ZeroCAL: Eliminating Carbon Dioxide Emissions from Limestone's Decomposition to Decarbonize Cement Production

Adriano Leão; Marie Collin; Swarali Ghodkhande; Arnaud Bouissonnié; Xin Chen; Benjamin Malin; Yiming Liu; Geanna Hovey; Jagannathan Govindhakannan; Erika La Plante; David Jassby; Torben Gädt; Lorenzo Corsini; Dante Simonetti; Fabian Rosner; Gaurav Sant

doi:10.1021/acssuschemeng.4c03193

ZeroCAL: Eliminating Carbon Dioxide Emissions from Limestone's Decomposition to Decarbonize Cement Production

ACS Sustain Chem Eng. 2024 Oct 10;12(43):15762-15787. doi: 10.1021/acssuschemeng.4c03193. eCollection 2024 Oct 28.

Authors

Adriano Leão^{1

2}, Marie Collin^{1

2}, Swarali Ghodkhande^{1

2}, Arnaud Bouissonnié^{1

2}, Xin Chen^{1

2

3}, Benjamin Malin^{1

2}, Yiming Liu², Geanna Hovey^{1

2}, Jagannathan Govindhakannan^{1

2}, Erika La Plante^{2

4}, David Jassby^{2

5

6}, Torben Gädt⁷, Lorenzo Corsini³, Dante Simonetti^{2

8}, Fabian Rosner^{2

5}, Gaurav Sant^{1

1

5

6

9}

Affiliations

¹ Laboratory for the Chemistry of Construction Materials (LC2), Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095, United States.
² Institute for Carbon Management (ICM), University of California, Los Angeles, California 90095, United States.
³ Equatic Inc., Los Angeles, California 90402, United States.
⁴ Department of Materials Science and Engineering, University of California, Davis, California 95616, United States.
⁵ Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095, United States.
⁶ California Nanosystems Institute (CNSI), University of California, Los Angeles, California 90095, United States.
⁷ Department of Chemistry, Technical University of Munich, Garching 85747, Germany.
⁸ Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095, United States.
⁹ Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, United States.

Abstract

Limestone (calcite, CaCO₃) is an abundant and cost-effective source of calcium oxide (CaO) for cement and lime production. However, the thermochemical decomposition of limestone (∼800 °C, 1 bar) to produce lime (CaO) results in substantial carbon dioxide (CO_2(g)) emissions and energy use, i.e., ∼1 tonne [t] of CO₂ and ∼1.4 MWh per t of CaO produced. Here, we describe a new pathway to use CaCO₃ as a Ca source to make hydrated lime (portlandite, Ca(OH)₂) at ambient conditions (p, T)-while nearly eliminating process CO_2(g) emissions (as low as 1.5 mol. % of the CO₂ in the precursor CaCO₃, equivalent to 9 kg of CO_2(g) per t of Ca(OH)₂)-within an aqueous flow-electrolysis/pH-swing process that coproduces hydrogen (H_2(g)) and oxygen (O_2(g)). Because Ca(OH)₂ is a zero-carbon precursor for cement and lime production, this approach represents a significant advancement in the production of zero-carbon cement. The Zero CArbon Lime (ZeroCAL) process includes dissolution, separation/recovery, and electrolysis stages according to the following steps: (Step 1) chelator (e.g., ethylenediaminetetraacetic acid, EDTA)-promoted dissolution of CaCO₃ and complexation of Ca²⁺ under basic (>pH 9) conditions, (Step 2a) Ca enrichment and separation using nanofiltration (NF), which allows separation of the Ca-EDTA complex from the accompanying bicarbonate (HCO₃ ^-) species, (Step 2b) acidity-promoted decomplexation of Ca from EDTA, which allows near-complete chelator recovery and the formation of a Ca-enriched stream, and (Step 3) rapid precipitation of Ca(OH)₂ from the Ca-enriched stream using electrolytically produced alkalinity. These reactions can be conducted in a seawater matrix yielding coproducts including hydrochloric acid (HCl) and sodium bicarbonate (NaHCO₃), resulting from electrolysis and limestone dissolution, respectively. Careful analysis of the reaction stoichiometries and energy balances indicates that approximately 1.35 t of CaCO₃, 1.09 t of water, 0.79 t of sodium chloride (NaCl), and ∼2 MWh of electrical energy are required to produce 1 t of Ca(OH)₂, with significant opportunity for process intensification. This approach has major implications for decarbonizing cement production within a paradigm that emphasizes the use of existing cement plants and electrification of industrial operations, while also creating approaches for alkalinity production that enable cost-effective and scalable CO₂ mineralization via Ca(OH)₂ carbonation.

Publication types

Review