A Diamine-Based Integrated Absorption–Mineralization Process for Carbon Capture and Sequestration: Energy Savings, Fast Kinetics, and High Stability

The high energy requirement of amine regeneration and the uncertainty of safe disposal of the captured CO₂ remain big challenges to the large-scale implementation of amine scrubbing process for CO₂ capture. Mineral carbonation represents a safe and permanent route to capture and store CO₂ with net energy production but typically proceeds at a slow reaction rate. Here, we present a new integrated absorption and mineralization (IAM) process that couples a diamine-based CO₂ absorption with fly-ash-triggered amine regeneration. The technical feasibility of the IAM process using 3-diethylaminopropylamine (DEAPA) and CaO-containing materials such as CaO and coal fly ashes was verified, and the reaction mechanism involved was investigated. It was found that CaO and CaO-rich coal fly ash were effective to regenerate DEAPA via the decomposition of DEAPA carbamate species and the formation of calcium carbonate precipitates. Furthermore, the diamine-based IAM process displayed a fast kinetics and a high stability for CO₂ sequestration and can reduce the leachability of some heavy metals in the fly ash. These process properties render this diamine-based IAM process a great potential for carbon capture and sequestration applications.