Microporous Coordination Polymers for CO2 Separation
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Solution Overview
Problem
Current materials for CO2 adsorption, such as zeolites and microporous coordination polymers, have limitations in CO2 uptake at low relative pressures and ambient temperatures, and existing methods for separating close-boiling gas mixtures like ethane/ethylene or propane/propylene are energy-intensive.
Innovation Solution
Development of microporous coordination polymers containing Co, Ni, Mg, and/or Zn with specific organic linkers, referred to as Co-74, Ni-74, and Mg-74, which exhibit high affinity for CO2 and olefins, enabling efficient separation of CO2, ethylene, ethane, propylene, and propane at low pressures and ambient temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional adsorbent materials like zeolites or traditional microporous coordination polymers are used, then CO2 uptake capacity is achieved, but CO2 affinity at low relative pressures and ambient temperature remains insufficient
Solution Approach 1:
The patent introduces open metal sites (OMS) at specific locations within the microporous coordination polymer framework. These OMS are created by using metals like Cu, Ni, or Zn with specific coordination geometries that leave unsaturated coordination sites exposed in the pores. This local modification of the framework structure creates highly active centers for CO2 adsorption without altering the overall framework topology, thereby enhancing CO2 affinity at low pressures while maintaining structural stability
Solution Approach 2:
The patent combines organic linkers (such as trimesic acid or terephthalic acid) with metal ions (Cu, Ni, Zn) to form hybrid microporous coordination polymers. This composite structure integrates the advantages of both organic components (porosity, stability) and metal components (open metal sites, high affinity for CO2), achieving superior CO2 uptake at low pressures compared to either component alone
2Productivity
If chemical adsorption by amine beds is used for CO2 sequestration, then CO2 removal efficiency is improved, but energy consumption for amine recycling increases significantly
Solution Approach 1:
The patent replaces chemical adsorption (chemisorption) mechanisms with physical adsorption (physisorption) mechanisms enhanced by open metal sites. Instead of using amine chemicals that require high-energy regeneration through heating and stripping, the invention uses metal-coordination polymer materials where CO2 binds through physisorption at open metal sites. This substitution eliminates the need for chemical recycling processes, reducing energy consumption while maintaining high CO2 removal efficiency through reversible adsorption-desorption cycles
Solution Approach 2:
The patent changes the adsorption mechanism from chemical bonding (chemisorption) to enhanced physical adsorption (physisorption) through the introduction of open metal sites. This parameter change in the adsorption mechanism allows for reversible binding that can be easily controlled by pressure and temperature changes, enabling low-energy regeneration cycles without requiring the high temperatures and complex chemistry of amine-based systems
3Quantity of substance
If zeolite synthesis methods are used, then CO2 uptake performance is achieved, but synthesis requires high temperature conditions and lacks synthetic flexibility
Solution Approach 1:
The patent changes the synthesis parameters from high-temperature solid-state reactions (zeolite synthesis) to lower-temperature solution-phase coordination chemistry. The microporous coordination polymers are synthesized by mixing metal salts and organic linkers in solvent at moderate temperatures (often room temperature or mild heating), followed by solvent removal. This parameter change in synthesis conditions dramatically improves ease of manufacture while allowing systematic variation of metal and linker components to tune CO2 uptake performance
Solution Approach 2:
The patent employs a universal synthesis approach using modular organic linkers (carboxylic acids, heterocyclic compounds) and metal ions that can be combined in various configurations to create different microporous coordination polymer structures. This universal chemistry platform allows systematic exploration of structure-property relationships and easy optimization of CO2 uptake performance by simply changing the metal or linker component, providing both ease of manufacture and high CO2 uptake performance
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
These materials demonstrate exceptional CO2 uptake and selectivity for olefins over paraffins, achieving high separation efficiency with reduced energy requirements, outperforming previous materials in CO2 adsorption and gas separation processes.
Implementation Method 1
Physical adsorption of carbon dioxide is an emergent technology. Such a material provides high adsorption at low relative pressures and ambient temperature.
Implementation Method 2
These materials show good selectivities for olefin compounds over paraffin compounds. These materials demonstrate exceptional CO2 uptake and selectivity for olefins over paraffins
Data Source
AI summary
A method of separating a target component from a chemical mixture comprising contacting a chemical mixture with a microporous coordination polymer. The microporous polymer is described by the formula:[M2(C8H2O6)]where M is a transition metal, rare earth metal, or other element from the groups consisting of IIA through VB.