Dr. Matthias Thommes Dr Matthias Thommes Quantachrome Instruments Boynton Beach, FL, USA      Surface Area Surface Area Pore Size/Volume Distribution P Pore Geometry, Structure of Pore Network G S fP N k Surface Properties Particle Size Distribution     Physical Adsorption Liquid Intrusion/Mercury Porosimetry Liquid Intrusion/Mercury Porosimetry Thermoporometry (by DSC, and NMR based techniques) Scattering Techniques (x Scattering Techniques (x‐ray ray and neutron scattering techniques such as and neutron scattering techniques such as SAXS, SANS, XRD)   Microscopy, (e.g.SEM, TEM) Combining gas adsorption with mercury porosimetry allows to assess a pore size range from ca. 0.3 nm up to 400 m! Micropores (pore size < 2 nm):  Micropore filling (continuous process) at very low relative pressures P/P0 < 0.15 0 15 Type I isotherm (IUPAC Classification) Mesopores (pore size 2 - 50 nm):  Multilayer adsorption, pore condensation and hysteresis (p pore condensation reflects as 1st order p phase transition,, i.e.,, discontinuous process) in relative pressure (P/P0) range from 0.15 – 1 T IV d V iisotherm h (IUPAC Classification) Cl ifi i ) Type IV, and Macroscopic thermodynamic methods Macroscopic, thermodynamic methods Micropores (< 2 mn): e.g., Dubinin‐Radushkevitch , Horvath‐Kawazoe (HK), Saito‐Foley Saito Foley (SF) , comparison plot methods (t (SF) , comparison plot methods (t‐method, method, alpha‐s method) Meso/Macropores (2‐100 nm): e.g., Kelvin equation based methods such as BJH (Barrett,Joyner, Halenda), or BDB (Brockhoff & de Boer) ( l d ) ( kh ff & d ) Modern, microscopic methods, based on statistical mechanics describe configuration of adsorbed molecules on a molecular describe configuration of adsorbed molecules on a molecular level : e.g., Density Functional Theory (DFT), Molecular Simulation these methods are applicable for pore size analysis of both the micro‐and mesopore size range.  An accurate pore size analysis over the complete pore size range can be performed by a single method. Calculation of the DFT Pore Size distribution ? Typical Pressure Ranges for Gas Sorption Calculation Methods p P/P0 Range Calculation Model Calculation Model • 10‐7 – 10‐7 – 1 1 • NLDFT, QSDFT, GCMC NLDFT QSDFT GCMC • 0.0001 – 0.1 • DR, DA (for Carbons) • < 0.15 0 15 • HK, SF HK SF • 0.05 – 0.3 (Classical BET range) • BET‐ for micropores apply procedure by Rouquerol et al. d b l l • > 0.15 • Comparison plot method:e.g, t‐plot, alpha‐s, FHH, • > 0.35 • BJH, DH, Fractal –FHH, NK