The I-point method for estimating the surface area of solid catalysts and the variation of C-term of the BET equation
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Pomonis, P. J.
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Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
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Pomonis, P. J.
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The BET equation rearranged in the form [V(1 - P)]/P = CVm - (C - 1)[V(1 - P)] was used for the calculation of specific surface areas of porous catalysts and the variation of C-term during the progress of adsorption. This novel method employs plots of [ V(1 - P)]/P vs. [V(1 - P)] which provide inclined-V type lines with an inversion point termed I-point. This I-point corresponds exactly to V(1 - P) = V-m, i.e., the volume of nitrogen necessary for the formation of a monolayer. The slope of the plots corresponds to (C - 1) from which the values of C can be estimated in the whole range 0 < P < 1. As the I-point is approached, the C values approach the C-BET values calculated from the classical linear BET plots. The free energy of adsorption in the whole range 0 < P < 1 can be also estimated from the relationship RTln C. (C) 2004 Elsevier B.V. All rights reserved.
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