The circulating moving bed is an innovative coupled reactor for producing linear alkyl benzenes. It can be used with shorter life span catalysts compared to traditional fixed bed reactors. A model is developed in which the effect of catalyst deactivation on the reaction is simulated using infinitesimal balance equations. The results of step changes between steady states and unsteady states have been calculated with the model.

Reactor modeling of an innovative liquid-solid circulating moving bed for the synthesis of linear alkyl benzenes

Catalytic decomposition reactions performed in the chromatographic moving-bed reactor

The behaviour of the moving bed catalytic reactor is studied under the conditions when a reactant A is adsorbed on the countercurrently moving solid catalyst, reacts on its surface irreversibly to form a product B which is rapidly desorbed into a fluid phase. Local adsorption equilibrium of arbitrary form is assumed. The reaction may have any kinetics. The equations derived allow to calculate the length of the reactor required for any conversion. It is also shown that there exists a critical parameter σ such that the behaviour of the moving bed is similar to that of the fixed bed if 0 < σ < 1. This parameter is the maximum of the ratio of the equilibrium fluxes of the two phases. The results are illustrated on the example of the Fowler-Guggenheim adsorption isotherm.

Design equations and transient behaviour of the counter-current moving bed chromatographic reactor

The steady-state behavior of an isothermal countercurrent moving bed adsorber is analysed with the assumption that only one component is appreciably adsorbed, and adsorption can be described by a Langmuir isotherm. The behavior of the system is observed to depend critically on the parameter a, which is the ratio of the flux of matter in the solid phase to that in the fluid when the two phases are at equilibrium at low concentrations. When 0< a< 1 the qualitative behavior of the system is the same as that of a fixed bed (σ = 0). It is when σ ≥ 1 that the true countercurrent nature of the adsorber comes into play. When the adsorption-desorption rate is finite the dimensionless length of the adsorber can be readily expressed in terms of an integral, whose evaluation is performed for physically meaningful conditions of the inlet streams. When adsorption-desorption equilibrium is instantaneously achieved the problem is overdetermined and one or more discontinuities have to be introduced in the concentration pr...

Dmitry Altshuller

Papers

Design equations and transient behaviour of the counter-current moving bed chromatographic reactor

An analysis of a countercurrent adsorber