280873 Sizing of a Packed Reactive Distillation Column for Isoamyl Butyrate Production Using an Equilibrium Model

Thursday, November 1, 2012: 10:10 AM
Shadyside (Omni )
Jairo A. Duran1, Karen A. Cañon-Rubio1, Alejandro Lopez Gomez2, Alvaro Orjuela1 and Gerardo Rodriguez3, (1)Department of Chemical and Environmental Engineering, Universidad Nacional de Colombia, Bogota, Colombia, (2)Departament of Chemical and Environmental Engineering, Universidad Nacional de Colombia, Bogota, Colombia, (3)Departamento de Ingeniería Química y Ambiental, Universidad Nacional de Colombia, Bogotá, Colombia

Sizing of a Packed Reactive Distillation Column for Isoamyl Butyrate Production Using an Equilibrium Model

Jairo Duran, Karen Cañon, Alejandro López, Álvaro Orjuela

Grupo de Procesos Químicos y Bioquímicos. Department of Chemical and Environmental Engineering. Universidad Nacional de Colombia. Bogotá. Colombia

Reactive distillation has been considered as an alternative for sustainable process in the production of green chemicals because their capabilities of reaching high conversion in equilibrium reactions, flexibility and relatively low costs. Several studies have pointed the importance of taking into account high-quality thermodynamic and kinetic parameters in order to obtain reliable estimations on the performance of the integrated reaction-separation operation. Among different biobased esters, isoamyl butyrate that is used as green solvent and food additive can be obtained from renewable raw materials. For instance, fermentation broths from fuel ethanol production contain up to 2.5% (volume basis) of amyl alcohols which are currently blended with fuel ethanol or used as fuel for steam boilers. As a potential upgrading alternative, these alcohols can be esterified with different acids using a reactive distillation scheme to improve reaction conversions and energy savings with respect to the traditional esterification processes.

In this work, kinetic and phase equilibrium parameters from experimental data were used to simulate and size a reactive distillation column. NRTL and Hayden O'Connell models from regressed experimental data were used in phase equilibrium calculations. Kinetics was measured in a batch reactor using Amberlyst® 35 as catalyst. A full factorial design was established to carry out the kinetic tests. Experimental data were fitted adequately with a pseudo-homogeneous model. In addition, autocatalytic kinetics was measured using an identical methodology. The module RADFRAC of Aspen Plus® was used in modeling of reactive distillation. A basis of 200.000 kg per year of isoamyl butyrate (food grade, >99% weight) was considered in sizing and sensibility analyses. Amberlyst® 35 contained in KATAPAK SP-11® was considered in the simulation. MELLAPAK-250Y® was used in non catalytic packing sections, where autocatalytic kinetics was considered. Column height was calculated assuming an HETP of 0.5 meters, as reported by several authors.   

According with simulation results a conversion of butyric acid higher than 96% was possible. Nevertheless, including a pre-reactor in the scheme, a conversion higher than 99.1% was observed. Best performance of operation was found when using a mole excess around 1.5 of isoamyl alcohol to butyric acid in the system.

Keywords: reactive distillation, esterification, catalytic packing, ion exchange resin, flooding factor.


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