3.3 Effect of temperature
C4 alkylation is an exothermic reaction. The low temperature is beneficial to the formation of C8 key components with higher RON40,41. Thus, the effect of reaction temperature on C4 alkylation from 281.2 K to 269.2 K with ChCl-Pho (1:2) additive was listed in Table 1. The difference of alkylate components between DESs-aiding systems and pure H2SO4 system as a function of temperature are shown in Figure 4. For the system with 1.0 wt% ChCl-Pho (1:2), it is clear that the targeted C8 components and the RON increase obviously from 83.77% at 281.2 K to 86.07% at 274.2 K, 97.39 at 281.2 K to 98.27 at 274.2 K, respectively, which is mainly attributed to lower reaction temperature. This tendency is in good agreement with our previous work, in which, lower temperature leads to a great increase in C8 contents and significant decrease in LEs, HEs and DMHs components15. However, in ChCl-Pho (1:2)-aiding system, when the temperature is below 274.2 K, the quality of alkylate is not improved as expected. The C8 contents dramatically decrease and HEs sharply increase at the 269.2 K. The C8 key components and the RON decrease obviously, and the content of C9+ components dramatically increase.
Table 1. Temperature-dependent alkylate components for H2SO4 alkylation with ChCl-Pho (1:2) as additive.