Zeolite Membrane Defect Reduction via Oxygen-Rich Calcination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing zeolite membranes on complex-shaped substrates, such as monoliths, result in uneven membrane thickness and defects due to the removal of structure-directing agents, leading to poor separation performance and high defect amounts.
Innovation Solution
Increasing the oxygen concentration during the structure-directing agent removal step to facilitate the decomposition of these agents, thereby reducing defects and achieving uniform membrane performance across large membrane areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the structure-directing agent removal step is performed in ambient atmosphere, then the process is simple and easy to operate, but defects are generated in thick membrane areas leading to poor separation performance
Solution Approach 1:
The patent changes the atmospheric parameters (oxygen concentration, temperature profile) during the structure-directing agent removal step. Specifically, it uses an oxygen-rich atmosphere (30-50 vol% O2) and implements a controlled temperature increase (5-10°C/min) to ensure complete decomposition of structure-directing agents even in thick membrane regions, thereby eliminating defects while maintaining process feasibility
Solution Approach 2:
The patent performs preliminary heating at a moderate temperature (e.g., 200-400°C) for a extended period (2-12 hours) in an oxygen-rich atmosphere before final high-temperature treatment. This preliminary action ensures that structure-directing agents in thick membrane areas are partially decomposed or activated, preventing defect formation during subsequent rapid heating or service conditions
2Reliability
If hydrothermal synthesis is performed to form zeolite membrane on porous substrate, then a zeolite membrane is formed with molecular sieve function, but uneven thickness and defects occur on large complex-shaped substrates
Solution Approach 1:
The patent optimizes hydrothermal synthesis parameters including temperature (80-200°C), time (1-48 hours), and the ratio of structure-directing agent to silica (0.001-0.1 mol/mol). These parameter adjustments control the crystallization rate and membrane growth kinetics, enabling uniform membrane formation on large complex-shaped substrates while maintaining molecular sieve functionality
Solution Approach 2:
The patent applies a slurry containing zeolite seed particles to the porous substrate surface before hydrothermal synthesis. This preliminary seeding action provides nucleation sites that guide uniform membrane growth across the entire substrate surface, including complex geometries, ensuring consistent thickness and eliminating defects that would otherwise occur during crystallization
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
The process ensures a zeolite membrane with reduced defects and enhanced separation performance, even on large, complex-shaped substrates, by decomposing the structure-directing agents in an atmosphere with an oxygen concentration of 35 vol% or more, resulting in a more uniform and effective gas separation membrane.
Implementation Method 1
removing the structure-directing agent in the atmosphere having an O2 concentration of 35 vol% or more
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
There are provided a process for producing a zeolite membrane which, even when large, has few defects and which has higher separation performance than conventional zeolite membranes, and a zeolite membrane obtained by the process. In the process, the structure-directing agent is removed in the atmosphere having an O2 concentration of 22.0 vol% or more. Specifically, the process includes: a particle adhesion step of allowing zeolite particles functioning as seeds to flow down the surface of the substrate by means of the weight of the slurry itself, thereby adhering to the substrate and a membrane-forming step of forming a zeolite membrane on the substrate by immersing the substrate having the zeolite particles adhering thereto in sol containing the structure-directing agent for hydrothermal synthesis, thereby forming a zeolite membrane on the substrate.