Some practical aspects of nonlinear frequency response method for investigation of adsorption equilibrium and kinetics

Some practical aspects regarding application of the nonlinear frequency response (NFR) method for investigation of gas adsorption: choice of the optimal mass of the adsorbent, frequency range and input amplitude, are studied theoretically. For successful application of the NFR method, reliable experimental determination of the second-order frequency response function (FRF) is essential. In order to analyse the influence of the mass of the adsorbent, the frequency range and the input amplitude on the accuracy of the estimated the second-order FRF, frequency responses (FRs) of a batch adsorber with volume modulation are simulated and used for calculation of the second-order FRF. Furthermore, the procedure for estimation of the optimal mass of the adsorbent, required frequency range and input amplitude, based on simple preliminary step responses, is proposed. In order to demonstrate the procedure, responses of the batch adsorber for the step volume change are also simulated. The proposed procedure enables establishment of the efficient experimental plan for application of the NFR method.

► Practical aspects of application of nonlinear frequency response method are studied.
► Step and frequency responses of a batch adsorber are simulated.
► Requirements for reliable determination of the second order FRF are acsertained.
► A procedure for design of the efficient experiments is proposed.
► Input amplitude of 8% is found to be suitable for NFR experiments.