4. Conclusions
The effect of several DESs on the quality of alkylate and the
acid/hydrocarbons interfacial properties were investigated via
experiments and MD simulations. It is found that the introduction of
DESs almost has no impact on the reaction time. ChCl-Pho (1:2) displays
the most outstanding catalytic performance with RON up to 97.37 and the
C8 selectivity up to 83.64%. The most suitable addition
ratio for ChCl-Pho (1:2) and ChCl-TsOH (1:1) to
H2SO4 is about 1.0 wt% with the
improvement of C8 contents from 74.50 wt% in pure
H2SO4 system at 281.2 K to 83.64 wt%
and 80.71 wt% as well as the increase in RON from 95.80 to 97.37 and
96.93, respectively. However, the excessive addition of DESs leads to
the decrease in reaction enhancement, which is attributed to reduction
of the H2SO4 acidity. ChCl-Pho (1:2) and
ChCl-TsOH (1:1) have a little influence on 2,3,4-TMPs and DMHs,
including 2,5-DMH, 2,4-DMH, and 2,3-DMH with lower RON. However, both of
them have a great effect on the conversion of LEs and HEs to TMPs. With
the addition of ChCl-Pho (1:2), the targeted C8components 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 contributed to low reaction temperature. The addition of
ChCl-Pho (1:2) and ChCl-TsOH (1:1) show the effective catalytic
performance, but both of them can
not improve the catalytic lifetime of
H2SO4 catalyst.
From MD simulations, the phenyl molecules, such as Pho, TsOH, and BOA
molecules, is found to aggregate close to the interface with a higher
density peak in the interfacial regions, which plays the essentially
important role in the tunability of acid/hydrocarbons interface. The
addition of DESs can significantly increase the interfacial thickness,
promote the solubility and diffusion of isobutane with respect to butene
in comparison to the pure H2SO4 system,
thus making positively contributions to the quality of alkylate.