Halogen-Substituted CARDO Polyimide Membranes for Sour Gas Separation
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Solution Overview
Problem
Current gas processing technologies, such as amine absorption, are energy-intensive and costly for removing CO2 and H2S from natural gas, and existing polymeric membranes lack the efficiency and resistance to plasticization needed for effective sour gas separation.
Innovation Solution
Development of polyimide gas separation membranes based on halogen-substituted 9,9-bis(4-aminophenyl)fluorene (CARDO) monomers, which are reacted with dianhydride monomers to form polymers that enhance solubility and diffusivity, improving CO2 and H2S separation while resisting plasticization at high pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amine absorption technology is used to remove CO2 and H2S from natural gas, then the removal efficiency of acid gases is improved, but energy consumption and operating costs increase significantly
Solution Approach 1:
The patent replaces the mechanical/chemical absorption process (amine absorption towers with pumping and heating systems) with a membrane-based separation system that utilizes pressure-driven gas permeation. This substitution eliminates the need for energy-intensive heating and regeneration processes while achieving comparable or superior acid gas removal efficiency through the selective permeability of the polyimide membrane.
Solution Approach 2:
The patent changes the operating parameters from temperature-driven absorption (requiring heating to regenerate amine solutions) to pressure-driven membrane separation. By operating at elevated pressures (30-100 atm) on the feed side, the system achieves high flux and selectivity for CO2 and H2S removal without thermal energy input, fundamentally altering the energy profile of the separation process.
2Ease of manufacture
If conventional polymeric membranes are used for gas separation, then capital cost is reduced, but resistance to plasticization under high pressure is insufficient
Solution Approach 1:
The patent employs a composite polymer structure incorporating halogen-substituted CARDO monomers with rigid dianhydride units. This composite molecular architecture combines the flexibility needed for gas permeation with rigid aromatic and halogenated segments that resist chain rearrangement and plasticization under high pressure, maintaining membrane integrity and selectivity at pressures up to 100 atm.
Solution Approach 2:
The patent modifies the polymer chain parameters by introducing halogen substituents (Cl, Br, I) and rigid aromatic structures into the polymer backbone. These structural parameter changes increase the glass transition temperature and reduce chain mobility, thereby enhancing resistance to plasticization while maintaining adequate gas permeability through controlled free volume.
3Temperature
If existing polyimide membranes are used, then thermal stability is maintained, but CO2 and H2S permeability and selectivity are insufficient for effective sour gas separation
Solution Approach 1:
The patent introduces local structural variations by incorporating halogen-substituted CARDO monomers at specific positions within the polymer chain. These localized halogenated aromatic segments create regions of enhanced polarity and specific interactions with acid gas molecules, increasing CO2 and H2S permeability and selectivity while the overall polyimide structure maintains thermal stability through its aromatic backbone.
Solution Approach 2:
The patent changes the chemical composition parameters of the polyimide by incorporating halogen-substituted diamine monomers with specific functional groups. These compositional changes adjust the polymer's polarity, free volume, and interaction parameters with target gases, optimizing CO2 and H2S permeability and selectivity coefficients while preserving the thermal stability characteristic of polyimide structures.
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 membranes demonstrate improved CO2 and H2S permeability and selectivity, reducing capital and operating expenditures, and maintaining performance under harsh conditions, thus offering a more efficient and cost-effective solution for natural gas purification.
Implementation Method 1
gas separation membrane including a polyimide polymer
Implementation Method 2
enhance solubility and diffusivity, improving CO2 and H2S separation
Implementation Method 3
resisting plasticization at high pressures
Data Source
AI summary
Embodiments described in examples herein provide a gas separation membrane including a polyimide polymer including a monomer having a structure including:wherein when X1=X2, X1 and X2 are selected from F, Cl, Br, or I and wherein when X1 and X2 are different elements, X1 and X2 are independently selected from H, F, Cl, Br, or I.