Synthetic Ca‐based solid sorbents suitable for capturing CO₂ in a fluidized bed

Abstract

Coprecipitation and hydrolysis of CaO have been employed to produce Ca-based synthetic sorbents suitable for capturing CO 2 in a fluidized bed. Their composition, CO 2 uptake, volume in small pores (2-200 nm) and resistance to attrition were measured and compared to those of limestone and dolomite. Sorbents produced by hydrolysis showed the highest uptake and resistance to attrition. After 20 cycles of carbonation and calcination, two sorbents exceeded the uptake of both limestone and dolomite, when subjected to the same regimes of reaction. A sorbent's uptake of CO 2 was shown to be determined by the volume in pores narrower than ∼200 nm.On a eu recoursà la co-précicipation età l'hydrolyse de CaO pour produire des sorbants convenantà la capture de CO2 dans un lit fluidisé. Leur composition, le retrait de CO 2 , le volume dans les petits pores (2-200 nm) et la résistanceà l'attrition ontété mesurés et comparésà ceux du calcaire et de la dolomite. Les sorbants produits par hydrolyse montre l'absorption et la résistanceà l'attrition les plusélevées. Après 20 cycles de carbonisation et calcination, deux sorbants dépassent la capacité de retrait du calcaire et de la dolomite, lorsqu'on applique les mêmes régimes de réaction. On montre que le retrait de CO 2 par un sorbant est déterminé par le volume des pores plusétroit que 200 nm.

Multicyclic conversion of limestone at Ca-looping conditions: The role of solid-sate diffusion controlled carbonation

“…The evolution of CaO conversion would be strongly affected whenever solid-state diffusive carbonation, which is a crystal structure sensitive property, is relevant. For example, CaO/mayenite polycrystalline composites are seen to exhibit reactivation similarly to pretreated limestones [47][48][49][50][51] even under severe calcination conditions [51]. As well known, solid-state diffusion is enhanced in polycrystalline materials as compared to pure crystals because of the accelerated diffusion along the grain boundaries [52].…”

The calcium looping cycle for CO2 capture from power generation, cement manufacture and hydrogen production

“…calcium acetate, calcium ethanoate (Lu et al, 2006;Lu, H. et al, 2008;Liu et al, 2010a) with particular success using a MgO support (Liu et al, 2010b) to similarly enhance the reactive surface area; dispersal of CaO within an inert porous matrix such as mayenite (Li et al, 2005;Li et al, 2006;Pacciani et al, 2008a) to improve mechanical stability; and use of cementitious binders (Manovic and Anthony, 2009a; to improve mechanical stability. Sorbent reactivity can be periodically improved by hydration of calcined sorbent, though this is often at the expense of mechanical strength of the sorbent (Hughes et al, 2004;Fennell et al 2007b;Manovic and Anthony, 2007;Manovic and Anthony., 2008a;Sun et al, 2008;Zeman, 2008).…”

CO2 capture by calcium aluminate pellets in a small fluidized bed

“…One of the most studied supports is Al2O3, which thermodynamically will form the inert-to-CO2 mayenite (Ca12Al14O33) upon reaction with CaO [12,13], though there are kinetic reasons why this may not form rapidly -or, e.g., in the first few cycles of carbonation and calcination [14]. Other proposed supports include: MgO [15,16], in analogy with enhancements seen with natural dolomite over natural limestone [17], which does not form mixed metal oxides with CaO [3]; SiO2, which forms mixed metal oxides with CaO [18], has a relatively low sintering temperature, but phase change materials have the potential to increase the porosity upon calcination [19]; amongst others such as ZrO2, CeO2, TiO2/CaTiO3, CuO, CoO, BaO and Cr2O3 [3,4].…”