Zeolite Membrane Pore Geometry for Methane Nitrogen Separation
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Solution Overview
Problem
Existing methods for separating methane and nitrogen, such as adsorption and membrane separation, do not achieve sufficient separation performance, particularly under high pressure conditions due to the similar molecular diameters of methane and nitrogen.
Innovation Solution
A separation membrane structure comprising a porous support body with a zeolite membrane having pores with a major diameter to minor diameter ratio greater than 1.0, where the minor diameter is between 0.30 nm and 0.35 nm, allowing selective permeation of nitrogen over methane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional adsorption methods using molecular sieve or ETS-4 are used, then nitrogen can be removed from mixed gas, but separation performance is insufficient under high pressure conditions due to similar molecular diameters of methane and nitrogen
Solution Approach 1:
The invention uses a zeolite membrane with specifically controlled pore dimensions (minor diameter 0.30-0.35 nm, major diameter 0.40-0.55 nm, and an aspect ratio greater than 1.0) to achieve size-based molecular sieving. The elongated pore shape creates a more selective filtration pathway that distinguishes between methane and nitrogen molecules more effectively than conventional adsorption materials, resolving the insufficient separation performance under high pressure conditions.
Solution Approach 2:
The invention changes the critical parameters of the separation medium by precisely controlling the pore geometry (minor diameter, major diameter, and aspect ratio) of the zeolite membrane. This parameter optimization creates a pore structure that exploits the subtle differences in molecular dimensions and interaction properties between methane and nitrogen, enabling effective separation where conventional methods fail, particularly under high pressure.
2Reliability
If membrane separation using CHA-type or DDR-type zeolite membranes is used, then nitrogen separation is achieved, but separation performance remains insufficient under high pressure conditions
Solution Approach 1:
The invention applies local quality by creating a zeolite membrane with non-uniform pore characteristics - specifically elongated pores with distinct minor and major diameters and an aspect ratio greater than 1.0. This localized geometric feature within the membrane structure creates preferential pathways that selectively accommodate nitrogen molecules while excluding methane, providing enhanced separation performance under high pressure conditions compared to conventional zeolite membranes with isotropic pore structures.
Solution Approach 2:
The invention employs asymmetry by designing pores with different dimensional characteristics in different directions (minor diameter versus major diameter, with aspect ratio > 1.0). This asymmetric pore geometry creates directional selectivity that exploits the differences in molecular shape and size between nitrogen and methane, enabling effective separation under high pressure where symmetric pore structures fail.
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 configuration enables efficient separation of methane and nitrogen, reducing nitrogen concentration in mixed gases even under high pressure, by inhibiting methane entry into the pores while allowing nitrogen to permeate, thus enhancing separation performance.
Implementation Method 1
a zeolite membrane formed on the porous support body and comprising pores having a major diameter and a minor diameter. The ratio of the major diameter to the minor diameter is greater than 1.0. The minor diameter is greater than or equal to 0.30 nm and less than or equal to 0.35 nm
Implementation Method 2
allowing selective permeation of nitrogen over methane
Data Source
AI summary
A separation membrane structure comprises a porous support body, a zeolite membrane formed on the porous support body and comprising pores having a major diameter and a minor diameter. The ratio of a major diameter to a minor diameter is greater than 1.0. The minor diameter is greater than or equal to 0.30 nm and less than or equal to 0.35 nm.