Multicomponent reaction and diffusion in a tubular reactor: an operator-theoretic solution

Mathematical models describing isothermal tubular reactors in which first-order chemical reactions and uncoupled multicomponent diffusion occur are solved by a linear operator formalism. A pseudohomogeneous axial dispersion model accounting for both bulk-fluid-phase dispersion and intraparticle diffusion is solved to examine the effect of widely disparate configuration diffusion coefficients on selectivity in the reactor. The operator formalism is shown to obtain also solutions for the mathematically more complicated situation of a wall-catalyzed reactor with a nonuniform, fully developed flow profile. Computations presented for the axial dispersion model demonstrate that intraparticle diffusion hindrances in molecular sieve catalysts can drastically affect the selectivity of the xylene isomerization system. The influence of reactor parameters (Peclet and Damkohler numbers) and reactor feed conditions on product selectivity is investigated in order to elucidate the conditions under which optimum selectivity can be expected.