Synthesis Of Immobilized Ionic Liquids And Its Application In Preparing Carbonates

Carbonate is a kind of very important chemical raw materials and it plays a great role in the chemical industry. For the preparation of carbonate, catalyst in which served as a very important role, however, at present, most of the catalyst widespread poor activity, weak selectivity, difficult to separate and complex preparation process. Aiming at these problems, the activity of the catalyst was enhanced from two angles.One is to increase the number of the functional ions and the other is to strengthen the activity of the ions. And two efficient heterogeneous catalysts were prepared for epoxides and carbon dioxide to prepare cyclic carbonates without any additional co-catalysts and organic solvents. In addition, the further modification quaternary phosphonium salts catalyst was applied to the synthesis of dimethyl carbonate by transesterification reaction.To improve the catalyzer activity,1,4-Diazabicyclo[2.2.2]octane (DABCO) was adopted as the active group to improve the number of functional ions for its characteristics of bi-functional modification. A series of novel bis-ammonium ionic liquid immobilized polystyrene (BisAm-i-PS) heterogeneous catalysts were synthesized for the cycloaddition reaction of CO2 and epoxides. Under an optimal reaction condition, all the ammonium immobilized catalysts showed high selectivity (>99%). Bis-ammonium immobilized catalysts were more efficient than single-ammonium ones did. The yield was further increased by introducing the functional end groups. The effects of parameters, such as halide anions of the catalysts, reaction temperature, initial pressure and reaction time were also investigated with-CH2CH2OH ended BisAm-i-PS (BisAm-OH-i-PS) as the catalyst. In addition, the catalyst possessed good stability, and both catalytic activity and selectivity were always more than 99% for 5 times recycle tests.The three (2,4,6 trimethoxy phenyl) phosphate salts was adopted as the active component for the cycloaddition reaction of CO2 and epoxides. It possess a large space structure and a lot electron-donating groups that can weaken the binding effect of anion and to improve the catalyzer activity. The heterogeneous catalysts that contain different halide anions exhibited good selectivity for PC (>99.7%), which made a much better performance than traditional triphenyl phosphonium salt catalyst. And it was found that the propylene carbonate yield come to 99.6% under a relatively mild reaction conditions with the catalyst. Besides, the influence of reaction conditions, such as temperature, pressure, time and catalyst amount were also tested. At the same time, the catalyst behaved a good cycle performance that both the selectivity and yield of PC were more than 99% after 6 times recycles.The quaternary phosphonium salts catalyst was further alkalization modified to obtain alkaline solid base catalyst by methanol solution of potassium hydroxide for the synthesis of DMC according to transesterification. It exhibited excellent catalytic properties under a relatively mild reaction conditions the DMC yield and selectivity could come to 69.6% and 99.7%. Besides, the catalyst showed a nice recycle performance, after 4 times reused, the yield of target product DMC remained at a good level of 60.3% and the selectivity was still 99.6%.