Lithium hydroxide as a high capacity adsorbent for CO₂ capture: experimental, modeling and DFT simulation

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Carbon dioxide (CO2) emissions drive climate change, necessitating efficient capture technologies.
• Developing cost-effective and high-capacity adsorbents is crucial for CO2 mitigation strategies.

Purpose of the Study:

• To investigate the CO2 adsorption potential of monohydrate Lithium hydroxide (LiOH).
• To determine optimal operating conditions for CO2 capture using LiOH.
• To elucidate the adsorption mechanism and thermodynamic properties of LiOH for CO2.

Main Methods:

• Experimental investigation in a fixed-bed reactor.
• Response Surface Methodology (RSM) with central composite design for parameter optimization.
• Isotherm, kinetic, and thermodynamic modeling.
• Density Functional Theory (DFT) for theoretical analysis.

Main Results:

• Optimal conditions for CO2 capture: 333 K, 4.72 bar, 200 micron particle size, yielding 559.39 mg/g adsorption capacity.
• Hill model provided an excellent fit for adsorption isotherms.
• Adsorption kinetics followed a second-order model, indicating chemisorption.
• Thermodynamic analysis revealed spontaneous and exothermic CO2 adsorption.

Conclusions:

• Monohydrate Lithium hydroxide (LiOH) is a highly effective adsorbent for CO2 capture.
• Optimal conditions were identified for maximizing LiOH's adsorption capacity.
• The adsorption process is governed by chemisorption and is thermodynamically favorable.