The steep stepwise uptake of water vapor and easy release at low relative pressures and moderate temperatures together with high working capacities make metal−organic frameworks (MOFs) attractive, promising materials for energy efficient applications in adsorption devices for humidity control (evaporation and condensation processes) and heat reallocation (heating and cooling) by utilizing water as benign sorptive and low-grade renewable or waste heat. Emerging MOF-based process applications covered are desiccation, heat pumps/chillers, water harvesting, air conditioning, and desalination. Governing parameters of the intrinsic sorption properties and stability under humid conditions and cyclic operation are identified. Transport of mass and heat in MOF structures, at least as important, is still an underexposed topic. Essential engineering elements of operation and implementation are presented. An update on stability of MOFs in water vapor and liquid systems is provided, and a suite of 18 MOFs are identified for selective use in heat pumps and chillers, while several can be used for air conditioning, water harvesting, and desalination. Most applications with MOFs are still in an exploratory state. An outlook is given for further R&D to realize these applications, providing essential kinetic parameters, performing smart engineering in the design of systems, and conceptual process designs to benchmark them against existing technologies. A concerted effort bridging chemistry, materials science, and engineering is required.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We acknowledge valuable input and discussions with Prof. J.-S.Chang (KRICT), Dr. S. Marx (BASF), Dr. S.J. Ernst (ISE Fraunhofer), Prof. S. Wang (USTC), and Prof. M. Eddaoudi (KAUST). X.L. is grateful to the Peiyang Scholars Program (Tianjin University) for the New Professors Starting Grant. X.W. acknowledges the financial supports from the National Natural Science Foundation of China (21908097) and the Jiangsu Specially-Appointed Professors Program.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.