Publicação
Thermodynamic equilibrium and reaction kinetics for the esterification of lactic acid with ethanol catalyzed by acid ion-exchange resin
| Resumo: | The heterogeneous catalysis of lactic acid (88 wt %) esterification with ethanol in the presence of Amberlyst 15-wet was studied for catalyst loading of 1.2-3.9 wt %, initial molar ratio of reactants of 1.1-2.8, and temperature from 50 to 90 °C. In this work a methodology based on the UNIQUAC model was developed to determine the thermodynamic equilibrium constant since in the literature there is inconsistency concerning the temperature dependence of the thermodynamic equilibrium constant. A simplified Langmuir-Hinshelwood kinetic model was used to predict the experimental data. The proposed rate law is r ) kc(aEthaLa - aELaW/ K)/(1 + KEthaEth + KWaW)2; the kinetic parameters are the preexponential factor, kc,0 ) 2.70 107 molâg-1âmin-1, and the activation energy, Ea ) 49.98 kJ/mol. The equilibrium reaction constant is K ) 19.35 exp(-515.13/T (K)) with reaction enthalpy 4.28 kJ/mol. The model reasonably predicts the kinetic experimental data, and it will be very useful to apply to the design and optimization of industrial hybrid reactive separation processes. |
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| Autores principais: | Pereira, Carla |
| Outros Autores: | Pinho, Simão; Silva, Viviana; Rodrigues, Alírio |
| Assunto: | Esterification Thermodynamics Kinetics Catalyst |
| Ano: | 2008 |
| País: | Portugal |
| Tipo de documento: | artigo |
| Tipo de acesso: | acesso restrito |
| Instituição associada: | Instituto Politécnico de Bragança |
| Idioma: | inglês |
| Origem: | Biblioteca Digital do IPB |
| Resumo: | The heterogeneous catalysis of lactic acid (88 wt %) esterification with ethanol in the presence of Amberlyst 15-wet was studied for catalyst loading of 1.2-3.9 wt %, initial molar ratio of reactants of 1.1-2.8, and temperature from 50 to 90 °C. In this work a methodology based on the UNIQUAC model was developed to determine the thermodynamic equilibrium constant since in the literature there is inconsistency concerning the temperature dependence of the thermodynamic equilibrium constant. A simplified Langmuir-Hinshelwood kinetic model was used to predict the experimental data. The proposed rate law is r ) kc(aEthaLa - aELaW/ K)/(1 + KEthaEth + KWaW)2; the kinetic parameters are the preexponential factor, kc,0 ) 2.70 107 molâg-1âmin-1, and the activation energy, Ea ) 49.98 kJ/mol. The equilibrium reaction constant is K ) 19.35 exp(-515.13/T (K)) with reaction enthalpy 4.28 kJ/mol. The model reasonably predicts the kinetic experimental data, and it will be very useful to apply to the design and optimization of industrial hybrid reactive separation processes. |
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