Calibration-Free Estimates of Batch Process Yields and Detection of Process Upsets Using in Situ Spectroscopic Measurements and Nonisothermal Kinetic Models:  4-(Dimethylamino)pyridine- Catalyzed Esterification of Butanol

Abstract

In this paper, we report the use of an NIR fiber-optic spectrometer with a high-speed diode array for calibration-free monitoring and modeling of the reaction of acetic anhydride with butanol using the catalyst 4-(dimethylamino)pyridine in a microscale batch reactor. Acquisition of spectra at 5 ms/scan gave information relevant for modeling these fast batch processes with a single multibatch kinetic model. Nonlinear fitting of a first-principles model directly to the reaction spectra gave calibration-free estimates of time-dependent concentration profiles and pure component spectra. The amount of catalyst was varied between different batches to permit accurate estimation of its effect in the multiway model. A wide range of different models with increasing complexity could be fit to each batch individually with low residuals and apparent low lack of fit. However, only one model properly estimated the concentration profiles when all five batches were fitted simultaneously in a multiway kinetic model. Inclusion of on-line temperature measurements and use of an Arrhenius model for the estimated rate constant gave significantly improved model fits compared to an isothermal kinetic model. Augmentation of prerun batches with data from an additional batch permitted model-based forecasts of reaction trajectories, reaction yield, reaction end points, and process upsets. One batch with added water to simulate a process upset was easily detected by the calibration free process model.

Focus on the potential of hybrid hard‐ and soft‐MCR–ALS in time resolved spectroscopy

“…Data sets R 1 and R 2 consist of two repetitions at low and high flash excitation levels of rapid scan FTIR experiments, in the range of 1784-1243 cm À1 , monitoring a photochemical process described in [18,19]. Each data matrix contains 21 difference spectra recorded at 187 wavelengths.…”

“…, monitoring a photochemical process described in [18,19]. Each data matrix contains 21 difference spectra recorded at 187 wavelengths.…”

Principle component analysis (PCA) and second-order global hard-modelling for the complete resolution of transition metal ions complex formation with 1,10-phenantroline

“…Temperature [3,11] and pH changes [12] during the process, are modelled. Initially, applications have been restricted to academic investigations but recently they have started to exploit these capabilities for the investigation of industrially relevant processes [13].…”

Uncertainties and error propagation in kinetic hard-modelling of spectroscopic data

“…The method used in this work, kinetic hard-modelling, does allow for both interpolation and extrapolation when an appropriate empirical or molecular rate law is applied reflecting the underlying reaction mechanism [14][15][16][17][18][19]. This task is facilitated by the recent development of multivariate analytical in-situ devices and optimisation algorithms [20,21].…”