Potassium Silicate as Low-Temperature Binder in 3D-Printed Porous Structures for CO₂ Separation

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Developing efficient and regenerable sorbents is crucial for effective carbon dioxide (CO2) capture.
• Traditional sorbents often face limitations in mechanical stability and regeneration efficiency.
• 3D-printing offers a novel approach to engineer structured sorbent materials with tailored properties.

Purpose of the Study:

• To develop novel 3D-printed activated carbon sorbents using potassium silicate as a low-temperature binder.
• To evaluate the CO2 capture performance and regeneration characteristics of these structured sorbents.
• To investigate the potential for homogeneous heating and improved working capacity.

Main Methods:

• Direct 3D printing of activated carbon with potassium silicate binder.
• Characterization using N2, Ar, CO2 sorption, and Hg-intrusion porosimetry.
• Thermogravimetric analysis-looping experiments for CO2 capture and regeneration studies.
• In situ X-ray diffraction for mechanism confirmation and electrical resistivity measurements for heating.

Main Results:

• A mechanically stable, 3D-printed activated carbon sorbent was successfully fabricated.
• The sorbent demonstrated a 25% increase in CO2 capture capacity with room-temperature regeneration.
• Optimizing regeneration temperature to 150 °C nearly tripled the working capacity to 0.76 mmol/g.
• In situ XRD confirmed a mixed physisorption and chemisorption mechanism involving potassium bicarbonates.
• The monolith exhibited homogeneous electrical resistivity for uniform Joule heating.

Conclusions:

• Potassium silicate enables the low-temperature 3D printing of robust, regenerable CO2 sorbents.
• The developed structured sorbents offer significantly improved CO2 capture capacity and working efficiency.
• Homogeneous Joule heating presents a viable method for efficient regeneration of the 3D-printed sorbent.