Central composite experimental design applied to the catalytic aromatization of isophorone to 3,5-xylenol

The aim of this study was to apply experimental design in the optimization of catalytic aromatization of isophorone to 3,5-xylenol to improve 3,5-xylenol selectivity. The central composite design was used to design an experimental program to provide data to model the effects of various factors on 3,5-xylenol selectivity (Y). The variables chosen were Cr2O3 loading (XI), reaction temperature (X-2) and LHSV (X-3). The mathematical relationship of 3,5-xylenol selectivity on the three significant independent variables can be approximated by a nonlinear polynomial model. Predicted values were found to be in good agreement with experimental values (R-Sq of 99.7% and R-Sq (adj) of 99.5% for response Y). The result of optimization predicted by the model showed that 3,5-xylenol selectivity presented the maximal result 86.7% at the optimal condition of Cr2O3 loading 15.5%, reaction temperature 560 degrees C, LHSV 1.46h(-1). This study has shown that central composite design could efficiently be applied for the modeling of catalytic aromatization of isophorone, and it is an economical way of obtaining the maximum amount of information with the fewest number of experiments. (c) 2007 Elsevier B.V. All rights reserved.