On the determination of kinetic parameters for the regeneration of cracking catalyst

Abstract

In the study of the regeneration of cracking catalyst, two approaches may be taken when determining the kinetic rate constant for the coke combustion reaction. A global coke burning rate equation may be considered, based on the observed oxygen concentration and carbon dioxide to carbon monoxide molar product ratio. This reaction may also be represented by an intrinsic coke burning equation which is a function of the oxygen concentration and the carbon dioxide to carbon monoxide molar ratio at the reaction site, combined with a carbon monoxide postcombustion equation. It is proposed in this paper that the rate constant for intrinsic coke burning, kc, is essentially equal to the global coke burning rate constant, kc, and that its value is independent of the rate equation chosen for the carbon monoxide post‐combustion reaction.

Regeneration of cracking catalyst influence of the homogeneous CO postcombustion reaction

“…As was demonstrated recently by Morley and de Lasa (1987), it can be predicted from theoretical considerations that the value of the coke combustion rate constant is independent of the rate equation chosen for the carbon monoxide oxidation reaction. Thus, the coke burning rate constant, k c , was not affected by the model for homogeneous CO combustion.…”

“…The set of equations representing the mass balances of 02, CO and C02 in the catalytic bed is similar to that developed for homogeneous CO oxidation. However, as proposed by Morley and de Lasa (1987), the oxygen mass balance in a microcatalytic reactor containing a weakly promoted catalyst (1 100 p.p.b. of Pr) was modified to include a coke combustion term along with a catalytic CO combustion term.…”

“…It is the objective of the present study to establish first a suitable kinetic equation for homogeneous CO oxidation in a pulse microcatalytic reactor. It is also the goal of this contribution to determine if the homogeneous reaction has no significant effect on the catalyst regeneration kinetics as previously assumed in studies dealing with the fast regeneration of zeolitic catalyst in a microcatalytic reactor (Morley and de Lasa, 1987).…”

Coke steam reforming in FCC regenerator: A new mastery over high coking feeds

“…A reaction similar to coke steam gasification is the combustion of coke on the catalyst. This reaction has been extensively studied [25][26][27][28][29]. It has been shown that, in most cases, the kinetics of coke combustion at temperatures of 500-600ºC follow with first order kinetics, even considering over 80% coke removal in less than 5 minutes [25].…”

Modelling catalyst regeneration in an industrial FCC unit

“…The earliest models were single-phase, simplecontacting model with plug flow, and dispersion of reacting components with tanks in series (Arthur, 1951;Rowe & Patridge, 1965;Weiz & Godwin, 1966). Several workers (Weiz & Godwin, 1966;Morley & De-Lasa, 1987;Morley & De-Lasa, 1988) carried out extensive studies on the kinetics of coke burning reactions for zeolite catalyst and estimated the kinetic parameters for the process but did not apply the kinetic parameters to simulate industrial FCC regenerator. Other workers (De-Lasa et al, 1981;Errazu et al, 1979;Krishnaiah et al, 2007) performed steady-state analysis of the regenerator using the two-phase theory (bubblephase rich in gases, and emulsion-phase rich in catalyst particles).…”