Predictive multiple reaction monitoring

Bauer et al. describe the use of a noncontact probe coupled by fiber optics to an FT-Raman system to measure the percentage of dry extractibles and styrene monomer in a styrene/butadiene latex emulsion polymerization reaction using PLS models [201]. Elizalde et al. have examined the use of Raman spectroscopy to monitor the emulsion polymerization of n-butyl acrylate with methyl methacrylate under starved, or low monomer [202], and with high soUds-content [203] conditions. In both cases, models could be built to predict multiple properties, including solids content, residual monomer, and cumulative copolymer composition. Another study compared reaction calorimetry and Raman spectroscopy for monitoring n-butyl acrylate/methyl methacrylate and for vinyl acetate/butyl acrylate, under conditions of normal and instantaneous conversion [204], Both techniques performed well for normal conversion conditions and for overall conversion estimate, but Raman spectroscopy was better at estimating free monomer concentration and instantaneous conversion rate. However, the authors also point out that in certain situations, alternative techniques such as calorimetry can be cheaper, faster, and often easier to maintain accurate models for than Raman spectroscopy, hi a subsequent article, Elizalde et al. found that updating calibration models after... 

Sequential application of the steady-state design equations is required when multiple chemical reactions occur in a series configuration of well-mixed tanks. If temperature, residence time, kinetic rate laws, and the characteristics of the feed to the first reactor are known, then it is possible to predict molar densities in the exit stream of the first reactor, which represent the feed to the second reactor, and so on. Subscripts are required to monitor ... 

Accepting these limitations mid-IR is a powerM tool. It is capable of monitoring reaction kinetics, appearance and disappearance of intermediates, prediction end point, and even in some cases the presence of PRIs. Figure 9.11 shows the type of data that can be generated and the way mid-IR can be used to track multiple changes as they occur with a reaction step. 

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