Catalyst particle modelling in fixed-bed reactors

The steady-state operation of a fixed-bed reactor is described by a detailed computational model which includes simulation of heat and mass transport in the catalyst particles and their boundary layers. Intraparticle mass transport is described by an extended dusty gas model developed for wide pore size distributions. The transport model is combined with local reaction kinetics to yield a differential equation problem. Interphase transport is described by a novel method which incorporates an arbitrary {dollar}j{dollar}-factor correlation into a multicomponent boundary layer treatment. The complete pellet representation is converted to an algebraic system by orthogonal collocation on finite elements. Plug flow reactor equations describing the flow mean state profiles are appended to the pellet equations and the composite differential-algebraic system is integrated by available software. The computational model is used to fit a multicomponent kinetic scheme to the heptane reforming data of Hettinger and coworkers. Kinetics derived from data for a single particle size are used to predict catalyst performance of other particle sizes. A comparison is made to the related pseudo-homogeneous model of Krane and coworkers.