CHARACTERIZATION OF CuO/Al2O3 CATALYSTS USED IN THE OXIDATION OF PHENOL SOLUTIONS

FENOGLIO; ROLANDI; MASSA; GONZALEZ; HAURE

Santa Fe, Argentina

Congreso; 3rd MERCOSUR Congress on Process Systems Engineering and 1st MERCOSUR Congress on Chemical Engineering; 2001

This work aims to find the proper catalyst for the oxidation of organic compounds in wastewater.  The results discussed are just a part of a more extensive research carried out.  Copper oxide catalysts supported on gamma alumina were synthesized using a molten salt method developed in our laboratory and calcined in air at different temperatures.  The samples were characterized using the following techniques: Atomic Absorption (AA), X-Ray Diffraction (XRD), Temperature Programmed Reduction (TPR) and BET Superficial Area.  The catalytic behavior for the oxidation of phenol aqueous solutions (5000 ppm) was also tested in a semibatch reactor, at temperatures between 120- 140°C and 6 atmospheres of oxygen pressure.   XRD and TPR results showed a single CuO phase present in the catalysts calcined at low temperature.   Higher calcination temperatures favored the formation of a bulk CuAl2O4  phase.  After several runs both catalysts decreased their activity.   The solubilization of the CuO phase in the acid aqueous reaction media could explain the activity decrease in the catalyst calcined at low temperature.  This phenomena was less importante in the catalyst reduced at high temperature, where several TPR profiles allowed us to conclude that a comigration into the support and further reaction to CuAl2O4 was the major effect that lead to the deactivation. The catalytic performance of both catalysts was compared and copper oxide was identified as the component that is related to the catalytic activity.