The catalytic hydrogenation of aromatic nitro ketone in a microreactor: Reactor performance and kinetic studies

Sunitha Tadepalli, Adeniyi Lawal

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Catalytic hydrogenation of nitro aromatics is an important class of reactions in the pharmaceutical and fine chemical industries. These reactions are extremely fast and highly exothermic in nature; hence, mass and heat transfer limitations play an important role when these reactions are conducted in conventional batch reactors. The use of a micro-channel reactor for such reactions provides improved mass transfer rates which may ensure that the reaction operates close to intrinsic kinetics. In the present study, the hydrogenation of a model aromatic nitro ketone was conducted in a packed-bed microreactor. The effects of different processing conditions were studied using 5%Pd/Alumina catalyst, viz.: hydrogen pressure, substrate concentration, temperature, and residence time on the conversion of substrate, Space Time Yield (STY), and selectivity of product. Internal and external mass and heat transfer limitations in the microreactor were examined. The kinetic study was undertaken in a differential reactor mode, keeping the conversion of the reactant at less than 10%. The overall reaction was treated as comprising two separate reactions: first, the reduction of the nitro compound to hydroxylamine and then, the reduction of the hydroxylamine to amine. Two rate equations for the two consecutive reactions assuming the Langmuir-Hinshelwood mechanism provided the best fit to the experimental data. These two rate equations predicted the experimental rates satisfactorily and the differences were within 10% error. Experiments were also carried out in an integral reactor, and the reactor performance data were found to be in agreement with the predictions of the theoretical models.

Original languageEnglish
Article numberA112
JournalInternational Journal of Chemical Reactor Engineering
Volume6
StatePublished - 2008

Keywords

  • Catalytic hydrogenation
  • Kinetics
  • Nitro aromatics
  • Packed-bed microreactor
  • Reactor modeling

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