Nanoporous materials include activated carbons, zeolites, aluminas, mesoporous silicas, and metal-organic frameworks. They can be characterized using adsorption but they also find widespread use as adsorbents in industrial applications.
Surface area, pore volume, and pore size distribution can all be determined by analyzing N2 adsorption data. In addition, depending on the material, Ar and CO2 adsorption can provide important complementary information.
When adsorbents are used for separating gases, their adsorption behavior as a function of temperature and pressure must also be characterized, to obtain working capacities, selectivities, and enthalpies of adsorption.
Metal-organic frameworks (MOFs) are crystalline inorganic-organic solids formed from metal ions or clusters linked by organic bridges. They have been widely investigated in recent years for gas and vapor adsorption applications due to their unique porous properties and tunable structures.
Determining the gas adsorption properties of MOFs is important for application-oriented research, but also for characterizing newly synthesized materials.
Zeolites are crystalline microporous aluminosilicates. They have a range of applications that exploit their ion exchange, molecular sieving and catalytic properties. Gas and vapor adsorption plays a critical role in many of their practical applications, but it can also be used to characterize the properties of new zeolitic materials.
Industrial applications involving the gas and vapor sorption properties of synthetic zeolites include hydrogen, helium and natural gas purification using pressure swing adsorption (PSA), oxygen production from air using PSA, and the separation of hydrocarbons, such as olefins from paraffins, n-paraffins from iso-paraffins and cyclic paraffins from aromatics.
Zeolites are also widely used in heterogeneous catalysis. Adsorption is a fundamental step in such catalytic reactions, while the diffusion (mass transport) rates of both the reactants and products play a key role in the catalytic performance of a particular material.
- Pore size distribution determination
- Surface area determination (e.g. BET analysis)
- Mass transport and uptake kinetics
- Adsorption thermodynamics
Hiden Isochema instruments have been used extensively to study the adsorption properties of zeolites, MOFs, and other nanoporous materials. The IGA-001 gravimetric analyzer can determine single component gas adsorption, while the IGA-002 can be used for vapor sorption and the IGA-003 and IGA-100 offer gas and vapor mixture capability. The IMI-FLOW can be used for flowing gas mixture measurements with a close-coupled quadrupole mass spectrometer from Hiden Analytical.
High Accuracy Gravimetric Analyzer, for Precise Characterization of Gas Sorption Equilibria and Kinetics
Single Component Gravimetric Analyzer, for Precise Characterization of Gas and Vapor Sorption Equilibria and Kinetics
Manometric hydrogen sorption analyzer, for investigation of novel storage materials