Development of a new CO2 capture process with vacuum-assisted calcination for the direct production of pure CO2

The urgent need to achieve net-zero CO 2 emissions by mid-century has intensified research into cost-effective and scalable carbon capture technologies. Calcium Looping is a promising high-temperature process for CO 2 separation, although its widespread deployment is hindered by the high energy demand of CaCO 3 calcination and the complexity of heat management in packed-bed systems. This work presents the first experimental demonstration of a novel Calcium Looping process that integrates vacuum-assisted calcination to enable autothermal operation and the direct production of ultra-pure CO 2 without downstream purification. When pressure during calcination is reduced to below 0.1 bar, the thermal energy stored in solids during the preceding carbonation step drives CaCO 3 decomposition at significantly lower temperatures. As a result, a CO 2 stream of near 100% purity is obtained. Laboratory-scale tests in packed-bed reactors at TRL3-4 confirm that the process achieves capture efficiencies above 95% for gas streams containing 15–50 vol% CO 2 . Peak temperatures exceeding 800 °C are reached during carbonation, followed by effective regeneration under vacuum. Additional experiments demonstrate the benefits of moderate pressurization (up to 4 bar) during the CO 2 capture stage. The integration of chemical looping combustion (CLC) stages using CuO-based oxygen carriers provides in situ heat, enabling cyclic operation and overcoming thermodynamic limitations for low-CO 2 feeds. • Novel Calcium Looping process with vacuum-assisted calcination for CO 2 capture. • The process produces ultra-pure CO 2 without downstream purification steps. • CO 2 capture efficiencies above 95% achieved for streams containing 15–50 vol% CO 2 . • Moderate pressurization (2–4 bar) allows higher CO 2 capture efficiencies. • Chemical looping combustion provides heat in situ to optimize cyclic operation.