Levels | ||||||
Variable | Coding | −1.68 (−α) | −1 | 0 | 1 | +1.68 (+α) |
Catalyst loading (wt%) | X1 | 0.26 | 0.4 | 0.6 | 0.8 | 0.96 |
Reaction temperature (˚C) | X2 | 46.6 | 50 | 55 | 60 | 63.4 |
Reaction time (min) | X3 | 46 | 60 | 80 | 100 | 114 |