Triethyl citrate synthesis by reactive distillation

Aspi K. Kolah, Navinchandra S. Asthana, Dung T. Vu, Carl T. Lira, Dennis J. Miller

Research output: Contribution to journalArticle

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Abstract

A continuous reactive distillation process is proposed for the synthesis of triethyl citrate from citric acid and ethanol in the presence of macroporous Amberlyst 15 ion-exchange resin catalyst. The process design, developed using ASPEN Plus simulation software, is based on laboratory kinetic and thermodynamic studies and pilot-scale reactive distillation experiments. Pilot-scale experiments were carried out in a 5-m glass reactive distillation column; catalyst effectiveness was then determined from ASPEN Plus simulation of pilot-scale experiments using a user-written reaction kinetic module based on activity coefficients. Because citric acid esterification kinetics are slow, complete conversion could not be obtained in the pilot-scale column. Using parameters determined from simulation of a pilot-scale column experiment, design of a reactive distillation column to completely convert citric acid to triethyl citrate was carried out. Optimum column performance occurs at low reflux ratios (L/D <0.1) to avoid water reintroduction and at moderately elevated pressure (2.5 bar) to increase temperature and enhance kinetic rates without leading to product degradation. The effect of ethanol feed position and values of reflux and boilup ratios were also examined. A large number of reactive stages is required because of the slow reaction of diethyl citrate to triethyl citrate. As a final step, the design of a complete commercial-scale process to produce 25 million lbs/y triethyl citrate, with the reactive distillation column as the core component, was carried out. Three different process schemes were examined. In the first scheme, only a reactive distillation column is used. The second uses a prereactor followed by a reactive distillation column. In the third and preferred scheme, a prereactor followed by a simple distillation column to remove water is placed ahead of the reactive distillation column. In each configuration, triethyl citrate product yield is maintained above 98.5 wt %, with the main byproduct being diethyl citrate. Comparison of stream compositions and equipment design parameters is provided for the three schemes considered.

LanguageEnglish (US)
Pages1017-1025
Number of pages9
JournalIndustrial and Engineering Chemistry Research
Volume47
Issue number4
DOIs
StatePublished - Feb 20 2008

Profile

Distillation columns
distillation
Distillation
Citric acid
Citric Acid
citric acid
Kinetics
Ethanol
kinetics
ethanol
Ion Exchange Resins
experiment
Catalysts
catalyst
Ion exchange resins
ethyl citrate
Water
Experiments
Activity coefficients
Esterification

ASJC Scopus subject areas

  • Polymers and Plastics
  • Environmental Science(all)
  • Chemical Engineering (miscellaneous)

Cite this

Triethyl citrate synthesis by reactive distillation. / Kolah, Aspi K.; Asthana, Navinchandra S.; Vu, Dung T.; Lira, Carl T.; Miller, Dennis J.

In: Industrial and Engineering Chemistry Research, Vol. 47, No. 4, 20.02.2008, p. 1017-1025.

Research output: Contribution to journalArticle

Kolah, Aspi K. ; Asthana, Navinchandra S. ; Vu, Dung T. ; Lira, Carl T. ; Miller, Dennis J./ Triethyl citrate synthesis by reactive distillation. In: Industrial and Engineering Chemistry Research. 2008 ; Vol. 47, No. 4. pp. 1017-1025
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