(563a) Development and Demonstration of Gas Separation By MOF Enabled Vacuum Swing Adsorption System

Adsorbent based separations using vacuum- or pressure-swing adsorption can drastically reduce capital and operating expenses over cryogenic distillation, especially at smaller scales. However, in order for vacuum swing adsorption (VSA) to be viable at-scale, it requires adsorbents with extremely high selectivity for the target species and sufficient capacity or permeability to achieve industrial relevance. Proper adsorbents have the ability to capture and concentrate even dilute gases to produce high purity storage. Metal-organic frameworks (MOFs) are a next-generation adsorbent that have demonstrated extreme effectiveness for selective adsorption but are traditionally held back by their nanometer- to submicron-scale particle powders, making them impractical to integrate into industrial sized processes. Mainstream has developed and presented the results of our highly scalable and tunable process to produce high porosity-engineered MOF-polymer beads. This platform approach has been demonstrated as applicable to a wide range of MOF materials with bead sizes controllable down to 0.1 mm with high MOF loading, no loss of active MOF surface area, high stability, low-pressure drop, and no dusting.

An automated bench-scale MOF-VSA system has been developed and demonstrated for CO₂ capture from air and separation and capture of xenon and krypton at <1,000 ppm concentrations. Discussion will focus on the analysis of the key operational parameters including residence time distribution, pressure drop modeling (i.e., Ergun Relationship), film resistance and intraparticle diffusion, and scaling parameters culminating in a process design that details separation and captured gas purity as a function of steps and technoeconomic analysis. Trade-offs in cost, selectivity, and capacity as a function of temperature indicate the optimal operation conditions are frequently not when the adsorbent has highest selectivity, but is dependent on cyclical performance and system design.