Kinetic Rate Equations and Assumptions

To facilitate the development of the kinetic parameters for the HKR of epichlorohydrin, the global mechanism scheme (Fig. 12) has been simplified by only considering the three main reactions the hydrolysis of (S)-epichlorohydrin (rs) and (R)-epichlorohydrin (rR), and side-product formation [rf) (Eqs. 6-8). Assuming that HC1 transfer is fast, the formation of impurities can be considered as a single reaction. The result is the apparent reaction between epichlorohydrin and CPD to form glycidol and DCP. 

As mentioned in Section 2.3.2, glycidol and DCP are produced only in small amounts during the HKR reaction. Upon completion of the HKR, the equilibrium equations for DCP and glycidol formation are far from equilibrium and a non-equilibrated condition is assumed. Based upon these assumptions, the macroscopic kinetic law governing each reaction is expressed as a typical polynomial equation (Eqs. 9-11). 

For homogeneous systems, the kinetic parameters k and tq are commonly determined by lab-scale batch experiments in which all reagents are combined at the start of the reaction. Following the concentration of all components (reactants and products) over the course of the reaction then allows for the estimation of the kinetic parameters. Since water has limited solubility in the reaction mixture at the start, conventional kinetic batch experiments could result in erroneous calculation of kj and tq if the limits for homogeneity are crossed. To ensure reaction homogeneity and reliable kinetic measurements, the gradual and continuous addition of water was selected as a suitable method for experimentation (semi-batch mode). The kinetic parameters were then recovered using an appropriate mathematical model with parameter estimation module. 

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