(126b) Modeling of Spatiotemporal Temperature Distribution in Hybrid Nanoscale Multifunctional Material for Desorption of CO2

The atmospheric CO₂ ppm levels have been rising alarmingly every year, increasing from less than 300 ppm in 1950 to a record 414 ppm in 2022. To prevent climate change and achieve the net-zero target by 2050, CO₂ emissions must be kept in check. This necessitates the development of highly-engineered solutions in the form of Negative Emission Technologies (NET) [1-3]. NETs mainly focus on capturing carbon dioxide either from point source (industrial emissions) or directly from the air. Among the available NETs, Direct Air Capture (DAC) has gained significant attention as it captures low concentrations of CO₂ directly from the atmosphere using chemical adsorbents [4]. Specifically, special hybrid nanoscale multifunctional materials are used as adsorbents in DAC to capture CO₂ because of their enhanced binding energy, mass transfer, and reaction kinetics [5]. However, regeneration of these materials requires a large amount of energy in the form of conventional heating for CO₂ desorption. As an alternative, microwave heating has been employed for adsorbent regeneration to reduce processing time and energy intensity of CO₂ desorption process. However, microwave heating poses a challenge of material degradation when exposed to repeated desorption cycles at high temperatures. Therefore, it becomes crucial to understand the temperature variation within the adsorbent.

Motivated by this objective, we model the spatiotemporal distribution of temperature inside a hybrid nanoscale multifunctional material during microwave heating. The material considered in this study is a Solvent Impregnated Polymer (SIP), which encapsulates Polyethylenimine with Nanoparticle Organic Hybrid Material (NOHM) [6]. A ferromagnetic additive is combined with the SIP to enhance targeted heating within the adsorbent. The temperature of the SIP placed inside the microwave is a critical parameter for optimally reducing material degradation. Thus, performing the spatiotemporal temperature analysis will help minimize material degradation and reduce material costs. During microwave heating, electromagnetic waves generate electric and magnetic fields [7-8]. These fields cause heat generation inside the adsorbent placed in the microwave, subsequently releasing the adsorbed CO₂ through the principle of targeted heating. The targeted heating at adsorbed sites (NOHM-activated) is caused by the presence of ferromagnetic additive (Fe₃O₄ nanoparticles), which results in hot spots inside the adsorbent. In our model, we solve heat diffusion and Maxwell's equations to analyze the temperature variation inside the SIP system during targeted heating occurs. Specifically, we use high-resolution modeling to estimate the spatiotemporal temperature distribution in a magnified polymer system with Fe₃O₄ nanoparticle at its core. This approach allows us to identify multiple hot spot regions inside the adsorbent and optimally control the temperature, enhancing the microwave heating process. The effectiveness of the developed model is verified by comparing the hot spots identified by the model with those detected in experiments. Further, the experimental proceedings will incorporate the temperature findings from the modeling to control the overall temperature during desorption in accordance with the regeneration temperature, thus reducing material degradation.

Literature cited:

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