PILs-XSS : 1,2-dibromoethane ; PILs-XST : 1,3-dibromopropane ; PILs-XSO
: 1,4-dibromobutane ; PILs-XSP : 1,5-dibromopentane ; PILs-XSQ :
1,6-dibromohexane ;
Reaction conditions : catalyst PILs dosage2.5wt %,
CO2pressure1.5MPa, reaction temperature100 °C, reaction
time4h, methanol / PO molar ratio3 : 1, transesterification catalyst
Na2CO3dosage 3wt %.
The activities of a series of
PILs/Na2CO3 catalysts are compared in
Table 2. By comparing the catalytic activities of the same series of
bromides, it was found that the chain was longer, the catalytic activity
was lower. In the process of producing catalysts, it was found that the
chain was longer, the hardness of the synthesized spherical particles
was lower. Therefore, 1,2 - dibromoethane was reasonable as a raw
material.
3.4 Investigation of reusability
In addition to the high requirements for the catalytic activity of
organic catalysts, sustainable utilization is equally important in
production, which determines whether continuous production can be
achieved. Therefore, the reusability of PILs-XSS was evaluated under the
optimal conditions ( PILs-XSS dosage 2.5wt %, CO2pressure 1.5MPa, reaction temperature 100 °C, reaction time 4h, methanol
/ PO molar ratio 3: 1, Na2CO3 dosage 3wt
% ). As shown in Fig. 8, The catalytic activity of PILs-XSS was not
significantly decreased after five consecutive cycles. The spherical
state of the catalyst did not also changed. This indicated that the
catalyst had a strong mechanical strength and recyclability.