Topic
Calcium oxide
About: Calcium oxide is a research topic. Over the lifetime, 7600 publications have been published within this topic receiving 66104 citations. The topic is also known as: caustic lime & quicklime.
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TL;DR: In this article, the composition and microstructure changes of cement pastes when heating until 620 °C and cooling afterwards have been monitored on site by neutron diffraction, and the residual state of the samples has also been studied by mercury intrusion porosimetry (MIP) and thermogravimetry analysis (TGA).
217 citations
TL;DR: In this article, the carbonation rate of 15−20 μm, nonporous, calcium oxide crystals has been studied over a temperature range of 550−1100 °C and a CO2 pressure range of 1−11.7 atm.
Abstract: The carbonation rate of 15−20 μm, nonporous, calcium oxide crystals has been studied over a temperature range of 550−1100 °C and a CO2 pressure range of 1−11.7 atm. At temperatures greater than 600 °C, the carbonation rate decreases more rapidly with time than would be expected from diffusion through a uniform product layer and the activation energy is initially low but increases with conversion. The product layer consists of crystalline grains, and these product layer grains grow by coalescence from less than one μm diameter to the approximate dimension of the particle. The carbonation rate can be described by a model where CO2 pressure-independent grain boundary diffusion and diffusion through the carbonate crystals act in parallel. The relative importance of bulk diffusion through the product layer crystals increases with time relative to transport through the grain boundaries and has an effective activation energy of 57 kcal/mol. Diffusion through the crystal boundaries has low activation energy and l...
216 citations
TL;DR: The sorbent CG- CaO showed a much lower decomposition temperature and higher predicted residual conversion after prolonged cycles, compared with CC-CaO.
Abstract: A screening of potential calcium precursors for the production of CaO sorbents for CO2 capture at high temperature was conducted in this work. The precursors studied include microsized calcium carbonate (CC-CaO), calcium hydroxide (CH-CaO), nanosized (<70 nm) calcium carbonate (CC70 nm-CaO), nanosized (<160 nm) calcium oxide (CaO160 nm-CaO), calcium acetate hydrate (CA-CaO), calcium l-lactate hydrate (CL-CaO), calcium formate (CF-CaO), calcium citrate tetrahydrate (CCi-CaO), and calcium d-gluconate monohydrate (CG-CaO). The capture capability of these sorbents was investigated using a thermogravimetric analyzer (TGA) for multiple capture cycles. CG-CaO exhibited the best capacity for capturing CO2 with a 1-min conversion of 65.9% and a 30-min conversion of 83.8% at the ninth cycle. Subsequently, a further parametric study was conducted to examine the effect of reaction conditions such as reaction temperature (550−750 °C) and CO2 gas concentration (1−15%) on the capture capacity of CG-CaO. The sorbent CG-C...
211 citations
TL;DR: In this article, the nature of adsorption states of CO sub 2 on mixed Mg/Ca oxide catalysts was investigated by FTIR spectroscopy, and surface basicity was quantitatively measured by the wavenumber difference of symmetric and asymmetric carbonate absorption bands.
Abstract: The nature of adsorption states of CO{sub 2} on mixed Mg/Ca oxide catalysts was investigated by FTIR spectroscopy. At room temperature, the unidentate is predominantly formed besides bicarbonate. On CaO-rich catalysts additional structures were detected and attributed to bridging carbonate and linearly adsorbed CO{sub 2}. Desorption behavior of these species is discussed in dependence on temperature. Surface basicity was quantitatively measured by the wavenumber difference of symmetric and asymmetric carbonate absorption bands and related to catalytic activity for oxidative coupling of methane. 22 refs., 6 figs., 2 tabs.
206 citations
TL;DR: In this paper, a complete characterization of lime cycle transitions is described using X-ray diffraction by powder to accomplish phase identification and scan electron microscopy was done to examine the morphology, topology, crystal structure, and crystalline growth habit.
Abstract: In this paper a complete characterization of lime cycle transitions is described. CaCO3 was collected from a Mexican mine and was processed to obtain Ca ( OH ) 2 through CaO. When the calcium hydroxide interacted with the CO2 in the air forming CaCO3 , the lime cycle was completed. Crystal structure and spectroscopy characterization was carried out to get the knowledge of lime cycle CaCO3 →CaO→Ca ( OH ) 2 → CaCO3 deeply. The changes in the crystalline structures were described using X-ray diffraction by powder to accomplish phase identification. Scanning electron microscopy was done to examine the morphology, topology, crystal structure, and crystalline growth habit. Dynamic light scattering was used to determine the particle-size distribution of Ca ( OH ) 2 . Fourier-transform infrared was done to identify molecules and atomic bonds. Finally, inductively coupled plasma-mass spectrometry was done to get quantitative analyses. These results are a contribution to the restoration and construction industry fi...
201 citations