Aromatic Co-Polyimide Membranes for Sour Gas Separation
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Solution Overview
Problem
Current membrane technologies for natural gas separations face challenges such as high energy requirements, high capital costs, and inadequate performance in handling high H2S concentrations and heavy hydrocarbons, leading to inefficiencies in sour gas separation and helium recovery.
Innovation Solution
Development of aromatic block co-polyimide membranes derived from 6FDA-DAM-type homo-polyimide, which exhibit superior efficiency, productivity, and resistance to penetrant-induced plasticization, enabling effective separation of CO2, H2S, and helium from natural gas even at high H2S concentrations and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional absorption or adsorption processes are used for acid gas removal, then separation capability is achieved, but energy requirements and capital costs increase significantly
Solution Approach 1:
The patent replaces mechanical separation systems (absorption towers, adsorption beds) with a membrane-based separation system that utilizes selective permeability. The membrane module substitutes complex mechanical processes with a passive diffusion-based separation mechanism, eliminating the need for thermal regeneration and reducing energy consumption while maintaining separation capability.
Solution Approach 2:
The patent employs porous or dense membrane materials with specific pore structures that enable selective gas permeation. The membrane's porous structure or dense matrix allows acid gases (CO2, H2S) to pass through while retaining natural gas components, achieving separation without the energy-intensive processes of conventional methods.
2Device complexity
If conventional membrane materials are used, then device complexity is reduced, but performance in handling high H2S concentrations and heavy hydrocarbons deteriorates
Solution Approach 1:
The patent uses composite membrane materials combining polyimide polymers with specific additives or cross-linked structures that provide both mechanical integrity and chemical resistance. The composite structure enables the membrane to withstand high H2S concentrations and heavy hydrocarbon environments while maintaining separation performance, overcoming the limitations of conventional single-material membranes.
Solution Approach 2:
The patent modifies membrane material parameters such as glass transition temperature, free volume, and chemical composition to enhance resistance to plasticization by heavy hydrocarbons and degradation by H2S. By adjusting these material parameters, the membrane maintains its separation capability and structural stability in aggressive sour gas conditions.
3Use of energy by moving object
If membrane separation is implemented, then energy consumption is reduced, but selectivity and permeability performance must be improved
Solution Approach 1:
The patent optimizes the membrane's local properties by creating regions with different compositions or structures within the membrane layer. This includes developing asymmetric membranes with a selective skin layer and a support layer, or incorporating localized functional groups that enhance selectivity for acid gases while maintaining adequate permeability, thus achieving high performance without increasing energy consumption.
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 aromatic co-polyimide membranes demonstrate enhanced permeability and selectivity for CO2 and H2S, maintaining performance at moderate pressures and high H2S levels, outperforming conventional membranes and reducing energy consumption and capital costs.
Implementation Method 1
glassy polyimide is one type of polymeric membrane that has been investigated for acid gas separations from natural gas. These high glass transition temperature (Tg) (Tg>about 300° C.) materials develop certain acid gas separation capability based on size selectivity
Implementation Method 2
These high glass transition temperature (Tg) (Tg>about 300° C.) materials develop certain acid gas separation capability based on size selectivity
Implementation Method 3
Certain existing membranes require stringent pretreatment for water and heavy hydrocarbons content, as the membranes are very susceptible to swelling and plasticization in the presence of heavy hydrocarbons; benzene, toluene, and xylene (BTX); water; and other condensable gases
Data Source
AI summary
Co-polyimide membranes for separating components of sour natural gas including at least three distinct moieties polymerized together, the moieties including a 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) based moiety; a 2,4,6-trimethyl-m-phenylenediamine (DAM) based moiety; and at least one component selected from the group consisting of: a 4,4′-(hexafluoroisopropylidene)dianiline (6FpDA) based moiety; a 9,9-bis(4-aminophenyl) fluorene (CARDO) based moiety; a 2,3,5,6-tetramethyl-1,4-phenylenediamine (durene diamine) based moiety; a 2,2′-bis(trifluoromethyl)benzidine (ABL-21) based moiety; a 3,3′-dihydroxybenzidine based moiety; and a 3,3′-(hexafluoroisopropylidene)dianiline based moiety.