A Review of CO2 Adsorption From Ambient Air (Direct Air Capture)

Shabbani, Hind Jihad Kadhim

doi:10.30772/qjes.v13i1.644

	A Review of CO2 Adsorption From Ambient Air (Direct Air Capture)
Al-Qadisiyah Journal for Engineering Sciences
Volume 13, Issue 1, March 2020, Pages 1-6 PDF (1.09 M)
DOI: 10.30772/qjes.v13i1.644
Author
Hind Jihad Kadhim Shabbani
Department of Materials Engineering, University of Al-Qadisiyah, Iraq
Abstract
Direct Air Capture (DAC) has risen in the past decade as a promising choice to remove CO₂ directly from ambient air. Although there are many technologies like pre-combustion, post-combustion and oxy-combustion to mitigate the emissions of CO₂, there is still a need for a better or a complementary technology in controlling these emissions. Even though, there are many options for adsorbents that can be used, metal-organic frameworks (MOFs), which are hybrid materials with a crystalline structure, tunable pores, and high surface area, have risen as a promising candidate. Functionalizing MOFs with amine groups will greatly enhance their capacity towards CO₂, like mmen-M₂ (dobpdc) (M=Mg, Fe, Mn, Zn, Co). These adsorbents show S-shaped adsorption isotherms and have a very high affinity to CO₂ under atmospheric conditions, due to the cooperative insertion of CO₂ into mmen-M₂ (dobpdc) that leads to their unique adsorption isotherms. The energy required to regenerate these materials using small heat variations makes a better choice than aqueous amines. This mechanism has been studied by using X-Ray Diffraction (XRD) and spectroscopy experiments. Furthermore, a thermodynamic study has been reviewed to understand the mechanism through which CO₂ is inserted into the diamine bond. These materials are a promising choice for the removal of CO₂directly from the atmosphere and require more future research.
Keywords
Adsorption; Adsorbent; Isotherms

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