1 research outputs found
Advanced Structural Analysis of Nanoporous Materials by Thermal Response Measurements
Thermal response measurements based
on optical adsorption calorimetry
are presented as a versatile tool for the time-saving and profound
characterization of the pore structure of porous carbon-based materials.
This technique measures the time-resolved temperature change of an
adsorbent during adsorption of a test gas. Six carbide and carbon
materials with well-defined nanopore architecture including micro-
and/or mesopores are characterized by thermal response measurements
based on <i>n</i>-butane and carbon dioxide as the test
gases. With this tool, the pore systems of the model materials can
be clearly distinguished and accurately analyzed. The obtained calorimetric
data are correlated with the adsorption/desorption isotherms of the
materials. The pore structures can be estimated from a single experiment
due to different adsorption enthalpies/temperature increases in micro-
and mesopores. Adsorption/desorption cycling of <i>n</i>-butane at 298 K/1 bar with increasing desorption time allows to
determine the pore structure of the materials in more detail due to
different equilibration times. Adsorption of the organic test gas
at selected relative pressures reveals specific contributions of particular
pore systems to the increase of the temperature of the samples and
different adsorption mechanisms. The use of carbon dioxide as the
test gas at 298 K/1 bar provides detailed insights into the ultramicropore
structure of the materials because under these conditions the adsorption
of this test gas is very sensitive to the presence of pores smaller
than 0.7 nm