Mathematical modeling of dehydration of THF+water in a fixed bed column

The adsorption of tetrahydrofuran (THF) + water mixture on zeolite molecular sieves was carried out using a fixed-bed column. A pore diffusion model (PDM) was proposed to predict the adsorption breakthrough curves in a fixed bed with respect to initial concentrations and feed flow rates. The equilibrium behavior was shown to fit a Langmuir isotherm. A mathematical modeling for the adsorption process is developed and illustrated for THF- water mixture. The model deals with the effect of axial dispersion and inter- and intraparticle mass-transfer resistances at isothermal operating conditions. Four types of molecular sieves (3A, 4A, 5A, and 13X) were used. Orthogonal collocation was used to solvethe coupled non-linear parabolic partial differential equations for simultaneous adsorption, which include the effects of axial diffusion in the fluid, the film resistance, and internal diffusional resistance of particles. Felberg’s Runge-Kutta methods were used to solve the dimensionless 4N-coupled ordinary differential equations. Moreover, the influences of the bed Reynolds number, Peclet number, and the diameter of the spherical molecular sieves on the breakthrough curve were investigated.

Keywords:

Molecular sieves , Adsorption , Isotherms , Pore Diffusion model , Orthogonal Collocation