Influence of reaction temperature on mesoporous MgO based CO2 Capture

https://doi.org/10.3390/catal7040116

“It is fairly clear that the formation of intermediates is largely affected by the reaction temperatures. Therefore, SDS-assisted MgO particles have been methodically prepared under different temperatures at 100, 120, 140, and 160 °C, respectively, to further explore the influence of the reaction temperature. Figure 5a shows that the CO₂ uptake went up from 0.45 to 0.96 mmol g⁻¹ as the temperature increased from 100 to 120 °C and then declined from 0.96 to 0.15 mmol g⁻¹ from 120 to 160 °C. To better understand the circumstances, we also explored the structural changes of all samples synthesized in the temperature range of 100‒160 °C by XRD analyses. With the reaction temperature lower than 140 °C, all samples formed mainly MgO (JCPDS 45-0946) with some MgCO₃ (JCPDS 08-0479) impurity observed. As the diffraction peaks of MgCO₃ became stronger with elevated temperatures, the MgCO₃ content steadily increased. The 160 °C sample presented the majority phase of MgCO₃ with the sharp and intense peaks indicative of their highly crystalline nature. It is observed that MgO is the main components of the samples synthesized at low temperatures. It is interesting that specific surface area had good correlation with the CO₂ capture capacity (Table 5). For the 100 °C sample, the slow hydrolysis rate at lower temperatures is favorable to form large particles. The higher crystallinity gave rise to a decline in specific surface area, which shows good consistent with the CO₂ capture capacity. The samples fabricated at elevated temperatures are mainly MgCO₃. The specific surface area is rather low due to the high decomposition temperature, which coincides well with the CO₂ capture capacity.”

“Figure 5. (a) The influence of reaction temperature on the CO₂ capture capacity; (b) XRD spectra of MgO compounds at different reaction temperatures.”