Microwave Swing Regeneration vs Temperature Swing Regeneration—Comparison of Desorption Kinetics

Abstract

This paper presents a comparison of microwave swing regeneration (MSR) and temperature swing regeneration (TSR) of acetone and toluene from 13X molecular sieves in terms of desorption kinetics and desorption efficiencies. The experiments were performed for two forms of the adsorbent: adsorbent bed consisting of spherical beads and adsorbent pressed in the shape of pastilles to allow for precise temperature measurement of the solid adsorbent. In TSR the adsorbent is heated by means of a hot inert gas stream whereas in MSR the adsorbent dissipates microwave energy into heat. It was found that MSR runs faster even when the adsorbent temperature is much lower than the gas temperature in TSR. This implies more efficient desorption due to less energy waste in the form of heat losses and less sensible enthalpy of purge gas stream since the total gas consumption is considerably decreased. The observed enhancement of microwave-driven desorption is more pronounced for the polar adsorbate (acetone) or high heat transfer resistances (pastilles). Finally, it was verified that microwaves do not affect the adsorption capacity of the molecular sieves after several consecutive adsorption–desorption cycles.