Lithium-Exchanged Zeolite Adsorbent for Low-Pressure CO2 Removal
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Solution Overview
Problem
Current carbon dioxide removal systems in aerospace applications, such as the International Space Station, require improvements in adsorbent capacity, size, weight, power consumption, and waste heat emissions, with a need for a high-performance adsorbent that selectively removes CO2 at low partial pressures while minimizing regeneration capacity.
Innovation Solution
A process using a lithium-exchanged X-zeolite adsorbent bed that operates at low carbon dioxide partial pressures, selectively adsorbing CO2 from air and regenerating the bed through temperature or pressure swing desorption, maintaining nitrogen levels in the air and reducing system size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a modified 5A sodium zeolite is used for CO2 removal, then the system can achieve CO2 removal function, but the adsorbent capacity at low partial pressures is insufficient
Solution Approach 1:
The patent changes the cationic composition parameters of the zeolite adsorbent, specifically using a combination of lithium, sodium, and calcium ions in optimized ratios. This chemical parameter modification enables the adsorbent to achieve high CO2 capacity at low partial pressures while maintaining reliable removal performance in space applications
2Productivity
If the adsorbent bed size is increased to improve CO2 removal capacity, then the CO2 removal rate increases, but the system mass and weight increase
Solution Approach 1:
The patent modifies the chemical composition parameters of the zeolite to optimize CO2 adsorption capacity per unit mass. By adjusting the cationic ratio (Li:Na:Ca) and performing specific heat treatments, the adsorbent achieves higher efficiency, allowing smaller bed sizes for the same CO2 removal rate, thus reducing system mass for space missions
Solution Approach 2:
The patent utilizes the porous structure of faujasite-type zeolite with optimized pore dimensions and surface properties. The porous material's high surface area and tunable pore structure enable enhanced CO2 adsorption capacity per unit volume and mass, improving productivity while controlling system weight
3Productivity
If the adsorbent bed size is increased to improve CO2 removal capacity, then the CO2 removal rate increases, but the power consumption increases
Solution Approach 1:
The patent optimizes the thermal and chemical parameters of the zeolite adsorbent to enhance CO2 uptake at lower temperatures and pressures. This parameter optimization improves adsorption efficiency per unit of energy input, allowing high productivity with reduced power consumption for regeneration and operation in space systems
4Productivity
If the adsorbent bed size is increased to improve CO2 removal capacity, then the CO2 removal rate increases, but the waste heat emission increases
Solution Approach 1:
The patent modifies the thermal parameters and heat capacity characteristics of the zeolite through compositional adjustments and heat treatment processes. These changes improve the adsorbent's thermal management properties, enabling high CO2 removal rates with reduced waste heat generation, which is critical for maintaining thermal balance in space missions
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 lithium-exchanged X-zeolite adsorbent increases CO2 capacity and selectivity, reducing system size and weight, while maintaining air composition and minimizing power consumption and waste heat, enabling efficient CO2 removal and regeneration in aerospace applications.
Implementation Method 1
The lithium-exchanged faujasite adsorbent selectively separates carbon dioxide from air using either pressure swing (Skylab) or combined pressure swing/thermal swing (ISS) methodologies
Implementation Method 2
regenerating the adsorbent bed when it becomes saturated
Data Source
AI summary
A process for removal of carbon dioxide from air using lithium-exchanged X-zeolites at low carbon dioxide partial pressures is provided. The process is particularly useful in applications where fresh air is not available and exhaled air needs to be recycled. An apparatus for carrying out the process is also provided.