Modelagem e validaÃÃo do processo contÃnuo de produÃÃo depoliÃis em reator de leito gotejante

AUTOR(ES)

Ana CÃssia da Silva Cabral

DATA DE PUBLICAÇÃO

2006

RESUMO

In the present work a trickle-bed reactor was employed in order to perform a saccharide hydrogenation process to produce polyols in the presence of a nickel catalyst supported on activated carbon. The catalyst was prepared, characterized and tested. The reactor was assembled charged with the catalyst and the proposed reactions performed. A model was then proposed and its simulation and validation were performed. The chosen saccharides were glucose, xylose, and lactose and their hydrogenations were performed in the trickle-bed reactor with 700 g of catalyst, Ni (4.81%)/C, at 393K, and 423K under a pressure of 10 bar of hydrogen and with a gas flow rate of 300 L/h and a liquid flow rate of 5 L/h. The behavior of the processes were described by heterogeneous models supposing steady state, uniform flux with axial dispersion, partial wetted catalytic bed, and the reaction of the Langmuir-Hinshelwood type. In the present work non linear models formed by systems of differential equations linked to heterogeneous reaction rates, were developed. The equations of the model were solved by the line method (LM), and concentration profiles of the saccharides and polyols along the reactor were generated. The hydrogenation processes of glucose and xylose produced a conversion of 24.64% for hexose with a 12.92%yield of sorbitol and a conversion 17.21% for pentose with a 17.50% yield of xilitol. The conversion of lactose was 14.90% with a yield of monosaccharides and lactitol of 17.67% and 26.48% respectively. The produced alcohol are polyhydroxilated with high added value and may be used as substitutes for sucrose and other carbohydrates in several industries such as food, cosmetics, and pharmaceuticals. Considering the importance of the production of these polyols, the continuous was compared with the bacth process and it was noticed that the trickle-bed production of sorbitol was 35.31 times higher, the xilitol production 6.39 times and lactitol 12.23

ASSUNTO(S)

trickle-bed reactor modelagem e validaÃÃo do processo reator de leito gotejante modeling and validation of the process hidrogenaÃÃo de sacarÃdeos saccharide hydrogenation engenharia quimica

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