Study of the Individual Reactions of Hydrodesulphurization of Dibenzothiophene and Hydrogenation of 2-Methylnaphthalene
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Study of the Individual Reactions of Hydrodesulphurization of Dibenzothiophene and Hydrogenation of 2-Methylnaphthalene on ZnNiMo/c-Alumina Catalysts Carlos F. Linares Æ Maria´ngel Ferna´ndez
Received: 1 July 2008 / Accepted: 22 August 2008 / Published online: 23 September 2008 Ó Springer Science+Business Media, LLC 2008
Abstract A series of ZnNiMo/c-alumina catalysts with variable Zn/(Ni ? Zn) ratio were synthesized. These catalysts were characterized by chemical analysis, temperature programmed reduction (TPR) and BET surface area. After that, these catalysts were tested in the individual reactions of hydrodesulphurization (HDS) of dibenzothiophene (DBT) and hydrogenation (HYD) of 2methylnaphthalene (2MN). The results showed an increment of the catalytic activity, for both reactions, when the catalysts were doubly promoted with Ni and Zn in comparison to those mono-promoted catalysts. Keywords Dibenzothiophene 2-Methylnaphthalene Hydrotreating
1 Introduction Generally, the combustibles pool contains undesirable compounds as sulfur and nitrogen. Some of them can be refractory and difficult to remove them from crude oil fraction as diesel. So, sulfur and nitrogen compounds, upon combustion, are converted to SOx and NOx which produce the acid rain; while the reduction of aromatic compounds improves combustion characteristics of diesel by increasing the cetane number [1–5]. Much effort has been carried out to eliminate these heteroelements in order to satisfy the environmental regulations. Hydrotreating (HDT) reactions are usually employed because they are very effectives and
C. F. Linares (&) M. Ferna´ndez Laboratorio de Cata´lisis y Metales de Transicio´n, Facultad de Ciencias y Tecnologı´a, Departamento de Quı´mica, Universidad de Carabobo, Valencia, Carabobo, Venezuela e-mail: [email protected]
their technology is very well known. However, the quality of oil crude is more and more poor, and their refinement is much more difficult. New catalysts must be employed to obtain high conversions and selectivities, but several of them, can be very expensive or difficult to synthesize them. In that way, traditional catalysts (Co or Ni (Mo)/c-alumina) have been promoted with a third metal as Zn, Sn, Ti, Cr, V, Zr, Fe, etc. [6]. Some of them have an electronic effect and other a geometric effect, as for instance Zn [7, 8]. Zn has been used as a structural promoter on Co(Ni)Mo/c-alumina catalysts, and it has reported a markedly synergetic effect in hydrodesulphurization (HDS) reactions. The partial addition of Zn to traditional catalysts (CoMo/c-alumina and NiMo/c-alumina) is an easy way to synthesize catalysts cheaper (due to partial substitution of Ni or Co by Zn) and to improve successfully catalytic behavior of them. Zn can occupy the tetrahedral sites of alumina diminishing the amount of tetrahedral Ni2? or Co2? which are inactive in hydrotreating reactions [9–12]. Likewise, we have successfully recovered Ni from cellular phone batteries, and have used it in the synthesis of HDT ZnNiMo/c-alumina catalysts. Reac
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