ACTIVATION AND REGENERATION OF A NIMO AL2O3 HYDROTREATMENT CATALYST/

Activation and regeneration procedures applied to a nickel-molybdenum on alumina catalyst, both fresh and spent, were tested by the hydrodes ulfurization of thiophene. Characterization techniques used included t emperature programmed reduction and oxidation (TPR, TPO), diffuse refl ectance spectroscopy (DRS), and X-ray diffraction (XRD). The fresh cat alyst was treated by sulfiding, reoxidation, and resulfiding. This seq uence was found to be more effective than one sulfiding step, possibly because of the formation of a nickel molybdate phase during reoxidati on. The spent catalyst could not be regenerated completely although it s original surface properties were attained. The loss of activity of t he spent catalysts was alluded by TPO to result from nickel-molybdenum segregation which probably happened because of the excessive heat fro m burning the coke present on the catalyst.