and an average aspect ratio of less than or equal to 1.3.

A composite molecular sieve membrane, preparation method and use thereof are provided in the embodiments. The composite molecular sieve membrane includes a support layer and a molecular sieve membrane layer, wherein the support layer is a high-porosity and porous ceramic which is made of nano- or submicron ceramic powder materials or ceramic material precursors prepared through an electrospinning process. The high-porosity and porous ceramic, is adjustable from 40% to 83%. The composite molecular sieve membrane of the embodiments uses the porous ceramic prepared through an electrospinning process as the support layer, and the support layer has a flat and continuous surface, high porosity, uniform and adjustable pore sizes, low-tortuosity pore channels, and high mechanical strength; the flux of the composite molecular sieve membrane is increased, besides, the seed crystals can attach effectively due to the fibrous pore channels of the support layer, ensuring the adhesion amount of seed crystals.

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.

Disclosed are a CHA zeolite membrane and a method of preparing the same, and more particularly, a CHA zeolite membrane having high capacity to separate CO.sub.2/N.sub.2 and CO.sub.2/CH.sub.4 even under wet conditions using a membrane produced using a synthetic precursor having a controlled ratio of Si and Al, a method of preparing the same, and a method of capturing and removing carbon dioxide using the membrane.

A method for manufacturing a zeolite membrane structure comprises an immersion step for immersing a porous substrate in a synthetic sol, and a synthesis step for hydrothermally synthesizing a zeolite membrane on a surface of the porous substrate that has been immersed in the synthesis so. When the foamability of the synthetic sol is measured by a Ross-Miles method under a condition of 25 degrees C., the foam height after elapse of 5 minutes from completion of down flow is less than or equal to 5 mm.

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 for producing a crystalline film comprising zeolite and/or zeolite-like crystals on a porous substrate is described. The method has the steps of: providing a porous support; modifying at least a surface of the top-layer of said porous support by treatment with a composition having one or more cationic polymer(s); rendering at least the outer surface of said porous support hydrophobic by treatment with a composition having one or more hydrophobic agent(s); subjecting said treated porous support to a composition having zeolite and/or zeolite-like crystals thereby depositing and attaching zeolite and/or zeolite-like crystals on said treated porous support, and growing a crystalline film of zeolite and/or zeolite-like crystals on said treated porous support and calcination. Crystalline films find use in a variety of fields such as in the production of membranes, catalysts etc.

A zeolite membrane complex includes a porous support, and a zeolite membrane formed on the support and composed of an 8-membered ring zeolite. The zeolite membrane is selectively permeable to hydrogen sulfide rather than nitrogen for a gas containing nitrogen and hydrogen sulfide.

A zeolite membrane complex comprises: a support; and a zeolite membrane formed on the support. The membrane is of SAT-type zeolite, and in an X-ray diffraction pattern obtained by X-ray irradiation to the zeolite membrane, a peak intensity around 2θ=13.9° is 1.5 times or more a peak intensity around 2θ=8.5°.

Ammonia is made in a system that includes a conversion reactor for performing a Haber-Bosch process. Effluent streams from the conversion reactor, which include an ammonia component and excess hydrogen and nitrogen reactants, are fed to a membrane separator that includes NaA zeolite membranes disposed on one or more hollow porous supports. The NaA zeolite membranes are highly selective for the ammonia component, allowing the ammonia to be collected from a lumen of the membranes as a product and enriching the excess hydrogen and nitrogen reactants for reuse in the conversion reactor. These systems and the methods of their use are effective to replace and/or modify the energy-intensive condensation/recycling steps in the traditional Haber-Bosch process used to condense NH3 from the exiting stream of the reactor. The selective removal of ammonia by high quality NaA membranes helps to shift the ammonia evolution reaction.