To measure the thermal stability of PILs-XSS, TG curves were recorded in
flowing dry N2. As shown in Figure 5, the initial weight
loss at 293.4 °C was 8.9%, which was due to the adsorption of organic
solvents and water on the surface of the catalyst PILs-XSS during
washing. A complete loss of all covalently attached organic structures
was observed in the temperature range of 293.4–481.3 °C [33], and
the final amount of remaining organic components was approximately
12.9% of the total solid catalyst. Therefore, PILs-XSS is thermally
stable below 293.4 °C, proving the feasibility of this catalyst as a
solid catalyst basis for catalyzing CO2 to DMC by
one-pot method.
Fig. 5 TG analysis of PILs-XSS
3.2 The synthesis of DMC by one-pot method
3.2.1 Hydrocarbon spectrum analysis products
To detect the presence of dimethyl carbonate in the product, we
performed nuclear magnetic resonance on the product after the reaction.
Fig. 6 ( A ) was the 1HNMR spectrum, Fig. 6 ( B ) was the 13CNMR
spectrum, and Fig. 6 ( C ) was the marker of the carbon vibration peak
of each substance in the carbon spectrum. Combined with gas
chromatography and nuclear magnetic resonance spectroscopy, all
substances in the reaction were analyzed.