Degradation study of piperazine, its blends and structural analogs for CO2 capture: A review

Postcombustion carbon dioxide (CO2) capture using amine scrubbing is an emerging technology to mitigate CO2 emissions. Benchmark amines used in this technology are monoethanolamine (MEA), methyldiethanolamine (MDEA), and diethanolamine (DEA). Amines undergo irreversible reactions, resulting degradation of the solvent under process operating conditions. Degradation of solvent may create environmental concerns, increased costs as well as corrosion in the process equipment. Piperazine (PZ) has been investigated as a novel amine solvent for CO2 capture. It has high CO2 capture capacity and absorption rate with thermal and oxidative degradation resistance. This study discusses the thermal and oxidative degradation of PZ under process operating conditions. A critical review of various parameters, such as the effect of temperature, amine concentration, CO2 loading (α), partial pressure of oxygen (O2) and presence of metal ions on rate of degradation has been reported. Chemistry of degradation products and mechanisms of degradation of PZ are reported for better understanding of PZ degradation kinetics. In addition, degradation of PZ blends, structural analogs, and diamines is focused, and behavior of their degradation is highlighted. Furthermore, kinetics of formation and degradation of nitrosamines through PZ is also discussed.