(663d) CO2 and Water Adsorption on Seeded Growth of Mg-MOF-74 on Carbon-Nanotubes

Increased atmospheric CO₂ concentrations result in increased demand for novel and efficient CO₂ control technologies. Metal Organic Frameworks (MOFs) have recently attracted research interests due to their tailorable porous structure and potential application as novel adsorbents. The presence of open metal sites in some MOFs fortifies their adsorption sites, which is favorable for CO₂ capture. In this research, the adsorption performance of Mg-MOF-74 is enhanced by incorporating MOF on a membrane surface. Mg-MOF-74 was synthesized by solvothermal method and seeded on the surface of plasma treated carbon nanotube bucky paper which has demonstrated a superior CO₂ adsorption. The plasma treatment was conducted in either O₂/Ar or NH₃ gas flows. All samples were characterized using XRD, XPS, SEM, and CO₂ volumetric adsorption. XRD results show identical pattern for Mg-MOF-74 grown on CNT and Mg-MOF-74 alone, confirming the intact crystalline structure of MOF. XPS measurements illustrates that plasma treatment with O₂/Ar can yield samples with higher wettability which is favorable for further surface modification and increases affinity towards water vapor by anchoring hydroxyl functional group on the surface. The incorporation of MOF on CNT increased the CO₂ adsorption performance of MOF. The highest CO₂ adsorption capacity of 5.6, and 34.7 mmol/g was obtained for Mg-MOF-74, and Mg-MOF-74-CNT, respectively. Maximum water adsorption capacity of 9.0 and 20.6 mmol H₂O/g were obtained for Mg-MOF-74 and Mg-MOF-74-CNT, respectively. Comparing CO₂ and H₂O isotherms for prepared samples demonstrates that generally the seeded growth Mg-MOF-74 on CNT-BP performed better than Mg-MOF-74.