The NiW catalyst has demonstrated higher hydrogenating (HYD) capacity than typical hydrotreating (HDT) catalysts, NiMo and CoMo, therefore it possess potential for deep hydrodesulfurization (HDS) processes. Similar to Mo-based catalysts, NiW/Al2O3 solids exhibit surface phenomena that are detrimental to the formation of active phase, the so-called �Ni-W-S� phase. However, the concentration of Ni in the Ni-W-S phase has still not been optimized because NiSx segregation and nickel migration occur. In this sense, addition of complexing agents has shown to be beneficial on the catalytic activity in sulfide HDT catalysts. Firstly, the effect of 1, 2-cyclohexanediamine-N, N, N', N'-tetraacetic acid (CyDTA) incorporation in the synthesis of NiMo and CoMo catalysts has been studied, displaying significant increases in the promotion of MoS2 and consequently, obtaining improvements in HDS activity. Recently, some of us showed that control of pH of the nickel-citric acid solution had an important role over the modulation of metal-support interactions, achieving favorable conditions for the formation of the sulfide phase and reaching important increases in catalytic activity in the HDS of 4,6-dimethyldibenzothiophene (46DMDBT).In the present work, we investigated the effect of pH in Ni-CyDTA solution over the superficial metal-support interactions and the catalytic activity in HDS of 46DMDBT. The solutions and catalysts were characterized by FTIR, UV-Vis, XPS, TPR and HRTEM. A significant increase in catalytic activity for NiWS/Al2O3 was found when the Ni-CyDTA solution was impregnated at pH=4.0. According with characterization results, this increment has been related with the increase in NiWS species, promoted by the delay effect in the sulfidation of Ni. This effect was related with the presence Ni(CyDTA)2- complex. Also, a close correlation between the fraction of Ni-W-S species and catalytic activity in the HDS of 46DMDBT was observed.

Effect of 1,2-cyclohexanediamine-N,N, N', N'-tetraacetic acid as complexing agent in a hydrodesulfurization NiWS/Al<sub>2</sub>O<sub>3</sub> catalyst

248th National Meeting (2014)

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Effect of 1,2-cyclohexanediamine-N,N, N', N'-tetraacetic acid as complexing agent in a hydrodesulfurization NiWS/Al2O3 catalyst

Effect of 1,2-cyclohexanediamine-N,N, N', N'-tetraacetic acid as complexing agent in a hydrodesulfurization NiWS/Al₂O₃ catalyst