Direct flue gas CO2 mineralization using activated serpentine: Exploring the reaction kinetics by experiments and population balance modelling

Abstract

Abstract Avoiding CO 2 emissions to the atmosphere by its safe and permanent storage is required for all options within the CCS framework. Only mineral carbonation allows for a sequestration process, where the carbon is rapidly converted to its chemically most stable form, a carbonate. So far, most researchers looking into mineral carbonation focused on routes that involve an aqueous medium, where carbonation takes place under an atmosphere of pure CO 2 , either in a single or multi-step process. We have started to investigate a novel approach to aqueous mineral carbonation where the costly capture step is avoided by the direct mineralization of flue gas CO 2 at the point source. For the present study, we have built a set-up to perform mineralization experiments under a variety of conditions in both batch or flow-through mode. The residence times of the reactor solution and gas phase involved can be freely adjusted: The design allows for flowing both the feed solution and the flue gas continuously through an autoclave that contains a sample of activated serpentine. The use of online ion chromatography and in-situ Raman spectroscopy allows monitoring magnesium concentration as well as the solids and dissolved phases throughout an experimental run. A population balance equation model has been developed and its solution was coupled with the continuous flow-through reactor model. The experimental data serves as input to the model in order to regress reaction rates under a variety of operating conditions. A precise knowledge of the dissolution and precipitation kinetics is required for the optimal design and scale-up of the mineralization process. Moreover, the ultimate particle size distribution is of key importance for mineralization product processing and product applications.