Determination of transport coefficients in microporous solids

Mass Transfer in Micro- and Mesoporous Materials

“…Differences in molecular positions at two subsequent intervals, however, represent nothing other than their displacements. As an analytical expression of the attenuation of the NMR signal one obtains [6,9,27], Macroscopic Sorption/Desorption [10] Frequency Response (FR) [11] Zero Length Column (ZLC) [12] IR-FR [13] Positron Emission Prof. (PEP) [14] Temporal Product Analysis (TAP) [15] IR Spectroscopy [16] MembranePermeation [5] Effectiveness Factor during Catalytic Reaction [17] Tracer Sorption/Desorption [6] Tracer ZLC [12] Mesoscopic IR Microscopy [18] Single-Crystal Permeation [19] Tracer IR Microscopy [18] Microscopic Interference Microscopy [20] Pulsed Field Gradient NMR (PFG NMR) [1,6] Stray Field Gradient NMR (SFG NMR) [21] Quasi-Elastic Neutron-Scattering (QENS) [22] Exchange NMR [23] where d, g and t denote the width, amplitude and separation of the gradient pulses. The ªgyromagnetic ratioº c is a characteristic quantity of the given nucleus.…”

Comment on the paper “Diffusion and adsorption selectivities of hydrocarbons over FCC catalysts” by A.M. Ávila, C.M. Bidabehere and U. Sedran [Chem. Eng. J. 132 (2007) 67–75]

“…the absence of any notable surface resistance. Over many years, surface barriers were assumed to be among the main mechanisms giving rise to the discrepancy between microscopic and macroscopic diffusion measurements [29,30]. Today, in addition to these surface barriers, also internal resistances [31][32][33][34] have been identified as further sources of impedance of molecular propagation acting in addition to the drag exerted by the genuine pore system.…”

Adsorption and desorption kinetics of hydrocarbons in FCC catalysts studied using a tapered element oscillating microbalance (TEOM). Part 2: numerical simulations

“…by varying carrier gas owrate, varying adsorbate loading, and varying particle size) in order to obtain reliable information (K arger and Ruthven, 1992;B ulow and Micke, 1995;Brandani et al, 1996;Loos et al, 2000). Failure to do so may result in incorrect analysis, particularly if the wrong limiting mass transport step is identiÿed.…”