Engineering Aspects of Catalytic Cracking

1988

Accompanying the fast burning of coke on a cracking catalyst is the oxidation of the coke burning product, carbon monoxide. This carbon monoxide combustion involves a homogeneous and a catalytic reaction. The homogeneous reaction was isolated by injecting pulses of CO, CO2 and O2 into a laboratory scale reactor at controlled temperature and pressure. The coke burning and catalytic CO combustion reactions were studied by oxidizing coke deposited on a zeolitic catalyst in the same microcatalytic reactor. The role of homogeneous CO oxidation during coke combustion under these conditions was determined.

mentioning

confidence: 99%

Regeneration of cracking catalyst influence of the homogeneous CO postcombustion reaction

Morley

1988

“…Current technology for catalytic cracking involves sophisticated reactors where highly active catalysts are contacted with hydrocarbon feedstocks for a few seconds. Reliable kinetic data and catalyst preconditioning methods at the reaction conditions of riser cracking are needed for further improvement and technical innovations in the actual system (Campagna et al 1986;Upson et al 1982;de Lasa, 1982de Lasa, , 1984.…”

mentioning

confidence: 99%

Modelling the kinetics of fast catalytic cracking reactions

Collyer¹,

Larocca

1989

Instantaneous kinetic constants and gasoline selectivities have been determined for catalytic cracking of n‐hexadecane. The pulse technique was used in order to model the sequential build‐up of coke which occurs on cracking catalyst within a riser transport‐line reactor. The total amount of hydrocarbon injected per unit weight of catalyst was between 0 and 10. The mathematical model used to analyze the data was based on the unsteady state mass balance of the microcatalytic reactor with the assumption of plug flow. Results suggest a fast deactivation process during the run with fresh catalyst, while regenerated catalyst showed a slower deactivation. The catalyst regenerated three times evidenced a low apparent activation energy when temperature was increased from 500°C to 550°C.

“…Effective modeling of the regeneration reaction in laboratory or bench scale units is closely related to the improvement in design and operation of the commercial catalytic cracking regenerator units. For approprite simulation of large scale regenerators, a direct measurement of combustion kinetic parameters is normally advised (de Lasa, 1982(de Lasa, , 1984.…”

mentioning

confidence: 99%

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

Morley

1987

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.