Sulfation rates of cycled CaO particles in the carbonator of a Ca-looping cycle for postcombustion CO2 capture

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.

Solid-Waste-Derived Carbon Dioxide-Capturing Materials

Solid sorbents are considered to be promising materials for carbon dioxide capture. In recent years, many studies have focused on the use of solid waste as carbon dioxide sorbents. The use of waste resources as carbon dioxide sorbents not only leads to the development of relatively low-cost materials, but also eliminates waste simultaneously. Different types of waste materials from biomass, industrial waste, household waste, and so forth were used as carbon dioxide sorbents with sufficient carbon dioxide capture capacities. Herein, progress on the development of carbon dioxide sorbents produced from waste materials is reviewed and covers key factors, such as the type of waste, preparation method, further modification method, carbon dioxide sorption performance, and kinetics studies. In addition, a new research direction for further study is proposed. It is hoped that this critical review will not merely sum up the major research directions in this field, but also provide significant suggestions for future work.

Renedo M. Sulfation and Carbonation Competition in the Treatment of Flue Gas from a Coal-Based Power Plant by Calcium Hydroxide

In this work, a gas containing CO2 and SO2 at the usual concentrations on the coal combustion flue gas reacted with calcium hydroxide to evaluate and quantify the influence of SO2 on the CO2 capture and vice versa. This influence was quantified with a continuous gas analyzer and by thermogravimetry (TG). Results show that the CO2 retained increases in general as its concentration does and decreases as the SO2 concentration increases. A similar behavior was found for the SO2 retention at different CO2 concentrations being more relevant the influence of the presence of SO2 on the CO2 capture than the opposite one. Results suggest that for a high CO2 capture, SO2 should be eliminated previously. With respect to the reaction process it was found that the desulfurization product clearly identified was CaSO3·½H2O; in the reaction between Ca(OH)2 and CO2, CaCO3 is mainly obtained, the complex CaO·CO2 being another possible product synthesized in low amount. Gas analyzer shows that SO2 and CO2 react simultaneously and that a part of the CaCO3 reacts with the SO2 and releases CO2. Sulfation values calculated by TG and from the gas analyzer are very similar but the amount of CO2 captured is not possible to know clearly by TG due to the synthesis and decomposition of CaCO3 during the process. The study of the evolution of the sorbent porosity in the process reveals that the presence of both acid gases produces a lower blockage of the pores than when only one gas is present probably due to the generation of new pores in the reaction of CaCO3 and SO2.