THE EFFECT OF INTRAPARTICLE CONVECTION ON CONVERSION IN HETEROGENEOUSISOTHERMAL FIXED-BED REACTORS WITH LARGE-PORE CATALYSTS FOR FIRST-ORDER REACTIONS

Residence time distributions have been largely used in chemical engine ering to make diagnosis of the ill-functioning of chemical reactors an d to predict conversion in homogeneous isothermal reactors once the ki netic rate of reaction is known. The prediction is unambiguous for fir st-order reactions. In this paper, the impulse tracer response of isot hermal heterogeneous fixed-bed reactors packed with large-pore catalys ts, in which intraparticle convection occurs, is derived. From the imp ulse tracer response, the residence time distribution of the outer pha se is calculated and used to predict the steady state conversion in th e reactor for first-order reactions. The effect of intraparticle conve ction, measured by the intraparticle Peclet number lambda for a given reaction-catalyst system, i.e. for a set of Damkholer, Thiele, Biot an d Peclet numbers (Da, phi, Bi-m and Pe respectively) is to drive the c onversion between the diffusion-controlled and the kinetic-controlled limits. The problem of scaling from batch to continuous packed beds is also addressed.