Mg-O-F Nanocomposite Catalysts Defend against Global Warming via the Efficient, Dynamic, and Rapid Capture of CO2 at Different Temperatures under Ambient Pressure

Samih A Halawy; Ahmed I Osman; Mahmoud Nasr; David W Rooney

doi:10.1021/acsomega.2c04587

Mg-O-F Nanocomposite Catalysts Defend against Global Warming via the Efficient, Dynamic, and Rapid Capture of CO₂ at Different Temperatures under Ambient Pressure

ACS Omega. 2022 Oct 19;7(43):38856-38868. doi: 10.1021/acsomega.2c04587. eCollection 2022 Nov 1.

Authors

Samih A Halawy¹, Ahmed I Osman^{1

2}, Mahmoud Nasr¹, David W Rooney²

Affiliations

¹ Nanocomposite Catalysts Laboratory, Chemistry Department, Faculty of Science at Qena, South Valley University, Qena83523, Egypt.
² School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, BelfastBT9 5AG, Northern Ireland, U.K.

Abstract

The utilization of Mg-O-F prepared from Mg(OH)₂ mixed with different wt % of F in the form of (NH₄F·HF), calcined at 400 and 500 °C, for efficient capture of CO₂ is studied herein in a dynamic mode. Two different temperatures were applied using a slow rate of 20 mL·min^-1 (100%) of CO₂ passing through each sample for only 1 h. Using the thermogravimetry (TG)-temperature-programed desorption (TPD) technique, the captured amounts of CO₂ at 5 °C were determined to be in the range of (39.6-103.9) and (28.9-82.1) mg_CO₂ ·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 CO₂ captured is slightly decreased to be in the range of (32.2-89.4) and (20.9-55.5) mg_CO₂ ·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 (ΔH) enthalpy changes corresponding to the desorption steps of CO₂ 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 CO₂ sorbents for climate change mitigation under ambient conditions.