Quenched solid density functional theory and pore size analysis of micro-mesoporous carbons

• Published in: Carbon (New York) Vol. 47; no. 7; pp. 1617 - 1628
• Main Authors: Neimark, Alexander V., Lin, Yangzheng, Ravikovitch, Peter I., Thommes, Matthias
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-06-2009; Elsevier
• Subjects: Adsorbents; Chemistry; Colloidal state and disperse state; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; General and physical chemistry; Materials science; Physics; Porous materials; Specific materials; Surface physical chemistry; Water; Plane surface; Micropore; Porosimetry; Porous materials; Roughness; Artefact; Calculus; Silica; Adsorbents; Template; Pore size; Activated carbon; Distribution function; Argon; Purification; Nitrogen; Carbon; Mesoporosity; Functional theory; Carbon fibers; Microporosity; Density functional; Adsorption; Pore; Low pressure; Distribution; Graphite; Solids; Adsorption isotherms; Models
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2009.01.050

We present a new model of adsorption on micro-mesoporous carbons based on the quenched solid density functional theory (QSDFT). QSDFT quantitatively accounts for the surface geometrical inhomogeneity in terms of the roughness parameter. We developed the QSDFT models for pore size distribution calculations in the range of pore widths from 0.4 to 35 nm from nitrogen at 77.4
K and argon at 87.3
K adsorption isotherms. The QSDFT model improves significantly the method of adsorption porosimetry: the pore size distribution (PSD) functions do not possess gaps in the regions of ∼1
nm and ∼2
nm, which are typical artifacts of the standard non-local density functional theory (NLDFT) model that treats the pore walls as homogeneous graphite-like plane surfaces. The advantages of the QSDFT method are demonstrated on various carbons, including activated carbons fibers, coal based granular carbon, water purification adsorbents, and mirco-mesoporous carbon CMK-1 templated on MCM-48 silica. The results of PSD calculations from nitrogen and argon are consistent, however, argon adsorption provides a better resolution of micropore sizes at low vapor pressures than nitrogen adsorption.