Effects of the activation method on the performance of base metal catalysts prepared by wet impregnation for toluene hydrogenation in liquid phase
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The present work aims to study the effects of the activation method on the performance of base metal catalysts for toluene hydrogenation in liquid phase. For this, catalysts of Fe, Co and Ni supported on γ-Al2O3 were prepared by wet impregnation from chlorinated precursors and reduced by formaldehyde. The prepared catalysts were activated ex situ at 773 K or in situ at 523 K both under H2 and characterized by N2 physisorption, SEM + EDX, TEM, XPS and TPR techniques. Catalytic tests were conducted in a slurry Parr reactor at 373 K under H2 pressure of 5 MPa. The results indicate the formation of metal hydroxides during the catalysts preparation, which are not reduced by the formaldehyde. The ex situ activation seems able to reduce both hydroxides of Fe and Ni, but there is no evidence of reduction in the case of Co hydroxide. Co and Ni catalysts present higher activities when not activated, whereas the in situ activation increases the activity of the Fe catalyst.
KeywordsBase metals Alumina Wet impregnation Toluene hydrogenation
To the “National Counsel of Technological and Scientific Development” (CNPq) for the financial support and research scholarship granted to Raphael Soeiro Suppino.