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Batch reaction experiments were performed to investigate the salt effect on the yield of trioxane in the reaction solution. The salts considered include NaHSO 4 , Na 2 SO 4 , NaH 2 PO 4 , Na 2 HPO 4 , KCl, NaCl, LiCl, ZnCl 2 , MgCl 2 , and FeCl 3 . The effects of the anionic structure and the cation charge density on the yield of trioxane in the reaction solution were elucidated and the mechanisms that govern such effects were established. It is shown that the first four salts exerted a negative effect on the yield of trioxane in the reaction solution and such an effect increased progressively from left to right. This trend is due to the formation of NaHSO 4 , H 3 PO 4 , or (H 3 PO 4 and NaH 2 PO 4 ), which decreased the concentration of H + in the solution. The latter six salts showed a positive effect on the yield of trioxane in the reaction solution. The salt effect paralleled the ability of the salt to decrease the water activity of the reaction solution and followed the order KCl < NaCl < LiCl < ZnCl 2 < MgCl 2 < FeCl 3 . Continuous production experiments were performed to investigate the salt effect on the concentration of trioxane in the distillate. The salts considered were KCl, NaCl, LiCl, ZnCl 2 , MgCl 2 , and FeCl 3 , and the salt effect increased progressively from left to right. Such an effect was shown to be determined by the ability of the salt to increase the yield of trioxane in the reaction solution and to increase the relative volatilities of trioxane and water and of trioxane and oligomers.

Biodiesel is considered as one of the best resources to replace fossil fuels. There are a lot of mixtures of methanol and hexane in the process of biodiesel production. In this study, a green solvent ionic liquid extraction is used to separate methanol and n-hexane. The molecular dynamics method is used to study the extraction mechanism of methanol and n-hexane by ionic liquid. The extraction efficiency predicted by molecular dynamics simulation is compared with liquid–liquid extraction experimental values. The deviation between the experimental data and the simulation data is less than 8%, which shows that they have good consistency. The interaction energy, radial and spatial distribution functions, and self-diffusion coefficients are calculated based on the molecular dynamics simulation results. At the same time, anions play a vital role in the extraction process. A method for separating methanol and recovering ionic liquid using Aspen plus is proposed. The optimum operating parameters are determined. The recoveries of ionic liquid and methanol were 99.32% and 94.11%, respectively. The minimum total annual cost of the IL extraction process is 17.31% lower than that of traditional extraction process. At the same time, environmental analysis is performed. Global warming potential and eutrophic potential of the new process are 86.1% and 85% lower than those of the traditional process, respectively. The new process has good sustainable development advantages. This study provides theoretical guidance for the recycling and comprehensive utilization of methanol and n-hexane and provides a new method for the sustainable development of green chemicals.

Green, efficient, and low energy consumption capture of CO 2 from the flue gas of coal-fired power plants has been one of the most popular research topics in the world. In this work, a concept process of postcombustion capture (PCC) using a choline chloride/urea (1:2) deep eutectic solvent (DES) as a physical solvent was proposed. The DES-based PCC process is modeled and simulated using commercial Aspen Plus simulation software. The required parameters were studied and further embedded in Aspen Plus. The simulation results show that the process has a good capture effect; the capture ratio of CO 2 is 97.33%, and the purity of CO 2 in the product gas is 99.42%. Through sensitivity analysis, the influence of several key parameters on the process performance is studied and reasonable operating conditions are determined. Exergy analysis is carried out for a CO 2 absorption unit and a solvent regeneration unit. The results show that the total exergy efficiency of these two units is 74.28%. The new DES-based PCC process has great potential and will provide a new way to capture CO 2 in the flue gas of coal-fired power plants.

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