II.1.1. Preparation of the Cu-Co / Zn-La catalysts – CoCuZnLa-CM

The ZnO-La₂O₃ support was prepared by precipitation of zinc nitrate and lanthanium nitrate with aqueous solution of urea. 32.89 g of Zn(NO₃)₂*6H₂O, 2.66 g of La(NO­₃)₂*6H₂O and 17.53 g of urea were dissolved into 400ml of water and the mixture was heated gradually to 95 °C under stirring and kept at this temperature for 4 h. After filtration and thorough washing with distilled water, the precipitate was dried at 80 °C for 12 h, and finally calcined at 350 °C for 1 h in air. 10 g of support were thus prepared.

Catalysts were prepared by incipient wetness impregnation at room temperature. 5 ml of aqueous solution containing the necessary amount of Co(NO₃)₂*6H₂O and Cu(NO₃)₂*6H₂O were used for impregnation of 2.1 g of support. The sample was dried at 80 °C overnight and then calcined at 350 °C for 4 h.

3 g of 15% Cu – 15% Co / 90% ZnO – 10% La₂O₃ catalyst were prepared.