Cement clinker precursor production in an electrolyser

Abstract

The manufacture of cement is the single largest industrial source of CO_2(g) emissions into the atmosphere. We report here an electrochemical flow reactor (electrolyser) that continuously converts limestone (CaCO_3(s)) into Ca(OH)_2(s) at a high rate of product formation (486 mg h⁻¹ at 100 mA cm⁻²). The Ca(OH)_2(s) product (slaked lime) is a chemical precursor to cement clinker, the main component of Portland cement, and other cement varieties. This three-compartment electrolyser operates with ∼100% current efficiency at a cell voltage of 2.9 V and generates pure O_2(g), H_2(g), and CO_2(g) streams that can be utilized downstream without purification. To demonstrate this feature, we feed the CO_2(g) released from limestone directly to a second electrolyser that valorizes CO_2(g) into higher value carbon-containing products (e.g., CO). A preliminary life-cycle analysis indicates that the proposed electrochemical process can decrease the amount of CO₂ emitted per tonne of cement by 75% and achieve cost-parity with incumbent cement manufacturing processes.