Table 3 shows that 70% of the adsorbed CO2/CH4 was recovered by microwave heating while only 57% by conductive heating.In microwave desorption, an average net energy of 0.67 kJ/g was consumed to achieve such desorption, however, approximately 7.7 kJ/g was consumed in the case of conductive heating.
On average 25 J of microwave energy and 348 J of conductive energy are needed to release 1 mL of gas adsorbed on Na-ETS-10.Throughout the five adsorption–regeneration cycles, conductive heating requires 14 times more energy than microwave heating in order to desorb the same volume of gas. The higher energy requirement in conductive heating is due to high heat loss as discussed in Section 3.1. Fig. 7 illustrates the consistency in energy consumption over five cycles of CO2/CH4 desorption for microwave heating and conductive heating.
Table 4 summarizes the purity of the recovered CO2/CH4 gas for these two heating techniques over five cycles of adsorption/desorption. Based on GC–TCD analysis, the purity of the gas desorbed by microwave heating consisted of 82–83% CO2 and 17–18% CH4 while the purity of the gas desorbed by conductive heating contained 81–81.8% CO2 and 18–19% CH4.