Preparation and characterization of UiO-66-(OH)2/MWCNTs composites for CO2/N2 adsorption separation

Abstract

The increasing CO₂ concentration in the atmosphere can lead to climate change, and CO₂ capture technology is one of the most direct and effective means of reducing carbon emissions. In this study, a new composite was prepared in situ by loading multi-walled carbon nanotubes (MWCNTs) onto metal–organic frameworks (MOFs) to efficiently capture CO₂ in flue gas. The morphological states and pore structures of the composites were analyzed using characterization methods. The CO₂ adsorption properties of the composites were tested at 273 K and 298 K with different MWCNTs loadings. The optimal CO₂ adsorption quantities of the composite material were measured to be 4.4 and 5.75 mmol/g, respectively, which increased the adsorption capacity by 66.7 % and 55 %, respectively, compared with the parent material at a pressure of 1 bar. The CO₂/N₂ separation performance of the composites was examined using ideal adsorption solution theory calculations and dynamic adsorption breakthrough experiments. The stability of the composites was investigated by thermogravimetric analysis, acidification experiments, and cyclical adsorption–desorption experimentation. The UiO-66-(OH)₂/MWCNTs composites exhibited superior CO₂ adsorption–separation performance, thermal stability, acid resistance, and cycling stability. Therefore, the composite has potential applications in CO₂ capture separation technology.