Parametric Investigation of CO2 Desorption of Zeolite 13X Under Microwave Condition

Abstract

In this study, a parametric experimental analysis is performed to investigate the adsorption and desorption processes by evaluating CO2 concentration, sorbent temperature, adsorption, and desorption capacities, and desorption efficiency using Zeolite 13X with a modified multimode microwave oven. Four parameters varied: average microwave powers (336 to 504 W), gas flow rate (60 to 100 ml/min), regeneration temperature (80–120 °C) as well as the presence of moisture with an initial CO2 concentration of 20 %. This work is the first study that investigates these four main parameters’ effects together on the characteristics of CO2 desorption process of Zeolite 13X. While the adsorption was completed faster with higher flow rates with a faster breakthrough curve, the highest CO2 adsorbed amount was found at the lowest flow rates. The moisture effect on the adsorption capacity was also found to be negative with an adsorption capacity reduction of 20 % under wet conditions. The MW power was the key parameter since it controls the process (temperature), and the desorption stage in all conditions were completed faster with higher microwave power rates. However, low MW power always provided better results in terms of CO2 desorbed amount and desorption efficiency. Moreover, while higher flow rate speeded up the desorption process, it reduced the desorption efficiency. Moisture impact was found to be quite significant with a desorption efficiency reduction of 25 %. It was assumed that this reduction is attributed to the competition between the thermal desorption of CO2 and the absorption of CO2 by extra water in the system. Overall, while the amount of desorbed CO2 varied between 1.13 and 1.76 mmol CO2/g, the desorption efficiency changed from 51 % to 75 %.