Modeling of adsorption process on monolith adsorbents: A mini-review

Abstract

Monolith adsorbents are structured functional materials composed of numerous long, parallel, uniformly shaped (hexagonal, square, etc.) channels separated by thin walls. Honeycomb adsorbents have been widely applied in environmental remediation and gas-phase processes primarily because they offer efficient fluid–solid contact, small pressure drop at high flow rates, and superior mass transfer and diffusion compared to conventional fixed-bed adsorbents. Detailed modeling of adsorption on monolith adsorbents not only sheds light on the interconnections among physical and chemical phenomena during the adsorption and strategies to boost efficiency, but also facilitates sensitivity analysis on operating conditions and adsorbent design optimization. In this review, first some of the key factors that influence the gas-phase adsorption process including adsorbate properties, adsorbent characteristics, operating condition (temperature, humidity, and flow rate), and monolith adsorbent structure are reviewed. Next, a step-by-step modeling methodology to simulate the adsorption process on monolith adsorbents is put forward and discussed. The proposed methodology elucidates the steps to develop accurate models for mass transfer, momentum transfer, and adsorbent’s geometry. Furthermore, a number of simplifying assumptions are introduced and justified, which can significantly reduce the computational complexity and required resources in computational fluid dynamics (CFD) modeling. Finally, some remarks are made on the importance of modeling and optimization of monolith adsorbent structural designs prior to adsorbent fabrication and use to concurrently improve the adsorption performance and reduce the cost and time of adsorbent production in large scales.