Sorbent materials are candidates for many industrial and sustainable development applications, including carbon capture and sequestration, hydrogen and methane storage, gas separation and purification, and catalysis. However, reliable and reproducible sorption measurements are challenging to obtain due to variations in sample preparation and/or measurement protocols.
The NIST Facility for Adsorbent Characterization and Testing (FACT Lab) is a 7500 sq. ft. state-of-the-art laboratory, located at the Gaithersburg campus of the National Institute of Standards and Technology (NIST). The FACT Lab addresses challenges associated with measuring gas and vapor sorption. The lab is equipped with a range of instruments, including manometric measurements of adsorption, gravimetric measurements of adsorption, measurements of mixed-gas adsorption, and the measurement of related physicochemical properties of porous materials. A unique feature of the lab is the capability to make high-pressure measurements, to 10 MPa. The FACT Lab seeks to improve the adsorption sciences through a better understanding of adsorption technologies, generating reference data related to adsorption and the properties of adsorbates using reference materials, and in turn using these capabilities to perform scientific studies of novel, porous materials.
Research activities include understanding and optimizing adsorption instrumentation and developing protocols for obtaining reproducible and accurate measures of adsorption-related quantities, ranging from adsorption fundamentals to specific adsorption applications. For example, while manometric, gravimetric, and characterization instruments have existed for some time, obtaining measurements with percent-level uncertainties, such as the equilibrium loading, has proved elusive. Previous FACT Lab studies include assessing the effects of activation on the measurement of skeletal density, clarifying the optimal methods for implementing the buoyancy correction in gravimetric measurements, and perfecting methods for calibrating total volume and partitioned volume in manometric measurements.
The FACT Lab also generates reference adsorption isotherms using reference materials. This has included carbon dioxide (CO2) on ZSM-5 (NIST Reference Material 8852) and methane (CH4) on Zeolite Y (NIST Reference Material 8850). Both materials are nanoporous, aluminosilicate materials, with carefully characterized physicochemical properties. Another example is the adsorption of water on nanoporous carbon (BAM Reference Material P109) for relative humidity to 95%. All these materials are available to the public for purposes of evaluating and benchmarking adsorption instrument performance and comparison to the properties of other nanoporous materials.
Finally, using these capabilities, the FACT Lab performs studies to investigate the fundamental adsorption properties and adsorption mechanisms of novel porous substances in collaboration with materials discovery scientists. Examples include water vapor adsorption on mesoporous silica (e.g. SBA-15), water and ethanol vapor adsorption on hierarchical all-silica zeolites, and binary gas adsorption of metal-organic-frameworks (e.g. MIL-53)
Current interests of the FACT Lab include exploring quantitative measurement of adsorption of binary gas mixtures on reference materials, further exploration of instrument performance, and generation of reference isotherms.
More about the FACT Lab along with references for the works cited above can be found at the web-site, adsorption.nist.gov.
Adsorbents; Carbon capture materials; Catalysis; Gas purification; Gas separations; Hydrogen and methane storage; Membranes; Porous materials; Zeolites