Dynamic Modeling and Simulation of Heavy Paraffin Dehydrogenation Reactor for Selective Olefin Production in Linear Alkyl Benzene Production Plant

Modeling of a heterogeneous industrial fixed bed reactor for selective dehydrogenation of heavy paraffin with Pt-Sn- Al2O3 catalyst has been the subject of current study. By applying mass balance, momentum balance for appropriate element of reactor and using pressure drop, rate and deactivation equations, a detailed model of the reactor has been obtained. Mass balance equations have been written for five different components. In order to estimate reactor production by the passage of time, the reactor model which is a set of partial differential equations, ordinary differential equations and algebraic equations has been solved numerically. Paraffins, olefins, dienes, aromatics and hydrogen mole percent as a function of time and reactor radius have been found by numerical solution of the model. Results of model have been compared with industrial reactor data at different operation times. The comparison successfully confirms validity of proposed model.

Authors:

• G. Zahedi
• H. Yaghoobi

Keywords:

• Dehydrogenation
• fixed bed reactor
• modeling
• linear alkyl benzene.

References:

[1] M.M. Bhasin, J.H. McCain, B.V. Vora, T. Imai, P.R. Pujad'o,
"Dehydrogenation and oxydehydrogenation of paraffins to olefins",
Applied Catalysis A: General 221 (2001) 397-419.
[2] Z. Mansourpour, S. Sahebdelfar, M. Saeedizad, "Study of Pt-Sn/Al2O3
Catalyst Deactivation Kinetic in Dehydrogenation of Normal Paraffin",
National Petrochemical Company, Research & Technology, Tehran,
Iran, 2006.
[3] G. Padmavathi, K.K. Chaudhuri, D. Rajeshwer, G. Sreenivasa Rao, K.R.
Krishnamurthyb, P.C. Trivedic, K.K. Hathic, N. Subramanyamc"
Kinetics of n-dodecane dehydrogenation on promoted platinum
catalyst", Chemical Engineering Science 60 (2005) 4119 - 4129.
[4] Bistoon petrochemical complex, IFP manual, 2005.
[5] P. Ciambelli, A. Di Benedetto, R. Pirone, G. Russo, "Spontaneous
isothermal oscillations in N2O catalytic decomposition: fixed-bed
reactor modeling", Chemical Engineering Science 54 (1999) 4521-
4527.
[6] M. Mohagheghi, Gh. Bakeri, M. Saeedizad, "Study of External and
Internal Diffusion Effects on Propane Dehydrogenation Reaction over
Pt-Sn/Al2O3 Catalyst", National Petrochemical Company, Research &
Technology, Tehran, Iran, 2006.
[7] R. B. Bird, W. E. Stewart, E. N. Lightfoot, "Transport Phenomena",
John Wily Press, Second Edition, New York, 2002.
[8] McDonald, Stuart "Finite Difference Approximation for Linear
Stochastic Partial Differential Equations with Method of Lines", Social
and Information Systems Laboratory, California Institute of Technology,
2006.
[9] Bistoon petrochemical complex longsheet, 2006-2007.
[10] R. E. Treybal, "Mass Transfer Operation", Third Edition,
[11] J .M. Prausnitz, R. N. Lichtenthaler, E. G. de Azevedo, "Molecular
Thermodynamics of Fluid-Phase Equilibria", Second Edition,
[12] A. Kharrab, R. B. Gaunter, "Numerical Analysis with MATLAB",
[13] O. Levenspiel, "Chemical Reaction Engineering",
[14] N. George, B.V. Kamath, A.G.Basrur, K. R. Krishnamurthy, "Role of
Hydrogen in Catalytic Dehydrogenation: Film Diffusion Controlled
Deactivation", React. Kinet. Catal. Lett, Vol. 60, No.2, 379-386.
[15] D. T. Gokak, A. G. Basrur, D. Rajeswar, G. S. Rao, K. R.
Krishnamurthy, "Lithium Promoted Pt-Sn/Al2O3 Catalysts For
Dehydrogenation of n-Decane: Influence of Lithium Metal Precursors",
Reac. Kinet. Catal. Lett. Vol. 59, No.2, 315-323, 1996.
[16] N. A. Gaidai and S. L. Kiperman, "Kinetic Models of Catalyst
Deactivation in Paraffin Dehydrogenation", Kinetics and Catalysis, Vol.
42, No. 4, 2001, pp. 527-532. Translated from Kinetika i Kataliz, Vol.
42, No. 4, 2001, pp. 581-587. Original Russian Text Copyright ┬® 2001
by Gaidai, Kiperman.
[17] P. Ciambelli, A. Di Benedetto, R. Pirone, G. Russo, "Spontaneous
isothermal oscillations in N2O catalytic decomposition: fixed-bed
reactor modeling", Chemical Engineering Science 54 (1999) 4521-4527.
[18] M. Bowker, T. Aslam, M. Roebuck, M. Moser, "The effect of coke laydown
on n-heptane reforming on Pt and Pt-Sn catalysts", Applied
Catalysis A: General 257 (2004) 57-65.
[19] Karine Surla, HankVleeming, Denis Guillaume, Pierre Galtier, "Asingle
events kinetic model: n-butane isomerization", Chemical Engineering
Science 59 (2004) 4773 - 4779.
[20] Ivano Miracca, Laura Piovesan, "Light paraffins dehydrogenation in a
fluidized bed reactor", Catalysis Today 52, (1999), 259-269.
[21] C. Audo, J.F. Lambert, M. Che, B. Didillon, "Synthesis of platinum-
tin/alumina reforming catalysts from a well-defined platinum-tin
precursor complex", Catalysis Today 65, (2001), 157-162.
[22] P. Praserthdam, N. Grisdanurak, W. Yuangsawatdikul," Short
communication Coke formation over Pt-Sn-K/Al2O3 in C3, C5-C8
alkane dehydrogenation", Chemical Engineering Journal 77 (2000) 215-
219
[23] K. Kumbilieva, N.A. Gaidai, N.V. Nekrasov, L. Petrov, A.L. Lapidus,
"Types of active sites and deactivation features of promoted Pt catalysts
for isobutane dehydrogenation", Chemical Engineering Journal 120,
(2006), 25-32.