https://doi.org/10.1002/cssc.202002078
“For instance, synchrotron-based studies under reaction conditions (in-situ) or after having exposed the materials to reaction conditions (ex-situ) have been carried out to identify relationships between the porosity, crystallite size and the CO2 uptake performance of CaO-based sorbents.35–37 For example, Benedetti et al. applied ex-situ synchrotron small angle X-ray scattering (SAXS), ultra small angle X-ray scattering (USAXS) and wide angle X-ray scattering (WAXS) on CaO-based sorbents to study their microstructural features (Figure 3a).35 Specifically, SAXS and USAXS probed the sorbents’ microstructural properties such as pore size distribution, specific surface area and pore radius of gyration. (U)SAXS can be performed simultaneously with WAXS, from which the crystalline phases of a given material can be identified. The ex-situ investigation of the micro-textural properties in a series of CaO samples with different degrees of carbonation showed that the surface area decreases linearly with increasing CaO conversion, confirming the important role of the CaO surface area on the overall CO2 capacity of a sorbent. However, the relevance of larger (>100 nm) pores for the CO2 uptake performance was not elucidated. ”
“Figure 3 (a) Illustration of the methodology used to quantify changes in pore size distribution during carbonation of CaO by USAXS-SAXS. Reprinted with permission from Ref. [35]; copyright Elsevier, 2019. (b) Visualization of the macro-pores in a CaO particle prior to and after carbonation. Adapted with permission from Ref. [36]; copyright Royal Society of Chemistry, 2016.”