Reactive Adsorption of NO2 on Copper-Based Metal-Organic Framework and Graphite Oxide/Metal-Organic Framework Composites

Composites of a copper-based metal-organic framework (MOF) and graphite oxide (GO) were tested for NO2 adsorption and retention of NO2 in dry and moist conditions. The samples were analyzed before and after exposure to NO2 by thermal analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, and adsorption of nitrogen at -196 degrees C. In dry conditions, the composites exhibit and enhanced NO2 breakthrough capacity compared to MOF and GO separately. This improvement is linked to the increased porosity and the reactive adsorption of NO2 on copper, which leads to the formation of bidentate and monodentate nitrate. Even though less NO2 is adsorbed in moist conditions than in dry ones the materials are more stable than in dry conditions and the NO retention is enhanced. Water in the challenge gas competes with NO2 to bind to copper and thus the number of reactive adsorption sites on which NO2 can be adsorbed/reacted decreases.