Bimodal Separation Membrane for Methane Nitrogen Purification
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Solution Overview
Problem
Existing methods for separating methane and nitrogen are inefficient due to the similar molecular diameters of the two gases, leading to insufficient separation performance.
Innovation Solution
A separation membrane structure comprising a porous support with a first separation membrane having an average pore diameter of 0.32 to 0.44 nm and a second separation membrane with added metal cations or complexes that preferentially adsorb nitrogen, enabling selective permeation of nitrogen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single separation membrane is used, then the structure is simple, but the separation performance is insufficient due to similar molecular diameters of methane and nitrogen
Solution Approach 1:
The single separation membrane is divided into two distinct membranes with different functions: a first separation membrane with specific pore diameter (0.32-0.44 nm) for size-based separation, and a second separation membrane with metal cations or complexes for selective adsorption. This segmentation allows each membrane to address specific separation challenges, achieving high separation performance despite the similar molecular diameters of methane and nitrogen.
Solution Approach 2:
The invention uses composite membrane structures where the second separation membrane incorporates metal cations (such as Li+, Na+, K+, Ca2+, Sr2+, Ba2+) or metal complexes within its matrix. This composite approach combines the size-sieving capability of the first membrane with the selective adsorption properties of metal-containing materials in the second membrane, creating a synergistic effect that overcomes the limitation of single-membrane systems.
2Manufacturing precision
If metal cations or complexes are added to enhance nitrogen adsorption, then nitrogen selectivity improves, but the manufacturing complexity increases
Solution Approach 1:
The metal cations or complexes are incorporated into the second separation membrane during its formation process or through subsequent treatment steps. By preparing the membrane structure in advance with the appropriate metal components, the selective adsorption capability is built-in from the start, avoiding the need for complex post-manufacturing modifications or multiple processing steps.
Solution Approach 2:
The invention optimizes specific parameters such as the type and concentration of metal cations (Li+, Na+, K+, Ca2+, Sr2+, Ba2+), the pore diameter of the first membrane (0.32-0.44 nm), and the composition of the second membrane to achieve high nitrogen selectivity. By carefully controlling these parameters during manufacturing, the process becomes more predictable and easier to scale up despite the added complexity of using metal-containing materials.
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 membrane structure effectively separates methane and nitrogen by increasing nitrogen partial pressure through adsorption and selective permeation, enhancing both separation and permeation properties.
Implementation Method 1
a first separation membrane which has an average pore diameter of greater than or equal to 0.32 nm and less than or equal to 0.44 nm
Implementation Method 2
The second separation membrane includes addition of at least one of a metal cation or a metal complex that tends to adsorb nitrogen in comparison to methane
Data Source
AI summary
A separation membrane structure comprises a porous support, a first separation membrane formed on the porous support, and a second separation membrane formed on the first separation membrane. The first separation membrane has an average pore diameter of greater than or equal to 0.32 nm and less than or equal to 0.44 nm. The second separation membrane includes addition of at least one of a metal cation or a metal complex that tends to adsorb nitrogen in comparison to methane.