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Siderius DW, Hatch HW, Shen VK. Flat-Histogram Monte Carlo Simulation of Water Adsorption in Metal-Organic Frameworks. J Phys Chem B 2024; 128:4830-4845. [PMID: 38676704 PMCID: PMC11175621 DOI: 10.1021/acs.jpcb.4c00753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2024]
Abstract
Molecular simulations of water adsorption in porous materials often converge slowly due to sampling bottlenecks that follow from hydrogen bonding and, in many cases, the formation of water clusters. These effects may be exacerbated in metal-organic framework (MOF) adsorbents, due to the presence of pore spaces (cages) that promote the formation of discrete-size clusters and hydrophobic effects (if present), among other reasons. In Grand Canonical Monte Carlo (MC) simulations, these sampling challenges are typically manifested by low MC acceptance ratios, a tendency for the simulation to become stuck in a particular loading state (i.e., macrostates), and the persistence of specific clusters for long periods of the simulation. We present simulation strategies to address these sampling challenges, by applying flat-histogram MC (FHMC) methods and specialized MC move types to simulations of water adsorption. FHMC, in both Transition-matrix and Wang-Landau forms, drives the simulation to sample relevant macrostates by incorporating weights that are self-consistently adjusted throughout the simulation and generate the macrostate probability distribution (MPD). Specialized MC moves, based on aggregation-volume bias and configurational bias methods, separately address low acceptance ratios for basic MC trial moves and specifically target water molecules in clusters; in turn, the specialized MC moves improve the efficiency of generating new configurations which is ultimately reflected in improved statistics collected by FHMC. The combined strategies are applied to study the adsorption of water in CuBTC and ZIF-8 at 300 K, through examination of the MPD and the adsorption isotherm generated by histogram reweighting. A key result is the appearance of nontrivial oscillations in the MPD, which we show to be associated with water clusters in the adsorption system. Additionally, we show that the probabilities of certain clusters become similar in value near the boundaries of the isotherm hysteresis loop, indicating a strong connection between cluster formation/destruction and the thermodynamic limits of stability. For a hydrophobic MOF, the FHMC results show that the phase transition from low density to high density is suppressed to water pressure far above the bulk-fluid saturation pressure; this is consistent with results presented elsewhere. We also compare our FHMC simulation isotherm to one measured by a different technique but with ostensibly the same molecular interactions and comment on observed differences and the need for follow-up work. The simulation strategies presented here can be applied to the simulation of water in other MOFs using heuristic guidelines laid out in our text, which should facilitate the more consistent and efficient simulation of water adsorption in porous materials in future applications.
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Affiliation(s)
- Daniel W. Siderius
- Chemical Sciences Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8320, United States
| | - Harold W. Hatch
- Chemical Sciences Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8320, United States
| | - Vincent K. Shen
- Chemical Sciences Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8320, United States
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Wang X, Alzayer M, Shih AJ, Bose S, Xie H, Vornholt SM, Malliakas CD, Alhashem H, Joodaki F, Marzouk S, Xiong G, Del Campo M, Le Magueres P, Formalik F, Sengupta D, Idrees KB, Ma K, Chen Y, Kirlikovali KO, Islamoglu T, Chapman KW, Snurr RQ, Farha OK. Tailoring Hydrophobicity and Pore Environment in Physisorbents for Improved Carbon Dioxide Capture under High Humidity. J Am Chem Soc 2024; 146:3943-3954. [PMID: 38295342 DOI: 10.1021/jacs.3c11671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2024]
Abstract
CALF-20, a Zn-triazolate-based metal-organic framework (MOF), is one of the most promising adsorbent materials for CO2 capture. However, competitive adsorption of water severely limits its performance when the relative humidity (RH) exceeds 40%, limiting the potential implementation of CALF-20 in practical settings where CO2 is saturated with moisture, such as postcombustion flue gas. In this work, three newly designed MOFs related to CALF-20, denoted as NU-220, CALF-20M-w, and CALF-20M-e that feature hydrophobic methyltriazolate linkers, are presented. Inclusion of methyl groups in the linker is proposed as a strategy to improve the uptake of CO2 in the presence of water. Notably, both CALF-20M-w and CALF-20M-e retain over 20% of their initial CO2 capture efficiency at 70% RH─a threshold at which CALF-20 shows negligible CO2 uptake. Grand canonical Monte Carlo simulations reveal that the methyl group hinders water network formation in the pores of CALF-20M-w and CALF-20M-e and enhances their CO2 selectivity over N2 in the presence of a high moisture content. Moreover, calculated radial distribution functions indicate that introducing the methyl group into the triazolate linker increases the distance between water molecules and Zn coordination bonds, offering insights into the origin of the enhanced moisture stability observed for CALF-20M-w and CALF-20M-e relative to CALF-20. Overall, this straightforward design strategy has afforded more robust sorbents that can potentially meet the challenge of effectively capturing CO2 in practical industrial applications.
