Integration of Ca-Looping Systems for CO2 Capture in Cement Plants

Experimental Investigation of Sulfation Phenomena in Calcium Looping Systems Integrated in Cement Plants

The sulfation phenomena of raw meal materials involved in calcium looping (CaL) applications to capture CO₂ from cement plants are investigated. The effects on sulfur capture capacity and reaction rates of different raw meals, temperatures, SO₂ concentration, and degree of belite conversions have been investigated using a thermogravimetric analyzer. SO₂ is shown to react with both free CaO and CaO in belite. An apparent reaction order of 0.8 and activation energies of 20.9 and 34.7 kJ/mol were estimated for cases with no-belite and belite formations, respectively. Results indicate that CaL systems for CO₂ capture will also remove SO₂ emissions in cement plants.

CO2 Capture at Medium to High Temperature Using Solid Oxide-Based Sorbents: Fundamental Aspects, Mechanistic Insights, and Recent Advances

Carbon dioxide capture and mitigation form a key part of the technological response to combat climate change and reduce CO₂ emissions. Solid materials capable of reversibly absorbing CO₂ have been the focus of intense research for the past two decades, with promising stability and low energy costs to implement and operate compared to the more widely used liquid amines. In this review, we explore the fundamental aspects underpinning solid CO₂ sorbents based on alkali and alkaline earth metal oxides operating at medium to high temperature: how their structure, chemical composition, and morphology impact their performance and long-term use. Various optimization strategies are outlined to improve upon the most promising materials, and we combine recent advances across disparate scientific disciplines, including materials discovery, synthesis, and in situ characterization, to present a coherent understanding of the mechanisms of CO₂ absorption both at surfaces and within solid materials.

Calcination kinetics of cement raw meals under various CO2 concentrations

The calcium looping CO₂ capture process, CaL, represents a promising option for the decarbonisation of cement plants, due to the intrinsic benefit of using the spent CO₂ sorbent as a feedstock for the plant.

Experimental carbonation of CaO in an entrained flow reactor

Performance of different CaO-based materials for full decarbonisation of gas streams in an entrained flow reactor as part of the calcium-looping process.

Characterization of a Marl-Type Cement Raw Meal as CO2 Sorbent for Calcium Looping

The use of cement raw meals as sorbent precursors for CO₂ capture can reinforce the synergies between the cement production process and calcium looping CO₂ capture technology. In this work, we measure the CO₂-carrying capacity of different calcined samples of a particular marl, which were obtained under very different calcination conditions and setups (a thermogravimetric analyzer, a drop tube furnace, and an industrial calciner). We find that the reactivity toward CO₂ of these calcined materials displays a strong sensitivity to the calcination conditions, in particular to calcination time. A pronounced competition between the belite (Ca₂SiO₄) formation reaction and the formation of free CaO needed for CO₂ capture is detected. As the calcination of the raw meal approaches flash conditions (i.e., >90% calcination conversion in less than 10 s), the belite formation is shown to be minimized, leading to sorbents with CO₂-carrying capacities of approximately 0.4 mol CO₂/mol CaO.