As emerging green solvents, ionic liquids (ILs) have promising applications in many fields. However, its long reaction time and high price restrict its industrial application. The main reason for this is due to the generation of droplets during the synthesis reaction. Aiming at the process intensification of the 1-methylimidazole (MIM)-based ILs, this paper has studied the evolution behavior of the droplets during its synthesis according to droplet breakage theory. The results show that the droplet size distribution (DSD) and its number density are closely related to the reaction progress. By comparing the Kolmogoroff microscale and droplet size, the synthesis process can be divided into Reaction stage I, when the conversion of MIM is below 60%, and Reaction stage II, when the conversion of MIM is beyond 60%. High stirring speed and temperature increase have been put forward for each stage. The reaction time can be effectively reduced by 43.93%, which is instructive in improving the production efficiency of [BMIM]Br.
Yuxin Wu,Yuncheng Ding,Jianhong Xu,Yundong Wang,Kathryn Mumford,Geoffrey W. Stevens,Weiyang Fei
Utilization of carbon dioxide (CO 2 ) is of great significance in the development of CO 2 absorption and the solution of greenhouse gas effect. Highly efficient conversion of CO 2 into cyclic carbonate with green catalysts is essential for the more sustainable expansion of CO 2 fixation. Traditional batch reactor is limited by low efficiency, high cost and low security. Meanwhile, continuous flow system showcased a myriad of virtues, including shortening the residence time from hours to seconds, and decreasing reaction temperature, and possessing the nature of easy industrial scale-up. In this paper, a continuous-flow microreaction system was developed to synthesis propylene carbonate (PC) from propylene oxide (PO) and CO 2 using 1-butyl-3-methylimidazolium bromide ([BMIM]Br) as catalyst. By observing the flow patterns inside microreaction system, the effects of reaction temperature, molar fraction of catalyst, operating pressure, residence time, molar ratio of CO 2 /PO as well as recycling performance of catalyst on the overall performances were comprehensively evaluated into details. Under different reaction conditions, the flow patterns were set to vary between slug flow and annular flow. The results showed that the yield of propylene carbonate (PC) can reach 99.7% at 140 °C and 3.0 MPa with the residence time of 166 s, while the recycling performance of the designed system greatly conforms the future trend of green chemistry.
Wenjuan Zhang,Lei Shi,Dongfang Niu,Heng Xu,Xinsheng Zhang,Shuozhen Hu
The effect of methoxypolyethylene glycol (mPEG) on chromium electrodeposition from a mixture of 1- butyl-3-methylimidazolium-bromide ([BMIM]Br) ionic liquid and water is studied. The addition of mPEG does not affect the two-step reduction process of Cr(III). With the presence of mPEG in the electrolyte, the diffusion coefficient decreases dramatically, and the resistance of the electrolyte and charge transfer increase, resulting in a reduced deposition rate and a smooth and crack-free coating surface. The hydrogen evolution reaction is suppressed, and more metallic Cr is deposited in the coating layer. Considering both the surface morphology and corrosion resistance, 80 mmol L -1 mPEG is the optimum concentration for smooth and pinhole-free chromium electrodeposition in the mixture of [BMIM]Br ionic liquid and water.
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