CO2 capture systems based on saccharides and organic superbases

Area of Science:

• Green Chemistry
• Materials Science
• Chemical Engineering

Background:

• Developing efficient and sustainable carbon dioxide (CO2) capture technologies is critical for mitigating climate change.
• Abundant and renewable resources like saccharides offer a promising alternative to traditional CO2 sorbents.
• Organic superbases present unique reactivity profiles for CO2 interactions.

Purpose of the Study:

• To investigate novel CO2 capture systems utilizing abundant saccharides (D-mannose, D-glucose, β-cyclodextrin, alginic acid, mannitol) combined with organic superbases (tetramethylguanidine (TMG), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)).
• To evaluate the CO2 uptake capacity and reaction mechanisms of these saccharide-superbase systems.
• To assess the stability and reversibility of CO2-loaded systems using Differential Scanning Calorimetry (DSC).

Main Methods:

• Preparation and testing of various saccharide-superbase combinations at different molar ratios.
• Quantification of CO2 uptake by weight percentage (wt%).
• Analysis of reaction products (carbonate vs. carbamate) and degree of alcohol group conversion.
• Thermal analysis (DSC) to study system stability and reversibility.

Main Results:

• TMG-based systems showed high CO2 uptake, but TMG also reacted directly with CO2, leading to product competition.
• DBU-based systems were employed to favor carbonate formation, circumventing TMG's direct reaction.
• A D-mannose:DBU ratio of 0.625 achieved 13.9% CO2 uptake with 3.3/5 alcohol groups converted.
• An improved stirring system enabled a D-glucose:DBU ratio of 1:1, resulting in 11.5% CO2 uptake with 2.47/5 alcohol groups converted.

Conclusions:

• Saccharide-DBU systems, particularly D-mannose and D-glucose, demonstrate effective CO2 capture capabilities.
• Optimizing the saccharide:superbase ratio and employing advanced mixing are crucial for maximizing CO2 uptake.
• The studied systems show potential for reversible CO2 capture, warranting further investigation into their stability and regeneration.