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Affiliation(s)
- Xiaoliang Wang
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Maytham Alzayer
- Department of Chemical & Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Arthur J Shih
- Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Saptasree Bose
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Haomiao Xie
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Simon M Vornholt
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Christos D Malliakas
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Hussain Alhashem
- Department of Chemical & Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Faramarz Joodaki
- Department of Chemical & Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Sammer Marzouk
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Grace Xiong
- Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Mark Del Campo
- Rigaku Americas Corporation, The Woodlands, Texas 77381, United States
| | | | - Filip Formalik
- Department of Chemical & Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Department of Micro, Nano and Bioprocess Engineering, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland
| | - Debabrata Sengupta
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Karam B Idrees
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Kaikai Ma
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Yongwei Chen
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Kent O Kirlikovali
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Timur Islamoglu
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Karena W Chapman
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Randall Q Snurr
- Department of Chemical & Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Omar K Farha
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemical & Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
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Rajendran A, Subraveti SG, Pai KN, Prasad V, Li Z. How Can (or Why Should) Process Engineering Aid the Screening and Discovery of Solid Sorbents for CO 2 Capture? Acc Chem Res 2023; 56:2354-2365. [PMID: 37607397 DOI: 10.1021/acs.accounts.3c00335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
ConspectusAdsorption using solid sorbents is emerging as a serious contender to amine-based liquid absorption for postcombustion CO2 capture. In the last 20+ years, significant efforts have been invested in developing adsorption processes for CO2 capture. In particular, significant efforts have been invested in developing new adsorbents for this application. These efforts have led to the generation of hundreds of thousands of (hypothetical and real) adsorbents, e.g., zeolites and metal-organic frameworks (MOFs). Identifying the right adsorbent for CO2 capture remains a challenging task. Most studies are focused on identifying adsorbents based on certain adsorption metrics. Recent studies have demonstrated that the performance of an adsorbent is intimately linked to the process in which it is deployed. Any meaningful screening should thus consider the complexity of the process. However, simulation and optimization of adsorption processes are computationally intensive, as they constitute the simultaneous propagation of heat and mass transfer fronts; the process is cyclic, and there are no straightforward design tools, thereby making large-scale process-informed screening of sorbents prohibitive.This Account discusses four papers that develop computational methods to incorporate process-based evaluation for both bottom-up (chemistry to engineering) screening problems and top-down (engineering to chemistry) inverse problems. We discuss the development of the machine-assisted adsorption process learning and emulation (MAPLE) framework, a surrogate model based on deep artificial neural networks (ANNs) that can predict process-level performance by considering both process and material inputs. The framework, which has been experimentally validated, allows for reliable, process-informed screening of large adsorbent databases. We then discuss how process engineering tools can be used beyond adsorbent screening, i.e., to estimate the practically achievable performance and cost limits of pressure vacuum swing adsorption (PVSA) processes should the ideal bespoke adsorbent be made. These studies show what conditions stand-alone PVSA processes are attractive and when they should not be considered. Finally, recent developments in physics-informed neural networks (PINNS) enable the rapid solution of complex partial differential equations, providing tools to potentially identify optimal cycle configurations. Ultimately, we provide areas where further developments are required and emphasize the need for strong collaborations between chemists and chemical engineers to move rapidly from discovery to field trials, as we do not have much time to fulfill commitments to net-zero targets.
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Affiliation(s)
- Arvind Rajendran
- Donadeo Innovation Centre for Engineering, University of Alberta, 9211-116 Street NW, Edmonton, AB T6G 1H9, Canada
| | - Sai Gokul Subraveti
- Donadeo Innovation Centre for Engineering, University of Alberta, 9211-116 Street NW, Edmonton, AB T6G 1H9, Canada
- SINTEF Energy Research, Trondheim 7019, Norway
| | - Kasturi Nagesh Pai
- Donadeo Innovation Centre for Engineering, University of Alberta, 9211-116 Street NW, Edmonton, AB T6G 1H9, Canada
- Svante Structured Adsorbents Centre of Excellence, 3021 Underhill Ave, Burnaby, BC V5A 3C2, Canada
| | - Vinay Prasad
- Donadeo Innovation Centre for Engineering, University of Alberta, 9211-116 Street NW, Edmonton, AB T6G 1H9, Canada
| | - Zukui Li
- Donadeo Innovation Centre for Engineering, University of Alberta, 9211-116 Street NW, Edmonton, AB T6G 1H9, Canada
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