PH value | Calcination | Drying | Citric acid to total metals molar ratio | Cu-Cr ratio | Sample No. |
3.32 | 3 hrs in 700˚C | 2 hrs in 160˚C | 2:1 | 0.05 | 1 |
5 | 3 hrs in 700˚C | 2 hrs in 160˚C | 2:1 | 0.05 | 2 |
7 | 3 hrs in 700˚C | 2 hrs in 160˚C | 2:1 | 0.05 | 3 |
9 | 3 hrs in 700˚C | 2 hrs in 160˚C | 2:1 | 0.05 | 4 |