(173d) Experimental Investigation of Microwave-Based Direct Air Capture Technology Using Zeolite 13X in a Fluidized Bed Reactor

Direct Air Capture (DAC) technology has recently considered as an attractive technology for reduction of CO₂emission from the atmosphere. However, the technology requires some development in terms of capital cost, thermal energy demand, and regeneration time. Several studies have researched temperature swing adsorption method in order to improve relatively low energy demand of sorbent materials in the regeneration process [1-3], while some other investigations concluded that the sorbents commonly applied for CO₂ capture technologies have low conductivity in heat transfer from the sorbent to the captured CO₂ [4-6]. This heat transfer limitation negatively impacts the energy demand of the system, capital cost, CO₂ purity and CO₂ productivity. Even if relatively higher desorption temperature can lead to get rid of the heat transfer limitation, regeneration temperature is restricted by the stability of sorbents [7,8]. For this reason, microwave-based DAC application can be considered to make the regeneration possible under low temperature condition removing heat transfer limitation due to volumetric heating. etc.

In this purpose, this study investigates experimental microwave-based low temperature DAC using Zeolite 13X as a solid sorbent in a different sized-fluidized bed reactor size (ID 16, 26, and 41 mm). Dry compressed air in Tuscaloosa, Alabama has been applied as air source throughout the adsorption process. In the regeneration process, a mono-mode solid state microwave generator has been adjusted to preset temperature (ranging from 33 ℃ to 60 ℃) and to initial power (switching from 5 W to 30 W). Various cycling experiments have been undertaken to identify regeneration performance in terms of adsorption capacity of the sorbent material in different cycles, energy consumption, regeneration time, desorption kinetics and CO₂ productivity. Additionally, since temperature homogeneity of the sorbent is challenging under microwave heating conditions, temperature distribution of Zeolite 13X with an average particle size of 217 microns has been measured using thermocouple, pyrometer, and IR camera during the regeneration stage. The results of this study prove that CO₂ regeneration is achievable at low temperature values under microwave heating in DAC application which also significantly contributes to reduction of energy demand of the system.

References

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