Nitrogen-Doped Carbon Sorbent for Humid CO2 Adsorption
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Solution Overview
Problem
Existing carbon capture technologies for CO2 separation are energy-intensive, costly, and lack selectivity for CO2 capture from gas streams containing water vapor, particularly in applications like post-combustion gases.
Innovation Solution
A carbon sorbent formulation comprising nitrogen-rich pyridine and pyrrole structures on its surface, with a bulk density greater than 0.40 g/cm3, formed by mixing carbohydrates, corn starch, and a nitrogen-containing material, followed by carbonization and activation, to enhance CO2 adsorption capacity and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional CO2 separation methods (chemical absorption, physical absorption, membrane separation, cryogenic methods) are used, then CO2 can be separated from gas streams, but the process becomes energy-intensive and costly
Solution Approach 1:
The patent replaces energy-intensive chemical absorption processes with physical adsorption using solid carbon-based adsorbent materials. This substitution eliminates the need for thermal regeneration cycles and high-energy steam stripping, achieving CO2 separation through physisorption at lower temperatures and pressures.
Solution Approach 2:
The invention employs porous carbon-based adsorbent materials with tailored pore structures and surface chemistries to selectively capture CO2. The porous structure provides high surface area for adsorption while maintaining selectivity through controlled pore sizes and surface functional groups.
2Quantity of substance
If conventional adsorbents (zeolites, carbon molecular sieves, activated carbons) are used for CO2 capture, then physical adsorption occurs, but selectivity for CO2 relative to water vapor is insufficient in streams containing significant water vapor
Solution Approach 1:
The patent modifies the local surface chemistry of carbon-based adsorbents by introducing specific functional groups (oxygen-containing groups such as carboxyl, carbonyl, and hydroxyl groups) at the adsorbent surface. This local modification creates preferential binding sites for CO2 molecules while maintaining hydrophobic character that repels water vapor, achieving high selectivity in humid gas streams.
Solution Approach 2:
The invention creates composite carbon-based adsorbent materials combining bulk carbon structures with surface-functionalized layers. These composite materials integrate the high surface area and porosity of activated carbons with the selective binding properties of functionalized surfaces, achieving both high CO2 capacity and high selectivity in the presence of water vapor.
3Quantity of substance
If chemical absorption using aqueous alkanolamine solutions is used, then CO2 forms a complex that can be separated, but large capital expenses are required for construction and operation
Solution Approach 1:
The patent employs solid carbon-based adsorbent materials that can be regenerated and reused multiple cycles without degradation. This replaces expensive chemical absorption systems with simpler, more durable solid adsorbents that require minimal infrastructure and have lower capital expenses while maintaining high CO2 capture capacity.
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 carbon sorbent exhibits improved CO2 capacity and selectivity over conventional materials, capturing CO2 more efficiently while minimizing water vapor adsorption, suitable for use in pressure swing adsorption systems.
Implementation Method 1
a carbon sorbent for removal of carbon dioxide from a gaseous material comprises a surface including nitrogen atoms, greater than about 25.0 atomic percent of the nitrogen atoms at the surface of the carbon sorbent forming part of pyridine groups
Implementation Method 2
Other methods of CO2 capture include pressure swing adsorption (PSA) and vacuum swing adsorption (VSA). Such methods use physical adsorbents, such as zeolites, carbon molecular sieves, or activated carbons, for capturing the CO2.
Data Source
AI summary
A carbon sorbent for removing carbon dioxide from a gaseous material includes a surface composition including carbon, nitrogen, and oxygen. The nitrogen atoms at the surface of the carbon sorbent may be present in pyridone, pyrrole, and pyridine. The surface of the carbon sorbent may include lactone groups and pyrone groups. The carbon sorbent may have a bulk density greater than about 0.40 grams per cubic centimeter and may exhibit a carbon dioxide capacity of at least 11.0 weight percent at 30° C. and 760 mmHg. The carbon sorbent may be formed using amino acids to provide the nitrogen for the carbon sorbent. In addition, the use of processing aids during the formation of the carbon sorbent facilitates the formation of a denser carbon sorbent. Related methods of forming the carbon sorbent and pellets of the carbon sorbent are also disclosed.