Indirect and direct microwave regeneration of Na-ETS-10

•Two microwave assisted methods were assessed for the regeneration of ETS-10 adsorbents.•Water desorption was compared with direct microwave regeneration for CO2/CH4 streams.•Direct microwave regeneration appears to be the most promising method.

Indirect and direct microwave regeneration were assessed as potential techniques for desorbing a CO2/CH4 mixture from Na-ETS-10. Indirect microwave regeneration consists of desorption with water followed by microwave drying, while direct microwave regeneration consists of constant power microwave heating. Five adsorption–desorption cycles were completed to determine and compare the swing capacity, net energy consumption, and gas recovery obtained with these two regeneration techniques. During indirect microwave regeneration the swing capacity of Na-ETS-10 was stable at 0.3 mmol/g, with the exception of the first cycle where it reached 1.6 mmol/g. The first cycle swing capacity decreased however, by fivefold during the subsequent desorption cycles. During direct microwave regeneration, the swing capacity remained stable at 0.7 mmol/g over all five consecutive cycles. On average, 2.46 KJ and 0.32 KJ were consumed during regeneration of 1 g of Na-ETS-10 using indirect and direct microwave regeneration, respectively. With the exception of the first cycle, gas recovery for indirect microwave regeneration was only 20%. In contrast, an average of 50% gas recovery was achieved by direct microwave regeneration.