The application of the attainable region concept to the oxidative dehyrogenation of N-butanes in inert porous membrane reactors
Date
2009-04-02T13:10:48Z
Authors
Milne, Alan David
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Abstract
The availability of kinetic data for the oxidative dehydrogenation (ODH) of
n-butane from Téllez et al. (1999a and 1999b) and Assabumrungrat et al.
(2002) presented an opportunity to submit a chemical process of industrial
significance to Attainable Region (AR) analysis.
The process thermodynamics for the ODH of n-butane and 1-butene have
been reviewed. The addition of oxygen in less than the stoichiometric ratios
was found to be essential to prevent deep oxidation of hydrocarbon products
{Milne et al. (2004 and 2006c)}.
The AR concept has been used to determine the maximum product yields
from the ODH of n-butane and 1-butene under two control régimes, one
where the partial pressure of oxygen along the length of the reactor was
maintained at a constant level and the second where the oxygen partial
pressure was allowed to wane. Theoretical maxima under the first régime
were associated with very large and impractical residence times.
The Recursive Convex Control policy {Seodigeng (2006)} and the second
régime were applied to confirm these maxima {Milne et al. (2008)}. Lower
and more practical residence times ensued. A differential side-stream reactor
was the preferred reactor configuration as was postulated by Feinberg
(2000a).
Abstract
A.D. Milne Page 4 of 430
The maximum yield of hydrocarbon product, the associated residence time
and the required reactor configuration as functions of oxygen partial
pressure were investigated for the series combinations of an inert porous
membrane reactor and a fixed-bed reactor. The range of oxygen partial
pressures was from 85 kPa to 0.25 kPa. The geometric profile for
hydrocarbon reactant and product influences the residence times for the
series reactors.
The concept of a residence time ratio is introduced to identify the operating
circumstances under which it becomes advantageous to select an inert
membrane reactor in preference to a continuously stirred tank reactor and
vice versa from the perspective of minimising the overall residence time for
a reaction {Milne et al. (2006b)}.
A two-dimensional graphical analytical technique is advocated to examine
and balance the interplay between feed conditions, required product yields
and residence times in the design of a reactor {Milne et al. (2006a)}..
A simple graphical technique is demonstrated to identify the point in a
reaction at which the selectivity of the feed relative to a product is a
maximum {Milne et al. (2006a)}.
Literature Cited
Assabumrungrat, S. Rienchalanusarn, T. Praserthdam, P. and Goto, S.
(2002) Theoretical study of the application of porous membrane reactor to
Abstract
A.D. Milne Page 5 of 430
oxidative dehydrogenation of n-butane, Chemical Engineering Journal,
vol. 85, pp. 69-79.
Feinberg, M. (2000a) Optimal reactor design from a geometric viewpoint –
Part II. Critical side stream reactors, Chemical Engineering Science, vol. 55,
pp. 2455-2479.
Milne, D., Glasser, D., Hildebrandt, D., Hausberger, B., (2004), Application
of the Attainable Region Concept to the Oxidative Dehydrogenation of 1-
Butene in Inert Porous Membrane Reactors, Industrial and. Engineering
Chemistry Research, vol. 43, pp. 1827-1831 with corrections subsequently
published in Industrial and Engineering Chemistry Research, vol. 43,
p. 7208.
Milne, D., Glasser, D., Hildebrandt, D., Hausberger, B., (2006a), Graphical
Technique for Assessing a Reactor’s Characteristics, Chemical Engineering
Progress, vol. 102, no. 3, pp. 46-51.
Milne, D., Glasser, D., Hildebrandt, D., Hausberger, B., (2006b), Reactor
Selection : Plug Flow or Continuously Stirred Tank?, Chemical Engineering
Progress. vol. 102, no. 4, pp. 34-37.
Milne, D., Glasser, D., Hildebrandt, D., Hausberger, B., (2006c), The
Oxidative Dehydrogenation of n-Butane in a Fixed Bed Reactor and in an
Inert Porous Membrane Reactor - Maximising the Production of Butenes
and Butadiene, Industrial and Engineering Chemistry Research vol. 45,
pp. 2661-2671.
Abstract
A.D. Milne Page 6 of 430
Milne, D., Seodigeng, T., Glasser, D., Hildebrandt, D., Hausberger, B.,
(2008), The Application of the Recursive Convex Control (RCC) policy to
the Oxidative Dehydrogenation of n-Butane and 1-Butene, Industrial and
Engineering Chemistry Research, (submitted for publication).
Seodigeng, T.G. (2006), Numerical Formulations for Attainable Region
Analysis, Ph.D. thesis, University of the Witwatersrand, Johannesburg,
South Africa.
Téllez, C. Menéndez, M. Santamaría, J. (1999a) Kinetic study of the
oxidative dehydrogenation of butane on V/MgO catalysts, Journal of
Catalysis, vol. 183, pp. 210-221.
Téllez, C. Menéndez, M. Santamaría, J. (1999b) Simulation of an inert
membrane reactor for the oxidative dehydrogenation of butane, Chemical
Engineering Science, vol. 54, pp. 2917-2925.
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Description
Keywords
Attainable region, Oxidative dehydrogenation, Recursive convex control, Butane, Differential side-stream reactor