DISPERSION EFFECTS ON MEMBRANE REACTOR PERFORMANCE

A mathematical model has been developed that predicts the effects of d esign parameters, operating variables and physical properties on the p erformance of a membrane reactor with a permselective wall. The model consists of the full set of partial differential equations that descri be the conservation of mass, momentum and chemical species, coupled wi th chemical kinetics and appropriate boundary conditions for the physi cal problem. The solution of this system is obtained by a finite-volum e technique. The model was applied to study the dehydrogenation of cyc lohexane. Two membrane types in tubular form were studied: a selective porous glass with low gas permeabilities and a porous alumina with ve ry high gas permeabilities. It is concluded that gas separation and re actor performance are strongly influenced by dispersion effects only i n the latter membrane reactor, while in both cases radial concentratio n profiles do not correspond to those obtained with plug flow. Therefo re, simulations of this type of problem should be based on complex dis persion models rather than the existing ideal plug-flow ones.