(542a) Development of a Novel Hot-Carbonate Process for Post-Combustion CO2 Capture: Role of Organic Promoters in Enhanced Absorption and Bicarbonate Crystallization

Development of cost-effective new technologies are essential for separating and capturing CO₂ from power plant flue gases and retrofitting the CO₂ capture and sequestration (CCS) technology with minimum cost penalty. Currently available monoethanol amine (MEA)-based processes are highly energy-intensive and expensive. A novel hot-carbonate absorption process with bicarbonate crystallization-enabled high pressure stripping (Hot-CAP) is being developed to reduce the energy requirement for CO₂stripping and compression.

In the Hot-CAP, CO₂ is absorbed into a concentrated potassium carbonate solution (about 40wt%) at elevated temperatures (60-80^oC). A carbonate–based system tends to have a slower CO₂ absorption rate compared with the MEA. A key technical issue is thus to enhance the absorption rate to a level that is comparable to MEA-based processes. In this study, five organic catalysts and three potassium amino acid salts were investigated as organic promoter to accelerate the absorption rate of CO₂ into the carbonate solution. The rate of CO₂ absorption was measured using a stirred tank reactor (STR) reactor. Results indicated that some selected organic catalysts enhanced the absorption rate significantly and the absorption rates were comparable with that of 5M MEA. The absorption rate depended on the promoter dose and CO₂ loading level in the solution. Additionally, the crystallization of the CO₂ rich solution without and with organic promoters was further investigated under various process conditions. Results from crystallization revealed that potassium bicarbonate prevailed in crystal solids formed.

This presentation will provide a summary of results from the studies of absorption and crystallization in the presence of promoters.