Metal Halide Salt Hydrolysis for Low-Energy CO2 Capture
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Solution Overview
Problem
Current CO2 capture technologies, such as solvent-based systems, sorbent-based systems, and membrane-based systems, face challenges in scalability, energy efficiency, and environmental impact, particularly in large-scale air contactor design and ocean CO2 removal, with high regeneration energy requirements and environmental risks.
Innovation Solution
A method involving the hydrolysis of metal halide salts to form hydrohalic acid and hydroxide salts, which are then used to react with metal carbonate salts to release CO2, with the recycling of metal halide salts to reduce energy consumption and environmental disruption, specifically using CaCl2 hydrolysis to regenerate hydroxide-based CO2-capture sorbents at lower temperatures and integrate with direct air capture systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydroxide-based solvents like KOH are used for CO2 capture, then capture efficiency and scalability are improved, but regeneration energy requirements increase significantly
Solution Approach 1:
The patent introduces metal halide salts (e.g., CaCl2, MgCl2) as intermediary substances that facilitate the regeneration process. These salts react with the hydroxide-based sorbent to form metal carbonate salts, which then decompose to release CO2 at lower temperatures, thereby mediating the energy-intensive regeneration process and reducing overall energy requirements
Solution Approach 2:
The patent changes the chemical parameters of the regeneration process by using metal halide salts to convert the regeneration mechanism from direct thermal decomposition to a chemical reaction pathway. This parameter change enables regeneration at lower temperatures and reduced energy input while maintaining high CO2 capture efficiency
2Productivity
If calcination-based regeneration is used for hydroxide-based solvents, then CO2 is effectively released, but high temperature and high energy consumption occur
Solution Approach 1:
Metal halide salts serve as intermediaries that enable CO2 release at lower temperatures. The halide salt reacts with the hydroxide sorbent to form a metal carbonate intermediate, which decomposes more readily than the original hydroxide, thereby mediating the temperature reduction while maintaining effective CO2 release
Solution Approach 2:
The patent replaces the purely thermal decomposition mechanism (calcination) with a chemical reaction mechanism involving metal halide salts. This substitution of the regeneration mechanism allows CO2 release at lower temperatures without sacrificing efficiency, as the chemical reaction pathway is more favorable than direct thermal decomposition
3Productivity
If NaCl electrochemical splitting is used to produce HCl and NaOH for ocean CO2 removal, then CO2 can be converted, but energy consumption becomes unacceptably high
Solution Approach 1:
The patent replaces electrochemical splitting with a thermal hydrolysis process for generating HCl and NaOH from NaCl. This substitution of the energy input method (electrical vs. thermal) and the reaction mechanism significantly reduces energy consumption while maintaining the ability to convert CO2 in ocean water
Solution Approach 2:
The patent changes the fundamental parameters of the salt-splitting process by using thermal hydrolysis instead of electrochemical splitting. This parameter change in the reaction type and energy input method reduces electricity consumption from unacceptably high levels to much lower, more viable levels for ocean CO2 removal
4Object-affected harmful factors
If lime addition is used for ocean CO2 removal, then ocean health can be improved, but significant lime production and environmental disruption are required
Solution Approach 1:
The patent enables the ocean itself to provide the necessary chemicals for CO2 removal. By using thermal hydrolysis of NaCl in seawater to generate HCl and NaOH, the system utilizes the ocean's own salt content rather than requiring external lime production, thereby making the ocean self-sufficient and eliminating the harmful environmental disruption from lime mining and processing
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
This approach lowers the energy required for CO2 regeneration and ocean CO2 removal, making direct air capture more viable and reducing environmental risks by decreasing energy costs and emissions, while also being more tolerant of seawater impurities and avoiding acidification.
Implementation Method 1
hydrolyzing a metal halide salt to form a hydrohalic acid and a hydroxide salt of the metal in the metal halide salt
Implementation Method 2
reacting the hydrohalic acid with the metal carbonate salt, wherein the metal carbonate salt is a carbonate salt of the alkaline earth metal or alkali metal, to form CO2 and the metal halide salt
Data Source
AI summary
A method of treating a metal carbonate salt includes hydrolyzing a metal halide salt to form a hydrohalic acid and a hydroxide salt of the metal in the metal halide salt. The metal includes an alkaline earth metal or an alkali metal. The method includes reacting the hydrohalic acid with the metal carbonate salt, wherein the metal carbonate salt is a carbonate salt of the alkaline earth metal or alkali metal, to form CO2 and the metal halide salt. At least some of the metal halide salt formed from the reacting of the hydrohalic acid with the metal carbonate salt is recycled as at least some of the metal halide salt in the hydrolyzing of the metal halide salt to form the hydrohalic acid and the hydroxide salt.