Pore System Characterizations

The characterization of the pore system is most crucial for most applications of porous media. But it is not only the size that matters, like for the application of zeolites as molecular sieves in membranes for the separation of gases, as shape-selective catalysts or for materials in size-exclusion chromatography. Additionally to the values of pore size and pore size distribution, the pore volume and the kinetics of the pore filling play an even more important role in most applications. For example in heterogeneous catalysis or in HPLC, these characteristics of the pore system are important factors for the mass transfer to the surface, where the desired interaction takes place.

We assist our customers by choosing an appropriate characterization method for their specific application - and for the kind of functional material they use. As a matter of fact, all values based on physico-chemical methods are valid only for the conditions under which they have been measured. Therefore we choose methods with maximum relevance and validity for your desired field of application. We have access to different methods, which can be performed under various conditions either in contact with gas phase or liquid phase - enabling even the characterization of the pore system of porous polymers in the swollen state by employing ISEC.

Furthermore, pore system characterizations may be employed for the investigation of defects in nonporous materials: cracks and fissures (even in the nm-range) are simple slit-pores in the eyes of pore-system specialists. Therefore our methods can eventually be employed to gather information at which stage during a production process problems occur and if and which activities help to prevent them - simply by checking bulk media.

The following examples represent the most often employed methods for specific tasks in pore system characterizations:

• gas sorption methods
  medium pore diameter • pore size distribution• pore volume - according to
  BJH • NLDFT-Method • Monte-Carlo-simulation • micropore volume via t-
  plot • kinetics of pore filling (hysteresis give indications of hindered pore
  filling or pore emptying processes)
  

• mercury intrusion
  medium pore diameter • pore size distribution • pore volume • interparticle
  volume • kinetics of pore filling (indications for bottleneck pores)
  

• inverse size exclusion chromatography (ISEC)
  medium pore diameter • pore size distribution • pore volume • influence of
  swelling in different solvents
  

• transmission electron microscopy (TEM)
  visual analysis of thin cuts
  

• X-ray diffraction (XRD)
  pore size
  

• temperature programmed desorption (TPD)
  pore volume • kinetics of pore filling
  

• pulse sorption
  pore volume • kinetics of pore filling
  

• chromatography related methods
  frontal analysis / breakthrough-curves • H-vs-u-curves ...
  

• helium-pyknometry
  determination of envelope density
  

Please contact us to check which method fits best for your needs.