Enhancing CO₂ Adsorption Capacity and Cycling Stability of Mg-MOF-74

Mitigation of carbon dioxide emitted from burning fossil fuels is essential to overcome climate change issues. Adsorption technology could significantly help in capturing CO₂ and, thereby minimizing global warming with low-cost penalties. Mg-MOF-74 was reported as a distinguished adsorbent that has high adsorption capacity at flue gas conditions. In the present study, an improvement of crystallinity, porosity, and capacity of Mg-MOF-74 was investigated through controlling the heat surface area of the sample solution during the synthesis process. The results showed that the increase in the heat surface area during the synthesis process increased BET surface area and pore volume of the adsorbent by 38% and 44%, respectively, over those obtained by the reported method in the literature. For additional improvement in the cyclic CO₂ uptake, multi-walled carbon nanotubes (MWCNT) were incorporated with Mg-MOF-74. The adsorption cycling stability was performed using three techniques: temperature swing adsorption (TSA), vapor swing adsorption (VSA), and temperature vacuum swing adsorption (TVSA). It was observed that the incorporation of MWCNT with Mg-MOF-74 resulted in higher CO₂ recycling capacity (14.4%) using thermal-based regeneration processes (i.e., TSA and TVSA) due to the enhancement in the thermal transport properties of the new composite (MWCNT/Mg-MOF-74).