Influence of ethanol to water ratio on mesoporous MgO development for CO2 Capture

https://doi.org/10.3390/catal7040116

“Apparently, the ethanol to water ratio is one of the key parameters that influences the CO₂ capture performance of MgO samples. Figure 2a shows the CO₂ capture capacity of the synthesized MgO with different ratios at 300 °C. Based upon the data, one can see that the CO₂ uptake increased with the increase in water content. The decline in CO₂ uptake with the addition of ethanol may be attributed to a slow hydrolysis rate and a slightly lower solubility of SDS. The structural changes of MgO particles were also investigated by XRD analyses, as shown in Figure 2b. All diffraction peaks of the samples can be indexed to the MgO (JCPDS 45-0946). Notably, two small characteristic peaks of magnesium carbonate (MgCO₃) at 2θ ≈ 32.20° and 53.35° (JCPDS 08-0479) were observed, indicating a little MgCO₃ was incorporated in MgO. When the ethanol content was high, a slower hydrolysis rate and a slightly lower solubility of SDS were favorable for the growth of MgO with a higher crystalline degree. The slight shift to a higher angle might be due to the contraction of the lattice constant when the crystalline degree was high [41,42]. It should be noted that the specific surface area increased steadily from 58.7 to 321.3 m² g⁻¹ with the rise in water content, while the average pore size is on a gradual decline from 23.52 to 1.88 nm, which is consistent with the CO₂ uptake data, as shown in Table 2.”

“Figure 2. (a) The influence of ratios of ethanol and water on the CO₂ capture capacity; (b) XRD spectra of MgO compounds with different ratios of ethanol and water.”