(537f) Vacuum Swing Adsorption for Carbon Dioxide and Water Vapor Capture for Environmental Control

Research into the capture and removal of CO₂ from air is performed on a wide variety of scales from rebreathers to industrial processes and a range of concentrations including low partial pressure (<500 ppm) like direct air capture (DAC), intermediate levels (1 to 3% CO2 in air) like removal of CO2 and water vapor from breathing loops, and high levels (3 – 15%) like capture of flue gas. Metal organic frameworks (MOFs) represent one promising means of selectively separating and capturing CO2 for a range of process streams and applications. In applications with long time scales and high concentrations of CO2, the high surface area of the MOFs allows extremely efficient capture of CO2. However, as the transport dynamics become more important in power or space-constrained systems, or in rapid flows of low partial pressure, capture becomes a more complex problem. This is compounded by the fact that MOFs are produced in small particle sizes of the order of 10s to 100’s of nanometers, which makes them difficult to integrate into conventional pressure swing units and prone to channeling, dusting, and high pressure drops.

Mainstream has developed and will discuss a polymeric-structured MOF adsorbent beads that maintains the high surface area and adsorption capacity of the MOF, while enabling simple drop-in replacement to conventional adsorbent bed systems. Data and results will be shared for the specific application of an optimized vacuum swing adsorption system for CO2 and moisture removal from a breathing loop (0.1 – 1% CO2). We discuss the effect of the MOF and high porosity bead formation on the pressure drop and adsorption kinetics for the selective capture and rapid removal of low partial pressures of CO2 and H2O. as compared to conventional zeolites. The effects of the MOF bead structure, MOF chemistry, polymer matrix and vacuum swing column and process conditions on the adsorption of CO2 at high flow rates, low partial pressures and sub ambient pressures will be discussed.