Mg–O–F Nanocomposite Catalysts Defend against Global Warming via the Efficient, Dynamic, and Rapid Capture of CO ₂ at Different Temperatures under Ambient Pressure

Abstract

The utilization of Mg–O–F prepared from Mg(OH) ₂ mixed with different wt % of F in the form of (NH ₄F·HF), calcined at 400 and 500 °C, for efficient capture of CO ₂ is studied herein in a dynamic mode. Two different temperatures were applied using a slow rate of 20 mL·min ^–1 (100%) of CO ₂ passing through each sample for only 1 h. Using the thermogravimetry (TG)-temperature-programed desorption (TPD) technique, the captured amounts of CO ₂ at 5 °C were determined to be in the range of (39.6–103.9) and (28.9–82.1) mg _{CO 2} ·g ^–1 for samples of Mg(OH) ₂ mixed with 20–50% F and calcined at 400 and 500 °C, respectively, whereas, at 30 °C, the capacity of CO ₂ captured is slightly decreased to be in the range of (32.2–89.4) and (20.9–55.5) mg _{CO 2} ·g ^–1, respectively. The thermal decomposition of all prepared mixtures herein was examined by TG analysis. The obtained samples calcined at 400 and 500 °C were characterized by X-ray diffraction and surface area and porosity measurements. The total number of surface basic sites and their distribution over all samples was demonstrated using TG- and differential scanning calorimetry-TPD techniques using pyrrole as a probe molecule. Values of (Δ H) enthalpy changes corresponding to the desorption steps of CO ₂ were calculated for the most active adsorbent in this study, that is, Mg(OH) ₂ + 20% F, at 400 and 500 °C. This study’s findings will inspire the simple preparation and economical design of nanocomposite CO ₂ sorbents for climate change mitigation under ambient conditions.