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Immersion Calorimetry: Molecular Packing Effects in Micropores
Author(s) -
Madani S. Hadi,
SilvestreAlbero Ana,
Biggs Mark J.,
RodríguezReinoso Francisco,
Pendleton Phillip
Publication year - 2015
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201500580
Subject(s) - microporous material , adsorption , calorimetry , enthalpy , differential scanning calorimetry , chemistry , analytical chemistry (journal) , immersion (mathematics) , dichloromethane , nitrogen , furfuryl alcohol , materials science , chemical engineering , chromatography , organic chemistry , thermodynamics , physics , mathematics , solvent , pure mathematics , engineering , catalysis
Repeated and controlled immersion calorimetry experiments were performed to determine the specific surface area and pore‐size distribution (PSD) of a well‐characterized, microporous poly(furfuryl alcohol)‐based activated carbon. The PSD derived from nitrogen gas adsorption indicated a narrow distribution centered at 0.57±0.05 nm. Immersion into liquids of increasing molecular sizes ranging from 0.33 nm (dichloromethane) to 0.70 nm (α‐pinene) showed a decreasing enthalpy of immersion at a critical probe size (0.43–0.48 nm), followed by an increase at 0.48–0.56 nm, and a second decrease at 0.56–0.60 nm. This maximum has not been reported previously. After consideration of possible reasons for this new observation, it is concluded that the effect arises from molecular packing inside the micropores, interpreted in terms of 2D packing. The immersion enthalpy PSD was consistent with that from quenched solid density functional theory (QSDFT) analysis of the nitrogen adsorption isotherm.