Abstract
The reaction of wollastonite with CO2 accompanied by SO2 and NO2 in the presence of a chloride-rich brine (230 g/L NaCl, 15 g/L CaCl2, 5 g/L MgCl2) at temperatures relevant to injection conditions (333 K) in carbon capture and storage (CCS) were investigated within the joint BMWi (Federal Ministry for Economic Affairs and Energy) research project CLUSTER. The reaction which describes the formation of wollastonite during metamorphism is reversed and shows a strong temperature dependence. Wollastonite reacts in the presence of CO2 ( C ¯ ) in aqueous conditions to form calcium carbonate and amorphous silicon oxide. At 333 K and 2 MPa the carbonation reaction of wollastonite ( C ¯ C S ) is fast (<24 h). To determine the conversion rate of the reaction quantitatively different methods were used and compared: Powder X-ray diffraction (PXRD) with the Rietveld method and differential scanning calorimetry with thermogravimetry, coupled with a mass spectrometer (DSC-TG/MS) for quantitative phase analysis and for determination of the carbonation. The carbonation (CO2 accompanied by SO2 and NO2) of natural wollastonite at 333 K in presence of chloride-rich brine was rather fast (almost complete after 24 h reaction time).
Highlights
The Intergovernmental Panel on Climate Change (IPCC) climate report, 2018 [1] concluded that reduction of CO2 emissions was necessary, because the current CO2 concentrations are still considerably rising and currently amount to 408 ppm [2]
The present study considers the back reaction by carbonation of wollastonite forming CaCO3 and SiO2 as a base [10] within the joint BMWi (German Federal Ministry for Economic Affairs and Energy) research ([6,7,8,11,12] CLUSTER)
Carbonation of wollastonite in a chloride-rich brine (230 g/L NaCl, 15 g/L CaCl2, 5 g/L MgCl2 ) as aqueous solution with CO2 accompanied by 70 ppm SO2 and 70 ppm NO2 at 333
Summary
The Intergovernmental Panel on Climate Change (IPCC) climate report, 2018 [1] concluded that reduction of CO2 emissions was necessary, because the current CO2 concentrations are still considerably rising and currently amount to 408 ppm [2]. It is a mandatory challenge to reduce CO2 emissions. One possible option being currently investigated and discussed [3] is carbon capture and storage (CCS). Using CCS, CO2 emissions from different sources (energy production, steel, and cement industries) could be reduced by finding and exploring suitable deep geologic formations (e.g., sandstones) for CO2 storage. The formations considered for injection could be on- or offshore which could be in part already exploited former gas fields [3]. The casing and sealing of boreholes at storage sites must feature high reliability, because CO2 has an impact on the stability of conventional hydrated cements [4,5], i.e., it leads to degradation due to carbonation
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