The Carbonation of Wollastonite: A Model Reaction to Test Natural and Biomimetic Catalysts for Enhanced CO2 Sequestration
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AuthorLorenzo, Fulvio Di; Ruiz-Agudo, Cristina; Ibañez-Velasco, Aurelia; Gil-San Millán, Rodrigo; Navarro, Jorge A. R.; Ruiz-Agudo, Encarnacion; Rodriguez-Navarro, Carlos
CarbonationWollastoniteCatalystsCarbonic anhydraseMOFsCarbon capture and storage
Lorenzo, F.Di. [et al.]. The Carbonation of Wollastonite: A Model Reaction to Test Natural and Biomimetic Catalysts for Enhanced CO2 Sequestration. Minerals 2018, 8, 209; doi:10.3390/min8050209.
SponsorshipThis research was funded by the Spanish Government (grants CGL2015-70642-R, CGL2015-73103-EXP, CTQ2017-84692-R), EU FEDER funding, the University of Granada (“Unidad Científica de Excelencia” UCE-PP2016-05) and the Junta de Andalucía (grant P11-RNM-7550 and Research Group RNM-179). We thank the personnel of the Centro de Instrumentación Científica (CIC) of the University of Granada for their help during TG-DSC, FESEM, -XRD, and ICP-OES analyses.
One of the most promising strategies for the safe and permanent disposal of anthropogenic CO2 is its conversion into carbonate minerals via the carbonation of calcium and magnesium silicates. However, the mechanism of such a reaction is not well constrained, and its slow kinetics is a handicap for the implementation of silicate mineral carbonation as an effective method for CO2 capture and storage (CCS). Here, we studied the different steps of wollastonite (CaSiO3) carbonation (silicate dissolution -> carbonate precipitation) as a model CCS system for the screening of natural and biomimetic catalysts for this reaction. Tested catalysts included carbonic anhydrase (CA), a natural enzyme that catalyzes the reversible hydration of CO2(aq), and biomimetic metal-organic frameworks (MOFs). Our results show that dissolution is the rate-limiting step for wollastonite carbonation. The overall reaction progresses anisotropically along different [hkl] directions via a pseudomorphic interface-coupled dissolution–precipitation mechanism, leading to partial passivation via secondary surface precipitation of amorphous silica and calcite, which in both cases is anisotropic (i.e., (hkl)-specific). CA accelerates the final carbonate precipitation step but hinders the overall carbonation of wollastonite. Remarkably, one of the tested Zr-based MOFs accelerates the dissolution of the silicate. The use of MOFs for enhanced silicate dissolution alone or in combination with other natural or biomimetic catalysts for accelerated carbonation could represent a potentially effective strategy for enhanced mineral CCS.