Statistical rate theory of interfacial transport. III. Predicted rate of nondissociative adsorption

Abstract

The statistical rate theory approach is used to derive the expression for the rate of adsorption of a nondissociating gas on a solid surface. By comparing the predicted adsorption with the available experimental results, one of the central assumptions in the statistical rate theory can be examined. On the basis of these experimental results, with which the theoretical predictions are found to be in close agreement, the assumption would appear to be valid. By being in close agreement with the experimental results throughout the experimental period, the adsorption rate expression derived from the statistical rate theory is an improvement over the presently available theories.

Statistical rate theory description of beam-dosing adsorption kinetics

“…If the solid is large enough that the adsorption takes place isothermally, SRT may be used to formulate the expression for the instantaneous rate of adsorption, J. In this case, one finds 7,12,14,15 …”

“…Previously, the equilibrium adsorption cross section was taken to be the cross sectional area of a site multiplied by a probability. 12,14,15 We suppose it to be simply the geometrical area of an adsorption site…”

“…2,4 Statistical rate theory is being developed with the objective of filling this need. [5][6][7][8][9][10][11][12][13][14][15][16] In this approach, a thermodynamically isolated system is considered and the transition probability concept is used to construct the expression for the rate of molecular transport. If this approach is successful, the material properties of a particular pair of macroscopic phases could be tabulated and used in the governing equations for predicting the rate of molecular transport across the interface in any circumstance.…”

“…The SRT approach shows promise of being successful, but it has not been fully tested previously. Since it was first proposed in an elementary form in 1977, 5 it has been placed on firmer theoretical grounds 6,7 and applied to examine the rates of gas absorption at a liquid-gas interface, [8][9][10] hydrogen absorption by metals, 11 electron exchange between ionic isotopes in solution, 6,12 permeation of ionic channels in biological membranes, 13 and both nondissociative 12,14,15 and dissociative 14,16 adsorption kinetics in isothermal, isobaric systems. In each case, the SRT approach led to improvements in the theoretical description of the rate process.…”

“…The exception is the ''adsorption cross section'' that has been previously defined. 12,14,15 In an isolated system, SRT leads to the prea͒ Present address: Department of Chemistry and Materials Engineering, Univ. Alberta, Edmonton, Canada T6G 26G.…”