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Separation of kinetics and mass‐transfer in a batch alkoxylation reaction
Author(s) -
Hall C. A.,
Agrawal P. K.
Publication year - 1990
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450680113
Subject(s) - chemistry , ethylene oxide , mass transfer , kinetics , catalysis , alcohol , reaction rate , drop (telecommunication) , reaction rate constant , mass transfer coefficient , chemical kinetics , coalescence (physics) , chemical engineering , chromatography , organic chemistry , copolymer , telecommunications , physics , quantum mechanics , astrobiology , computer science , engineering , polymer
The quantitative aspects of the role of interfacial mass‐transfer and reaction kinetics in ethoxylation of lauryl alcohol were examined in a batch recirculation reactor. The liquid droplets falling through a gas column were obtained by utilizing a recirculation loop and a set of spray nozzles. The CO 2 / NaOH reaction was employed to characterize the interfacial area. The alkoxylation reaction was studied at temperatures between 124°C and 171°C, at catalyst levels between 0.09 and 0.50 weight percent and at ethylene oxide partial pressures between 68 kPa and 204 kPa. A model was developed which permits the prediction of reactor performance at various operating conditions. The mass‐transfer during free fall dominates the interfacial mass‐transfer and the contributions during the drop formation and coalescence stages are small. The rate of ethylene oxide ( EO ) addition to lauryl alcohol was constant during the batch run, indicating similar activity for the unreacted lauryl alcohol and the lauryl alcohol ethoxylated to varying extents. The rate of ethoxylation is first‐order in both catalyst and ethylene oxide concentrations. The liquid‐phase reaction kinetics and interfacial mass‐transfer occur in series, with kinetics dominating the overall ethoxylation rate. As expected, an increasing role of mass transfer is observed at higher temperatures, and/or higher catalyst concentrations where the kinetic rate becomes significantly high. The intrinsic activation energy for the ethoxylation of lauryl alcohol is 55.2 kJ/mole.