(371a) Guide to COF Adsorbent for Ammonia-based Green Hydrogen with Multi-scale Evaluation Approach
AIChE Annual Meeting
Tuesday, November 15, 2022 - 3:30pm to 5:00pm
As the first attempt of the adsorbent discovery for such green H2 separation, in this study, we explore 648 covalent organic frameworks (COFs) because COFs have high potential as adsorbents in terms of their mechanical and chemical durability . In order for the practical and efficient evaluation of the adsorbents, we propose a multi-scale adsorbent screening approach, which includes both molecular and process scale evaluation. In the molecular scale evaluation, the adsorption isotherm curves of the COFs are calculated based on the grand canonical Monte Carlo (GCMC) simulations. The calculated isotherm curves, in the process scale evaluation, are employed to estimate the H2 recovery and H2 purity of the PSA process as performance indicators. Based on the performance indicators, we could provide a practical guide to adsorbent selection and development for green H2 separation, where the 10 best COFs both for H2 raffinate and N2 raffinate cases were suggested.
Moreover, as a part of the multi-scale screening approach, we also propose a computation strategy that reduces the computational cost significantly in GCMC simulations. Based on the initial GCMC simulation results, the computation strategy determines the minimum number of GCMC simulations for adsorbent evaluation. By decreasing the number of simulations to the minimum numbers, the computation strategy could reduce at least 15 % of computational cost for our COF screening cases. For the finally selected COFs based on the performance indicators, the maximum value of normalized root mean square error (NRMSE) of all those adsorbents was smaller than 2.73 %, which barely deteriorates the entire adsorbent evaluation accuracy.
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