Study Of Dihydro-cyanopyridine Synthesis And Calculation Of Sodium Improved Flue Gas Desulfurization By Aspen Plus

Two main parts are included in this thesis.(1) Studies on synthesis of dihydro-cyanopyridine.3-cyanopyridine is mainly synthesized by the method of pyridine ammoxidation. The price of the raw material and catalyst is all very high. And toxic by-products like hydrocyanic acid are produced during the process. These makes the process might be not too economic on commenicial run. Dihydro-cyanopyridine can be also synthesized from 2-methylene-pentanedinitrile, which is a kind of acrylonitrile dimer.3-cyanopyridine can be proceduced from dehydrogenation of dihydro-cyanopyridine. This method may be an economical one and operated easily on large scale. In this thesis, the mechanism of cyclization of the acrylonitrile dimer was proposed reasonably, and then the selected kind of ionic liquid was synthesized and used as the solvent and catalyst of cyclization of acrylonitrile dimer. The results show that:Under the optimum synthesis conditions of 3-bromo-3-cyanopyridine being the molar ratio of SnCl4 to bromothalonil 0.60, reaction temperature 125℃and reaction time 7.0h, the conversion of taking off one brominated hydrogen molecule from bromothalonil was 7.96%. Under the optimum synthesis conditions of dihydro-cyanopyridine being the molar ratio of SnCl4 to 2-chloromethylenepentanedinitrile 0.70, reaction temperature 150℃and reaction time 6.Oh, the conversion of taking off one chloride hydrogen molecule from 2-chloro-methylenepentanedinitrile was 18.66%. And the reaction mechanism of taking off one hydrogenhalide molecule was proposed.Ionic liquids of [bmim][AlCl4] and [bmim]BF4 were prepared and applied to the cyclization reaction of 2-methylenepentanedinitrile. Product of dihydro-cyanopyridine was only found in the ionic liquid of [bmim][AlCl4] used as the catalyst, and analyzed by the 1HNMR. The cyclization conversion of 2-methylenepentanedinitrile was 21.66%. The mechanism of dihydro-cyanopyridine synthesis was proposed.(2) Studies on simulation calculating of improved Flue Gas Desulfurization by the method of the circulating sodium solution.A kind of Improved Flue Gas Desulfurization by the method of the circulating sodium solution was calculated by Aspen Plus Software. The results showed that the active concentration, lean solution temperature, pH value, and steam consumption were well consistent with the experimental data. The maximum relative deviation error was 10%. Under the conditions of the active concentration 17%-20%, the lean absorption solution temperature 30℃-50℃, the pH value was 4.5-5.0 and the flow ratio of liquid to vapor (L/V) 35-40, the steam consumption was about 15kg/kgSO2, and the desulphurization ratio of fresh solutions might attain above 95%. The recycled absorption solution was repeatedly used for five times, the desulphurization ratio was all above 80%, the SO2 concentration for the recycled aborption solution in an packed desorption column was in a range of 400-1000mg/L, and the sulfate ion concentration of recycled absorption-desorption solution was below 0.20mol/L. It is concluded that the method of the improved Flue Gas Desulfurization with the circulating sodium solution has a high absorption-desorption capacity and strong absorbent stability. It provided a basic foundation for the further pilot test and commercial run.