Modelling of Pervaporation Membrane Reactors

The first pervaporation membrane reactor model which takes into account solution non-idealities was developed and validated experimentally by Zhu et al [5.90]. Prior studies [5.89, 5.91] also made note of such non-idealities, but offered no unified means for accounting for these phenomena in the description of PVMR. Since the model of Zhu et al. [5.90] appeared, other groups have also utilized similar models [5.92]. A more comprehensive analog of this model was, for example, recently presented and validated experimentally by Park [5.93], and by Lim et al. [5.94]. Zhu et al. [5.90] analyzed a tubular PVMR, in which the homogeneously catalyzed esterification reaction of acetic acid with ethanol to produce ethyl acetate and water took place. The reaction can be expressed generally as  

For the calculation of the activity coefficients use is made of the UNIQUAC equation 

The following assumptions were made in developing the equations for the model for the plug-flow pervaporation membrane reactor (PFPVMR) The reactor behaves as an 

In the above Da is a modified Damkohler number (ratio of a characteristic flow time to a characteristic reaction time), Dw is the ratio of a characteristic time for flow to the characteristic time for transport, and Q is their ratio (the ratio of the characteristic time for reaction to that for transport). Equations 5.35 and 5.36 become dimensionless as  

Reactor conversion for the PFPVMR configuration as a function of the modified Damkohler number. Da, for various values of the parameter Q, is shown in Fig. 5.23. The line for Q=0 represents the conversion of a conventional plug-flow reactor (PFR). 

---