Zeolite Membrane Uniformity via Seed Crystal Orientation
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Solution Overview
Problem
Existing methods for producing zeolite membranes face challenges in achieving uniform thickness and orientation of crystal c-axis vertical to the support surface, leading to defects and reduced separation efficiency, especially when using supports with large surface areas or complex shapes.
Innovation Solution
A process involving a seeding sol with a specific molar ratio of water to silica and controlled hydrothermal synthesis conditions to form zeolite seed crystals on the support surface, followed by membrane growth, ensuring uniform adhesion and orientation of the c-axis of zeolite crystals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hydrothermal synthesis is performed in the presence of a support without seed crystals, then the support surface is exposed and membrane thickness becomes too large, but uniform adhesion and thin membrane formation are difficult to achieve
Solution Approach 1:
The patent applies preliminary action by forming zeolite seed crystals on the support surface before the main hydrothermal synthesis. The seed crystals are prepared in advance using a seeding sol with specific composition (water/silica molar ratio of 10-50) and treated at 90-130°C for 3-18 hours. This preliminary seed formation ensures uniform nucleation sites are established on the support surface, which then guides the subsequent membrane growth to achieve uniform thickness and proper orientation without requiring complex adhesion procedures.
2Reliability
If seed crystals are adhered onto support non-uniformly, then membrane thickness becomes non-uniform, but this causes defects and cracks in the membrane during activation treatment
Solution Approach 1:
The patent applies parameter changes by optimizing the chemical composition parameters of the seeding sol, specifically setting the water/silica molar ratio between 10-50. This parameter optimization ensures that seed crystals form uniformly on the support surface. Additionally, the temperature parameter is controlled at 90-130°C for 3-18 hours, which facilitates uniform nucleation and adhesion. These controlled parameter changes prevent non-uniform seed distribution that would lead to membrane defects during activation.
3Ease of manufacture
If dip coating or rubbing methods are used to adhere seed crystals, then adhesion can be achieved, but uniform adhesion is difficult especially on large surface area supports
Solution Approach 1:
The patent applies self-service by using a seeding sol that automatically forms uniform seed crystals on the support surface without requiring external mechanical assistance. The sol composition (water/silica molar ratio of 10-50) and treatment conditions (90-130°C for 3-18 hours) are designed so that the seed crystals self-nucleate and self-adhere uniformly across the support surface. This eliminates the need for dip coating or rubbing methods that struggle with large surface areas, as the chemical process inherently distributes seeds uniformly regardless of support size.
4Manufacturing precision
If zeolite seed crystal adheres non-uniformly, then membrane thickness is non-uniform, but this reduces separation ability and reproducibility
Solution Approach 1:
The patent applies parameter changes by optimizing the water/silica molar ratio in the seeding sol to the range of 10-50, which is critical for uniform seed crystal formation. This parameter optimization ensures that seed crystals nucleate uniformly across the support surface, leading to uniform membrane thickness during hydrothermal synthesis. The temperature parameter of 90-130°C for 3-18 hours further ensures consistent seed adhesion. By controlling these parameters, the patent achieves both high manufacturing precision in membrane uniformity and improved production efficiency through reduced defects and better reproducibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a dense, uniform zeolite membrane with high separation ability and reduced defects, suitable for applications like gas separation and pervaporation, with improved reproducibility and efficiency.
Implementation Method 1
heating the heat-resistant vessel to form a zeolite seed crystal on the surface of the support
Implementation Method 2
allowing the zeolite seed crystal to grow to form a zeolite membrane on the surface of the support
Data Source
AI summary
A process for producing a zeolite membrane comprising a seed crystal forming step of placing, in a pressure-resistant vessel, a seeding sol containing silica, water and a structure-directing agent and a support in a state that the support is immersed in the seeding sol and heating the heat-resistant vessel to form a zeolite seed crystal on the surface of the support, and a membrane formation step of allowing the zeolite seed crystal to grow to form a zeolite membrane on the surface of the support. In the seed crystal forming step, the molar ratio of water/silica in the seeding sol is set 10 to 50 and the heating of the pressure-resistant vessel is conducted at 90 to 130° C. The crystal c-axis of the present zeolite membrane is oriented in a direction vertical to the surface of the support and its thickness is uniform.