The reversible cycling of CaO adsorbents to CaCO(3) for high-temperature CO(2) capture is substantially improved by mechanical treatment. The mechanical milling intensity and conditions of grinding (e.g., wet vs. dry, planetary vs. vibratory milling) were determined to be the main factors that control the effectiveness of the mechanochemical synthesis to enhance the recycling stability of the sorbents prepared. In addition, MgO was used as an example of an inert binder to help mitigate CaCO(3) sintering. Wet planetary milling of MgO into CaCO(3) allowed efficient particle size reduction and the effective dispersion of MgO throughout the particles. Wet planetary milling yielded the most stable sorbents during 50 cycles of carbonation-calcination.

We report the ultrasonic spray pyrolysis (USP) synthesis and characterization of composite calcium oxide-based sorbents for carbon dioxide capture. Inclusion of a small amount of Al 2 O 3 into the CaO matrix (as low as Al/Ca: 0.03) yielded significant enhancement of resistance to recycling degradation. The effective homogenous dispersion of additives in the CaO matrix and the relatively high surface area materials obtained via USP explain the sorbent's high performance. All materials were characterized by XRD, STEM, TEM, SEM, and TGA (for CO 2 uptake measurements). Two common phases of CaAl x O y , Ca 12 Al 14 O 33 and Ca 3 Al 2 O 6 , were formed during multiple cycles of calcination and CO 2 uptake.

No abstract

We report the preparation of calcium oxide (CaO)-based sorbents by ultrasonic spray pyrolysis (USP) with both experimental results and modeling of the sorption process. To mitigate CaO deactivation during carbonation/regeneration cycles, metal oxides with high melting temperatures were dispersed into CaO particles in this bottom-up synthetic method (USP), and their performance was experimentally characterized and evaluated over 50 cycles. The performance of synthesized sorbents was then compared to those expected from an unreacted shrinking core model. The model was able to predict the experimental results and provide an explanation for the effect of sintering and agglomeration on the performance of the sorbents through a variable effective diffusivity. Moreover, it was used to extrapolate sorbent performance over large numbers of cycles.

No abstract