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New CoMo/Zn-Al mixed oxide catalysts were synthesized, characterized and tested in the HDS reaction of thiophene. Catalytic supports were synthesized by using variable (Al)/(Al ? Zn) mol ratios from 0.0 to 1.0, then, these supports were calcined up to 450°C and finally impregnated with Mo and Co, and calcined at 450°C again. Before impregnation, these solids were characterized by XRD and FT-IR, and after impregnation, by BET surface area measurements and temperature programmed reduction (TPR). Results showed that the hydrotalcite phase is formed between 0.20 and 0.33 (Al)/(Al ? Zn) mol ratios. At increasing Al content, an Al 2 O 3 phase (b-Al 2 O 3 ) emerges together with the hydrotalcite phase which diminishes as Al content increases. Results corresponding to the thiophene HDS reaction showed a catalytic activity maximum at 0.25 ratio; then, the catalytic activity decreased with Al content. These results could be associated with an optimum combination of Al and Zn oxides in which their properties are complemented.

A hydrocalumite-type material (HC) was synthesized by the co-precipitation method, mixing Ca and Al nitrate solutions in a NaOH solution (pH ≅ 11). This solid was characterized by using different physico-chemical techniques such as: Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), temperature programmed reduction (TPR) and BET surface area measurements. Then, a portion of as-synthesized solid was calcined at 420 ºC (HC 420). Both calcined and pristine solids were impregnated with Mo (15% w/w as MoO 3 ). Ni or Co was also impregnated on Mo/HC or Mo/HC 420 in 1(Co or Ni):3 (Mo) atomic ratios to get catalytic precursors. These solids were also characterized by the above mentioned techniques. Catalytic precursors were tested in the thiophene hydrodesulfuration reaction at 280 ºC and atmospheric pressure. Cobalt promoted catalysts were more active than those promoted with Ni. However, thiophene conversions were lower than that of a conventional CoMo/γ-Al 2 O 3 catalyst.