NONLINEAR SORPTION ISOTHERM OF ZEOLITES BY FREQUENCY-RESPONSE ANALYSIS

Frequency response analysis was used to study the physical adsorption and diffusion of ethene on 13X molecular sieves, a system for which th e adsorption isotherm has a relatively large curvature. Transient expe riments were carried out in a Berty reactor with effluent sample analy sis every 0.5 s. Mathematical models describing sorption-diffusion wer e solved by applying perturbation theory and Laplace transform. Fast F ourier transform was used to separate the responses into the fundament al and first harmonic frequencies. The slope and curvature of the sorp tion isotherm and effective diffusivity were determined by applying th e Hooke and Jeeves algorithm. The sorption isotherm constructed with d ata from dynamic experiments was comparable to the isotherm from stead y-state experiments.