Borate-Containing Membranes for Oxidative Stability in Gas Separation
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Solution Overview
Problem
Existing selectively permeable polymeric membranes used for gas separation, such as hydrogen purification and carbon dioxide sequestration, are prone to oxidation when exposed to air at elevated temperatures, making them unsuitable for many industrial applications.
Innovation Solution
Development of membranes comprising a support layer and a selective polymer layer with an oxidatively stable carrier, such as quaternaryammonium hydroxide or quaternaryammonium fluoride, dispersed within a hydrophilic polymer matrix, which includes a borate additive, enabling selective permeability and oxidative stability at temperatures above 100°C, allowing the use of air as a sweep gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing selectively permeable polymeric membranes are used for gas separation, then gas separation functionality is achieved, but oxidative stability deteriorates when exposed to air at elevated temperatures
Solution Approach 1:
The patent employs composite materials by combining quaternary ammonium hydroxide or fluoride carriers with borate additives dispersed in a hydrophilic polymer matrix. This composite structure provides both the gas separation functionality of the carrier and the oxidative stability of the borate-polymer system, resolving the contradiction between membrane performance and oxidation resistance at elevated temperatures
Solution Approach 2:
The patent changes the chemical parameters of the membrane system by introducing borate additives in specific concentrations (0.1-10 wt%) to modify the oxidation resistance properties. This parameter change transforms the membrane from oxidation-prone to oxidation-stable, enabling reliable operation in air at temperatures above 100°C while maintaining gas separation capabilities
2Productivity
If temperature is increased above 100°C for industrial gas separation, then separation efficiency improves, but membrane oxidation accelerates
Solution Approach 1:
The patent utilizes parameter changes by adjusting the temperature operating range above 100°C while simultaneously modifying the membrane composition to include borate additives. This dual parameter adjustment allows the system to achieve high separation efficiency at elevated temperatures without sacrificing membrane stability, as the borate-containing composite resists oxidation even at these higher operating temperatures
3Productivity
If air is used as sweep gas for enhanced mass transfer, then separation productivity increases, but oxidative degradation of membrane worsens
Solution Approach 1:
The patent applies the blessing in disguise principle by converting the harmful oxidative environment (air as sweep gas) into a beneficial operating condition. The borate-containing membrane composition is specifically designed to resist oxidation, allowing air to be used as sweep gas at elevated temperatures to enhance mass transfer and productivity without causing membrane degradation. The previously harmful oxidation becomes a tolerated or even advantageous feature for process intensification
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 exhibit enhanced selective permeability for gases like carbon dioxide and hydrogen sulfide, maintaining stability and selectivity even at elevated temperatures, making them suitable for industrial gas separation processes.
Implementation Method 1
The membranes can exhibit selective permeability to gases. For example, the membranes can be used to selectively remove carbon dioxide and/or hydrogen sulfide from hydrogen and/or nitrogen.
Implementation Method 2
the membranes can exhibit oxidative stability at temperatures above 100° C. As such, the membranes can be compatible with the use of air as a sweep gas at temperatures above 100° C.
Data Source
AI summary
Membranes, methods of making the membranes, and methods of using the membranes are described herein. The membranes can comprise a support layer, and a selective polymer layer disposed on the support layer. The selective polymer layer can comprise an oxidatively stable carrier and a borate additive dispersed within a hydrophilic polymer matrix. The oxidatively stable carrier can comprise a quaternaryammonium hydroxide carrier (e.g., a mobile carrier such as a small molecule quaternaryammonium hydroxide, or a fixed carrier such as a quaternaryammonium hydroxide-containing polymer), a quaternaryammonium fluoride carrier (e.g., a mobile carrier such as a small molecule quaternaryammonium fluoride, or a fixed carrier such as a quaternaryammonium fluoride-containing polymer), or a combination thereof. The borate additive can comprise a borate salt, a boric acid, or a combination thereof. The membranes can exhibit selective permeability to gases. As such, the membranes can be for the selective removal of carbon dioxide and/or hydrogen sulfide from hydrogen and/or nitrogen.