Rapid estimation of chemical kinetics by implicit calibration. I

In this study, methods for estimating kinetic parameters from on-line measurements of batch reactions are developed. The basic idea is to combine non-linear parameter estimation with implicit calibration between measured spectra and concentrations given by a known kinetic model. Several alternatives for the calibration step are discussed and the three most promising methods have been studied more closely. The basic ideas and identifiability questions are elucidated by simulation studies with simple kinetic models. The simulations show that the implicit calibration method works also with uncalibrated chromatograms. Two real esterification reactions with spectroscopic data are studied. In the first one, concentration data are available and our method gives results quite similar to those obtained in more traditional ways. The latter reaction, however, was a fast one and consequently off-line calibration based on known mixtures failed. In contrast, our method gave almost identical parameter values to the ones obtained by an independent study on the same reaction based on a complicated on-line chromatographic measurement system. In this case the results were compared with a new way of using pure component spectra and generalized ridge regression with stoichiometric constraints. Our studies show that the most important factors in obtaining reliable results are proper design of the batch experiments, proper weighting of the initial measurements of each batch and proper measure for goodness of fit. Copyright (C) 2001 John Wiley & Sons, Ltd.