Simultaneous determination of intraparticle diffusivities from ternary component uptake curves using the shallow bed technique

In order to design and operate a fixed-bed reactor, accurate modeling is important. For a single component system, the determination of intraparticle diffusivity is rather easy. However, the calculations of multi-component systems are normally complicated and very time-consuming. Therefore, an alternative simple determination procedure using the shallow bed technique is proposed in this research to determine the intraparticle diffusivities for multi-component systems. Ternary component systems of phenol (PH), benzoic acid (BA), and p-nitro-phenol (PNP) were investigated as model components. This study illustrated that adsorption uptake curves of different components in ternary systems can be converted into one typical characteristic curve (theoretical uptake curve, TUC) by using a set of dimensionless groups. By matching the dimensionless experimental uptake curve (DEUC) with TUC, diffusivities of PH, BA and PNP were determined as 8.00 × 10−8, 5.92 × 10−8 and 5.05 × 10−8 cm2 s−1, respectively. These values are in good agreement with simulated experimental values. This study demonstrated that the shallow bed technique can be used to simultaneous determination of intraparticle diffusivities from multi-component systems.