Method of preparing hierarchical porous channel molecular sieve membrane and application thereof

Patent metadata

Field	Value
Publication number	US-11554348-B2
Application number	US-201716348819-A
Country	US
Kind code	B2
Filing date	Jun 9, 2017
Priority date	Nov 10, 2016
Publication date	Jan 17, 2023
Grant date	Jan 17, 2023

Abstract

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.

First claim

What is claimed is:

1. A method for preparing a hierarchical porous zeolite membrane, wherein a mesoporous structure-directing agent is introduced and self-assembly is carried out on a membrane layer to form a mesoporous structure;
the method comprising the following steps:
(1) preparation of seed crystal: zeolite particles are prepared into a seed crystal suspension;
(2) seed crystal coating: a continuous and compact seed crystal layer is coated on a porous support by a dip-coating method, dried and calcined to obtain a support coated with the seed crystal;
(3) synthesis of hierarchical porous zeolite membrane: a silicon source, an aluminum source, an alkali source, the mesoporous structure-directing agent and deionized water are mixed and prepared into a mother liquor of secondary growth; two ends of the support coated with the seed crystal are sealed and placed in a reactor filled with the mother liquor, and then dynamical crystallization is carried out under tumbling condition, finally, the mesoporous structure-directing agent is removed to obtain the hierarchical porous zeolite membrane;
wherein
the mesoporous structure-directing agent is selected from a surfactant and an organic silane coupling agent in step (3);
the surfactant is one of cetyl trimethyl ammonium bromide (CTAB), hexadecyl trimethyl ammonium chloride (CTAC) and triblock copolymer (EO 20 PO 70 EO 20 , P123); and
the organic silane coupling agent is one of dimethyl octadecyl [3-trimethoxysilylpropyl] ammonium chloride (TPOAC), dimethyl hexadecyl [3-trimethoxysilylpropyl] ammonium chloride (TPHAC), and dimethyl dodecyl [3-trimethoxysilylpropyl] ammonium chloride (TPDAC).

2. The method according to claim 1 , wherein in step (3) the silicon source, the aluminum source, the alkali source, the mesoporous structure-directing agent and the deionized water are mixed according to a molar ratio of 1:0.005-2:0.4-4:0.01-0.05:60-250.

3. The method according to claim 1 , wherein
the silicon source in step (3) is one of tetraethyl orthosilicate, fumed silica, sodium silicate and silica sol;
the aluminum source is one of aluminum sulfate, sodium metaaluminate, aluminum isopropoxide and aluminum hydroxide; and
the alkali source is one of sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, quaternary ammonium alkali compound, fatty amine compound or alcohol amine compound.

4. The method according to claim 1 , wherein step (3) comprises the following steps: the silicon source, the aluminum source, the alkali source, the mesoporous structure-directing agent and the deionized water are mixed according to a molar ratio of 1:0.005-2:0.4-4:0.01-0.05:60-250; then, they are stirred and aged for 1 to 10 h to prepare into the mother liquor of secondary growth; the two ends of the support coated with the seed crystal are sealed with a raw material tape, fixed and placed in the reactor filled with the mother liquor, then the dynamical crystallization is carried out under tumbling condition at a rate of 2 to 20 rad/min and hydrothermal synthesis at 100 to 180° C. for 4 to 24 h;
after complete reaction, the membrane is taken out and washed with further deionized water to become neutral, dried and calcinated in a muffle furnace at 400 to 600° C. for 3 to 8 h, so as to remove the mesoporous structure-directing agent and obtain the hierarchical porous zeolite membrane.

5. The method according to claim 1 , wherein the porous support is hollow fiber, sheet- or tube-type, and has single-channel or multi-channel shape.

6. The method according to claim 1 , wherein the porous support is a hollow fiber porous support, wherein the average pore diameter of the hollow fiber porous support is 0.1 to 5 μm, the outer diameter of the hollow fiber is 0.5 to 5 mm, and the porosity is 10 to 60%, and the hollow fiber porous support has single-channel or multi-channel shape.

7. The method according to claim 1 , wherein the zeolite configuration in step (1) is one of MFI, LTA, FAU, MOR, CHA, BEA, LTL, SOD, GIS, OFF, MTN or AEL.

8. The method according to claim 1 , wherein the zeolite particles prepared in step (1) have a particle diameter of 50 nm to 500 nm.

9. A zeolite membrane prepared by the method according to any one of claims 1 to 8 .

Assignees

• Nanjing University Of Technology

Inventors

• Gu Xuehong
• Yao Xun
• Peng Li

Classifications

• C01B39/54

  Phosphates, e.g. APO or SAPO compounds · CPC title

• C01B39/40 Primary

  using at least one organic template directing agent · CPC title

• C01P2002/72

  by d-values or two theta-values, e.g. as X-ray diagram · CPC title

• C01P2004/03

  obtained by SEM · CPC title

• B01D69/081

  characterised by the fibre diameter · CPC title