Kinetic model based on a molecular description for catalytic cracking of vacuum gas oil

doi:10.1016/S0009-2509(05)80018-1

Chemical Engineering Science

Volume 49, Issue 24, Part A, 1994, Pages 4249-4262

https://doi.org/10.1016/S0009-2509(05)80018-1 Get rights and content

Abstract

A kinetic model based on a molecular approach is proposed to represent the cracking reactions of industrial feedstocks on a commercial equilibrium catalyst.

Special attention is given to the definition of lumps to represent correctly the effect of the feedstock composition on the gasoline composition through the most important reactions occurring between lumps. The latter are defined not only by their boiling range but also by their chemical composition.

The kinetic model is built from experiments with a small fixed bed reactor (the microactivity test). The analysis of cracked products is done by chromatography simulated distillation and a detailed gas chromatographic analysis of gases and gasoline. The study is done at 803 K with various reaction conditions (catalyst hold-up, initial catalyst coke content) to observe primary and successive products. Three typical commercial feedstocks (aromatic, naphthenic or paraffinic) are used to distinguish the effects of feedstock components.

The selected reactions are grouped as: (i) cracking reactions by β scission of paraffin, alkyl-aromatic or naphthenic chains, (ii) condensation reactions of olefins possibly with aromatic hydrocarbons, (iii) cyclization of olefins, (iv) hydrogen transfer reactions.

The attention is focused on the deactivation function of the catalyst. This function is experimentally determined by testing previously coked catalysts. It takes into account chemical deactivation by coke fouling and diffusional limitation due to pore plugging by coke. The results show that this function depends on the feedstock composition.

The reactor is modelled as isothermal, plug flow and unsteady because of the deactivation by coke. The kinetic expressions suppose generally an order one versus each reactant. The kinetic constants are determined by non-linear adjustment with experimental data.

The obtained set of kinetic constants describes satisfactorily the experimental results. The kinetic model shows the importance of the condensation and hydrogen transfer reactions for coke formation and gasoline quality. It can be used for modelling a commercial FCC riser.

References (34)

ForissierM. et al.
Deactivation of cracking catalyst with vacuum gas oil
ForissierM. et al.
Effect of total pressure on catalytic cracking reaction
Catal. Today
(1991)
JohnT. et al.
On identifying the primary and the secondary products of the catalytic cracking of neutral distillates
J. Catal.
(1975)
KraemerD.W. et al.
Catalytic cracking kinetics in a novel riser simulator
Chem. Eng. Sci.
(1990)
LiG. et al.
New approaches to determination of constrained lumping schemes for a reaction system in the whole composition space
Chem. Eng. Sci.
(1991)
MartinM.P. et al.
Catalytic cracking in riser reactor, core-annulus and elbow effects
Chem. Eng. Sci.
(1992)
VynckierE. et al.
Modeling of the kinetics of complex processes based upon elementary steps
ZhaoY. et al.
The chain mechanism in catalytic cracking. The kinetics of 2 methyl pentane cracking
J. Catal.
(1993)
ArisR.
Reactions in continuous mixtures
A.I.Ch.E.J.
(1989)
CorellaJ. et al.
A model for the riser of a FCC unit based on the kinetics of cracking and deactivation from lab tests

CorellaJ. et al.

Analysis of the riser reactor of a fluid cracking unit model based on kinetics of cracking and deactivation from laboratory tests

ACS. Symp. Ser

(1991)

CorellaJ. et al.

Variation with time of the mechanism, observable order and activation energy of the catalyst deactivation by coke in the FCC process

Ind. Eng. Chem. Process Des. Dev.

(1985)

CorellaJ. et al.

Pilot plant for the fluid catalytic cracking process: Determination of the kinetic parameters of deactivation of the catalyst

Ind. Eng. Chem. Proc. Des. Dev.

(1986)

CoxonP.G. et al.

Lumping strategy. 1. Introductory techniques and applications of cluster analysis

Ind. Eng. Chem. Res.

(1987)

FengW. et al.

Single-event kinetics of catalytic cracking

Ind. Eng. Chem. Res.

(1993)

Forissier, M., Magnoux, P., Rivault, P., Bernard, J. R. and Guisnet, M., to be...

FromentG.F.

Fundamental kinetic modeling of complex processes

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Kinetic model based on a molecular description for catalytic cracking of vacuum gas oil

Abstract

Catal. Today

J. Catal.

Chem. Eng. Sci.

Chem. Eng. Sci.

Chem. Eng. Sci.

J. Catal.

Reactions in continuous mixtures

A.I.Ch.E.J.

A model for the riser of a FCC unit based on the kinetics of cracking and deactivation from lab tests

Analysis of the riser reactor of a fluid cracking unit model based on kinetics of cracking and deactivation from laboratory tests

ACS. Symp. Ser

Variation with time of the mechanism, observable order and activation energy of the catalyst deactivation by coke in the FCC process

Ind. Eng. Chem. Process Des. Dev.

Pilot plant for the fluid catalytic cracking process: Determination of the kinetic parameters of deactivation of the catalyst

Ind. Eng. Chem. Proc. Des. Dev.

Lumping strategy. 1. Introductory techniques and applications of cluster analysis

Ind. Eng. Chem. Res.

Single-event kinetics of catalytic cracking

Ind. Eng. Chem. Res.

Fundamental kinetic modeling of complex processes