**3. Experimental Section**

#### *3.1. Preparation of Fresh Catalyst*

A wet-impregnation technique was used to prepare a combined 15%Co–30%Fe supported on alumina catalyst. The synthesis steps are described as follows:

Alumina (γ-Al2O3; SA6175) were obtained from Norton Chemical Company (Short Hills, NJ, USA). The alumina were disintegrated into tiny particles before being employed as a ultimate support material. A first solution was prepared from a certain volume of double-distilled water and stoichiometric ferric nitrate amount (Fe(NO3)3·9H2O, Ass. ≥ 99%, Sigma-Aldrich, Taufkirchen, Germany). Dissolving a certain mass of cobalt nitrate (Co(NO3)3·9H2O, Ass. ≥ 99%, Sigma-Aldrich, Taufkirchen, Germany) in double-distilled water, a second solution was obtained. As in a typical wet-impregnation procedure, the two solutions of Co2+ and Fe3+ were simultaneously impregnated on the γ-Al2O3 support. The mixture was stirred at 80 ◦C for 3 h. After the stirring/heating step, more than 50% of the water contained in the mixture–solution evaporated. The final mixture was dried at 120 ◦C for 12 h (without washing) and followed by calcination at 450 ◦C for 3 h under air atmosphere. The mixed catalyst was designated as 15Co–30Fe/Al2O3.
