Dual-Phase Membranes for Low-Temperature CO2 Separation
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Solution Overview
Problem
Conventional carbon capture and separation technologies, such as polymer membranes and solvent-based solutions, are economically and energetically costly, limiting their widespread application for reducing greenhouse gas emissions, and existing dual-phase membranes are restricted to high temperatures, making them inefficient for low-temperature CO2 separation from flue gases.
Innovation Solution
Dual-phase membranes with a solid porous support and a molten salt phase containing alkali metal hydroxides and oxide ion transfer agents, such as borates, nitrates, phosphates, vanadates, and niobates, which facilitate CO2 separation by utilizing water vapor concentration gradients for active transport, enabling operation at lower temperatures (125-300°C) and improving permeation rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polymer membranes and solvent-based solutions are used for CO2 separation, then CO2 capture can be achieved, but economic and energy costs are too high for widespread application
Solution Approach 1:
The patent changes the operational temperature parameter from conventional high temperatures to low temperatures (125-300°C) by incorporating oxide ion transfer agents into the molten salt phase. This parameter change enables CO2 separation at economically viable temperatures, reducing energy consumption while maintaining high separation efficiency
Solution Approach 2:
The patent creates a composite molten salt phase by combining alkali metal hydroxides with oxide ion transfer agents (borates, nitrates, phosphates, vanadates, niobates, or sulfates). This composite material achieves both high CO2 permeation rates and low operational temperatures, resolving the contradiction between separation efficiency and energy cost
2Temperature
If dual-phase membranes operate at high temperatures (≥550°C), then CO2 separation can be achieved, but the technology is inefficient for low-temperature applications
Solution Approach 1:
The patent fundamentally changes the temperature parameter by using oxide ion transfer agents that enable the molten salt phase to operate at low temperatures (125-300°C) while maintaining high CO2 separation efficiency, inverting the conventional high-temperature requirement
Solution Approach 2:
The oxide ion transfer agents act as intermediaries that facilitate CO2 transport at low temperatures by mediating the chemical reactions between CO2 and the molten salt phase, enabling efficient separation without requiring high temperatures
3Temperature
If molten hydroxides are used to increase CO2 permeation rates, then operational temperatures can be decreased to ≥400°C, but further temperature reduction to 125-300°C is not achievable
Solution Approach 1:
Oxide ion transfer agents serve as intermediaries that enable CO2 permeation at temperatures below 400°C by facilitating the chemical transport mechanism at lower temperatures, thus breaking the temperature barrier while maintaining high permeation rates
Solution Approach 2:
The composite molten salt phase combining alkali metal hydroxides with oxide ion transfer agents creates a new material system that achieves both low operational temperatures (125-300°C) and high CO2 permeation rates, resolving the contradiction between temperature reduction and permeation rate maintenance
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 described dual-phase membrane technology achieves high-performance CO2 separation across a wide range of temperatures, reducing operational costs and energy consumption, and enhances selectivity over inert gases, making it more efficient than conventional methods.
Implementation Method 1
These oxide ion transfer agents can also chemically couple the permeation of carbon dioxide from the feed gas with the water vapor of a steam sweep to enable an active transport membrane mechanism
Implementation Method 2
This active transport mechanism can thus power carbon dioxide separation with the larger concentration gradients (partial pressure) of water vapor instead of solely relying on the concentration gradients of carbon dioxide to power gas separation by the membrane
Implementation Method 3
These oxide ion transfer agents can thereby function in the liquid phase to affect gas sorption reactions as an oxide ion transfer catalyst or to control the acid/base equilibrium of oxide ions
Implementation Method 4
Dual phase membranes are an alternative technology that can conventionally capture CO2 at temperatures ≥550° C. with a molten carbonate phase
Data Source
AI summary
Dual phase membranes include a porous support providing a solid phase having a matrix of connected pores, and a liquefiable ion transport phase within the pores of the porous support. The ion transport phase is formed of at least one alkali metal hydroxide, and at least one oxide ion transport agent providing a source of ions selected from the group consisting of borate ions, nitrate ions, phosphate ions, vanadate ions, niobate ions or sulfate ions. The at least one alkali metal hydroxide may be selected from the group consisting of NaOH, KOH, LiOH, RbOH, CsOH and mixtures thereof. The oxide ion transport agent is preferably present in the ion transport phase in an amount between about 1 to about 30 molar %. Substantially lower operational temperatures may be realized when the membrane is used to separate CO2 from a feed gas.