Table 1: Coded and Decoded Levels of the Factors

Coded Levels	X1:TOS (min)	X2: GHSV-C2 (ml/g h)	X3: XC1	X4: Reaction Temperature (°C)
(−1)	20	810	0.4	520
(+1)	60	2240	0.8	580
(0)	40	1525	0.6	550