In Situ Angstrom-to-Micrometer Characterization of the Structural and Microstructural Changes in Kaolinite on Heating Using Ultrasmall-Angle, Small-Angle, and Wide-Angle X-ray Scattering (USAXS/SAXS/WAXS)

Abstract

Synchrotron-based in-operando multi-scale X-ray scattering analyses are used to connect microstructural changes to phase changes in kaolinite on heating from 30 °C to 1150 °C. Combined ultra-small-angle and small-angle X-ray scattering (USAXS and SAXS) data are modeled to determine the hierarchical morphology of kaolinite comprising nano-scale interlayer pores, meso-scale pores, and larger interparticle voids, while wide-angle X-ray scattering (WAXS) data reveal the simultaneous evolution of molecular phases in kaolinite. We found that the transformation of kaolinite to metakaolin corresponds to the disappearance of nano-scale porosity, and the onset of sintered phases such as mullite consistent with the overall reduction in porosity. The emergence of nanoscale particulate features on heating above 900 °C corresponds to the onset of sintered phases such as spinel and mullite. This study illustrates the application of multi-scale X-ray scattering measurements to connect the thermally induced phase changes with changes in pore structure and fine morphology evolution.

Phase Evolution and Textural Changes during the Direct Conversion and Storage of CO2 to Produce Calcium Carbonate from Calcium Hydroxide

“…The characteristic peak of calcium hydroxide which corresponds to the (1 0 0) reflection at q = 2.024 Å −1 undergoes significant changes with continuous CO 2 flow as the temperature increases ( Figure 2) [40]. The shift in the characteristic peak to lower q or larger d values corresponds to thermal expansion, as reported in previous studies [10,28,41]. Tracking the changes in the integrated intensity of calcium hydroxide peak yields important insights into the onset of carbon mineralization behavior.…”

“…In this paper, the evolution of calcium carbonate phases from calcium hydroxide and the corresponding changes in the roughness of the pore-solid interface are investigated using in-operando synchrotron ultrasmall, small, and wide angle X-ray scattering (USAXS/SAXS/WAXS) measurements [6,8,10,11,[28][29][30][31][32]. Wide angle X-ray scattering measurements provide unambiguous insights into the structural changes, while ultrasmall and small angle X-ray scattering measurements reveal the changes in the textures of the pore-solid interface during the carbon mineralization of calcium hydroxide to produce calcium carbonate.…”

Phase Evolution and Textural Changes during the Direct Conversion and Storage of CO₂ to Produce Calcium Carbonate from Calcium Hydroxide

“…The characteristic peak of calcium hydroxide which corresponds to the (1 0 0) reflection at q = 2.024 Å -1 undergoes significant changes with continuous CO2 flow as the temperature increases ( Figure 2) [40]. The shift in the characteristic peak to lower q or larger d values corresponds to thermal expansion, as reported in previous studies [10,28,41]. Tracking the changes in the integrated intensity of calcium hydroxide peak yields important insights into the onset of carbon mineralization behavior.…”

“…In this paper, the evolution of calcium carbonate phases from calcium hydroxide and the corresponding changes in the roughness of the pore-solid interface are investigated using inoperando synchrotron ultra-small, small, and wide angle X-ray scattering (USAXS/SAXS/WAXS) measurements [6,8,10,11,[28][29][30][31][32]…”

Multiscale X-Ray Scattering for Probing Chemo-Morphological Coupling in Pore-to-Field and Process Scale Energy and Environmental Applications

“…Other studies quantified the porosity in limestone and sandstone using ultra-small and small angle neutron scattering (USANS/SANS) measurements supported by complimentary electron microscopy imaging [12,13]. With the recent interest in energy recovery from unconventional formations, the non-invasive characterization of the porosity in shales [14][15][16] and its constituents such as clays [17][18][19] using USAXS/SAXS has received increased attention.…”