Symbols and definitions of the parameters.

Parameter	Explanation
T	Temperature
t	Time
i	Combination number
Ai	Catalyst combination number using charging method I in Table 1
Bi	Catalyst combination number using charging method II in Table 1
Y(T)	Ethanol conversion rate, corresponding to a specific catalyst combination and temperature (%)
P(T)	C4 olefins selectivity, corresponding to a specific catalyst combination and temperature (%)
y I	Yield of C4 olefins in charging method I
y II	Yield of C4 olefins in charging method II
x1	Co load
x2	Co/SiO2
x3	HAP
x4	Amount of ethanol added per minute