Development of Concentration-Swing Frequency Response Method for Mass Transfer Studies

The design and performance of separation and catalytic processes are highly dependent upon the understanding of the mass transfer inside the adsorbent and catalyst particles. Therefore, the fundamental knowledge of controlling mechanisms and rates is important for process design. Compared to other macroscopic techniques, frequency response (FR) has unique capability to determine dominating resistances by inducing parameter oscillations at various frequencies to help decoupling mass transfer resistances.

A new flow-through FR system, concentration-swing FR (CSFR), has been developed to study mass transfer at an increased range of temperatures and pressures for vapor and gas systems. This CSFR system is housed in an environmental chamber to allow temperature control from -60 ºC to 150 °C, and the sample has an additional heat element to allow in-situ regeneration up to 350 °C. The adsorption bed is designed to have flexibility to accommodate various amount samples, and capable of using ~mg samples for zero length column packing. The fast perturbation frequency can be detected up to 1 Hz to enable studies of relatively fast kinetics.

In this work we will present some examples of applying this CSFR technique to study mass transfer of water (vapor) and CO2 (gas) in zeolite LTA structure.