Decoking of fixed‐bed catalytic reactors

Abstract

Dedicated to Pro5 Dr. Hanns Hofmann at the occasion of his 65th birthdayA mathematical model for the description of the non-steady state process of decoking of a fixed bed catalytic reactor is presented. The relevant dimensionless groups are identified and their influence on the process discussed. Appropriate relationships are given for the estimation of the maximum temperature in the bed. Methods of monitoring the process and of controlling it in the case of unknown or variable coke contents are explained.

Removal of Volatile Organic Compounds from Polluted Air in a Reverse Flow Reactor: An Experimental Study

“…Comparison of results calculated with eq 4 and measured results gave good agreement; see also Westerterp et al (1988). Influence of the Gas Velocity.…”

Influence of chemical reaction rate, diffusion and pore structure on the regeneration of a coked Al2O3-catalyst

“…It should be noted here that the pore diameter was used as the "fitting parameter" in the calculation (Eqs. (10) and (11)), subsequently denoted as d pore,num . If d pore,num is set to 15 nm, a good agreement with the experimental data is obtained (Fig.…”

“…So, during the unsteady process of coke burn-off, radial gradients of the O 2 -concentration and with proceeding burn-off also of the carbon content are established [7][8][9]. A description of coke burn-off by well known closed solutions like the homogeneous model or the shrinking core model is only reasonable for the border cases of complete control by chemical reaction or by pore diffusion (reaction is then confined to a front), respectively [9]; the same is true for models based on the assumption that only external mass transfer through the gas boundary layer controls the burn-off rate [10]. More complex solutions already consider pore diffusion and distinct concentration gradients of O 2 and carbon, but are still based on simplifications, e.g.…”

Three-phase packed bed reactor with an evaporating solvent—I. Experimental: the hydrogenation of 2,4,6-trinitrotoluene in methanol

“…11 the velocity of the reaction front can be calculated as 3.3 x 10m6 m/s for the section between the first and second detection points, and as 4.4 x 10V6 m/s for the section between the second and third detection points. Assuming that the burn-off reaction is C + 0, -+ COz, that the conversion rate of the deposits is limited by the interparticle mass transfer rate, that the reactor is adiabatic and that no axial dispersion of mass and heat occurs Westerterp et al (1984Westerterp et al ( , 1988 gave the following equation for the velocity Ufron, of the reaction front:…”