Evaluation of energy distribution on a heterogeneous surface from heat of adsorption and its application to the ammonia/Na-Y zeolite system

Abstract

Theε—θ function (energy level function) which represents surface heterogeneity was derived from theq—θ function (experimental heat function) in the case of reversible adsorption. The Langmuir equation was extended and applied to the procedure of calculations. An iterative calculation led to the most probableε—θ function by setting theq—θ function and adsorption temperature. As an example for actual cases, theε—θ function of Na-Y zeolite was calculated from theq—θ function obtained by the measurement of heats of adsorption of ammonia at 373 K. Theε—θ function thus derived seemed to be consistent with the positional distribution of sodium ions.