*2.2. Catalyst Preparation*

The known sol-gel methods were adapted for the preparation of the catalysts. Precursors Co and Ni acetates were thoroughly dried to eliminate the moisture content. Then they were ground and sieved to obtain particle sizes <100 µm. The total metal loading is 5 wt % of Co and/or Ni in the monometallic catalyst, while for the bimetallic the total metal loading was 5 wt % with 1:1 mole ratio. The Zr to Al atoms is also 1:1 mole ratio. For the preparation of 16.33 g of ZrO2–Al2O<sup>3</sup> with an equimolar ratio of Zr to Al, 48 g of Zr-butylate (equivalent to 11.32 g of ZrO2) and 25 g of Al-sec.-butylate (equivalent to 5.01 g of Al2O3) were placed in a 250 mL three-necked round glass bottom flask. The mixture was heated with continuous stirring to 130 ◦C. A lot of 2.59 g of dried Co acetate was added and the mixture was again heated for about two hours at the same temperature.

After completion, the reaction mixture was transferred into 75 g of isopropanol. A homogeneous solution was obtained with slightly pink color when using Co while it was faint green in presence of Ni. To this solution, 27 mL of distilled water were added immediately and the mixture was then refluxed for another hour. After cooling to room temperature, the precipitate was separated from the liquid with a glass frit. The obtained solid was first dried at room temperature overnight and then divided into two parts. One part was calcined under air at 550 ◦C for 5 h with a heating rate of 2 K/min. The other part of the solid was calcined at 800 ◦C under similar conditions. For simplicity, the catalyst names refer to their pre-treatment calcination temperature.
