Effect of Chemical and Physical Treatments on the Properties of a Dolomite Used in Ca Looping

Abstract

Four diverse microstructured MgO-stabilized CaO sorbents with varying mixing characteristics of Ca and Mg were obtained from untreated, hydrated, precipitated, and milled dolomite. Different morphological characterizations (thermal decomposition, phase composition, morphology, and nitrogen adsorption) were performed, followed by an analysis of 30 carbonation/calcination cycles in a fixed-bed reactor. The mixed metal oxide (CaO−MgO) in the fresh calcined dolomite transformed into separate crystals of CaO and MgO in the cycled sorbent and resulted in a relative decrease in the cyclic CO 2 capture capacity. Favorable structures (decreased crystallinity, increased porosity, and surface area) were generated by water hydration treatment, which was expected to enhance the recyclability, as suggested by some authors. However, this sorbent produced separate Mg and Ca as the major components, leading to a decrease in the CO 2 capture compared to fresh calcined dolomite. Complete segregation between Ca and Mg was observed upon precipitation treatment, which gave rise to the lowest cyclic CO 2 uptake. This segregation was eliminated by the final ball-milling treatment, thereby regaining the original reactivity. These results demonstrate the dominant role of the mixing of Ca and Mg on the cyclic CO 2 capture capacity of dolomite-based sorbents.

Acidification Optimization and Granulation of a Steel‐Slag‐Derived Sorbent for CO2 Capture

“…The presence of CaFe 2 O 4 and CaSiO 3 will affect the durability of the sorbents due to their low resistance to sintering. In contrast, MgO, with a sintering temperature of 1289 °C , , can effectively mitigate the rapid deactivation of the steel‐slag‐derived sorbents.…”

CO2 Capture Performance of Gluconic Acid Modified Limestone-Dolomite Mixtures under Realistic Conditions

“…35 A number of studies have attempted to employ treated/synthetic dolomite-based materials. Thus,Wang et al 36 and Sánchez-Jiménez et al 37 reported that dry ball-milling slightly enhanced the cyclic conversion of dolomite-derived sorbents.…”

Blending Wastes of Marble Powder and Dolomite Sorbents for Calcium-Looping CO2 Capture under Realistic Industrial Calcination Conditions

“…The presence of chemical elements such as Mg, Al and Si, during the carbonation-calcination cycles influences the skeleton/microstructure of the calcined sorbent, which hinders aggregation or sintering of CaO crystallites and helps in preserving the nanocrystalline CaO structure [46]. Some approaches have been carried out to improve the CO 2 capture by dolomitic carbonates, such as acid acetic pre-treatment [47] and two-step calcination under N 2 and CO 2 atmosphere to modify the sorbent microstructure [48], and ball milling of dolomite [49], even with water [50] or with ice and water to regenerate the dolomite and increase the CO 2 carrying capacity through the elimination of CaO and MgO segregation after cyclic carbonation-calcination cycles [51]. However, more detailed studies are still necessary to understand the role of MgO on the enhancement of the stability and multicycle carrying capacity performance observed for this alternative natural CaO-based sorbent, especially under a realistic industrial calcination gas atmosphere with a high concentration of CO 2 .…”