Precipitating Characteristics of Potassium Bicarbonate Using Concentrated Potassium Carbonate Solvent for Carbon Dioxide Capture. Part 1. Nucleation

Abstract

Potassium carbonate is considered a promising solvent for carbon dioxide (CO2) capture as it is cost-effective and environmentally benign when compared to traditional amine-based solvents. In order to increase absorption capacity, the use of concentrated potassium carbonate solvent has been proposed in which CO2 absorption results in precipitation of bicarbonate. Understanding the formation of the solids in that system is important if this is to be used for CO2 capture. In this work, the precipitation behavior in the ternary system of potassium carbonate–potassium bicarbonate–water was studied in a batch cooling crystallizer equipped with Focused Beam Reflectance Measurement (FBRM) and an Optimax workstation. The solubility data were validated using a regressed Electrolyte Non-Random Two Liquid (ENRTL) activity model developed in Aspen Plus. The precipitate was determined as kalicinite with hexagonal prism shape by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The nucleation kinetics were evaluated using the metastable zone width method and induction time method. Results indicated that in the studied ternary system there were two separate regions corresponding to different nucleation mechanisms, which were defined by the cooling rate. The supersaturation of potassium bicarbonate and the concentration of potassium carbonate determined the nucleation kinetics. On the basis of the calculated nucleation kinetics, the continuous growth mechanism of the crystals was further examined using the surface entropy value and SEM images.

Recent Progress in Continuous Crystallization of Pharmaceutical Products: Precise Preparation and Control

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Process modifications for a hot potassium carbonate‐based CO2capture system: a comparative study

“…Secondly, MEA suffers oxidative and thermal degradations under the high temperature associated with typical post‐combustion capture conditions. This requires frequent replenishment of the solvent with a fresh solution, thereby increasing the quantity of solvent usage and cost . Finally, the high carbon footprint associated with the mass production of this solvent makes it unattractive for large‐scale applications in post‐combustion capture processes .…”

“…This requires frequent replenishment of the solvent with a fresh solution, thereby increasing the quantity of solvent usage and cost. [17][18][19][20][21] Finally, the high carbon footprint associated with the mass production of this solvent makes it unattractive for large-scale applications in post-combustion capture processes. 22 For these reasons, a significant amount of research is being directed towards two main areas: developing lower cost and more environmentally friendly solvents, and designing various process modifications to minimise the energy penalties.…”

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