Molecular Insights into the CO₂ Mineralization Process with Tricalcium Silicate

Area of Science:

• Geochemistry
• Materials Science
• Chemical Engineering

Background:

• Carbon dioxide (CO2) mineralization is key for capture, utilization, and storage, transforming industrial waste into valuable materials.
• Understanding the reaction mechanisms and kinetics of CO2 mineralization, particularly with tricalcium silicate (C3S), is crucial for process optimization.
• Current knowledge lacks detailed insights into rate-limiting steps and optimal conditions for industrial applications.

Purpose of the Study:

• To investigate the reaction kinetics and conversion rates of C3S during CO2 mineralization under various conditions.
• To elucidate the influence of temperature, pressure, and solid waste dispersion on the mineralization process.
• To model the effect of a water film on C3S reactivity in simulated moist environments.

Main Methods:

• Utilized reactive molecular dynamics simulations to examine C3S-CO2 interactions and reaction pathways.
• Developed a computational model of C3S within a water film to mimic realistic environmental conditions.
• Analyzed the impact of varying temperature (e.g., 328 K), pressure (up to 1.0 MPa), and particle dispersion on reaction rates.

Main Results:

• The CO2 mineralization reaction involving C3S proceeds rapidly at 328 K.
• Elevated pressures above 1.0 MPa negatively impact conversion rates, while temperature shows minimal effect.
• Increased fragmentation of solid waste enhances reaction rates by improving dispersion and surface area.
• The presence of a water film significantly hinders mass transfer, thereby slowing down the overall reaction speed.

Conclusions:

• Optimizing CO2 mineralization requires careful control of temperature and pressure, favoring lower pressures and specific temperatures like 328 K.
• Enhancing solid waste fragmentation is a viable strategy to accelerate CO2 capture efficiency.
• The insulating effect of water films must be considered and potentially mitigated in industrial CO2 mineralization designs.
• This study provides critical mechanistic insights for advancing CO2 mineralization technologies.