The Preparation And Performance Studies Of 1-(2-hydroxyethyl)-4-(2-hydroxypropyl) Piperazine

In this thesis, 1-(2-hydroxyethyl)-4-(2-hydroxypropyl) piperazine (HEHPP) of asymmetric structure was synthesized using 1-(2-hydroxyethyl) piperazine (HEP)and propylene oxide (PO) as raw materials. The feasibility of reaction was confirmed by calculating its reaction thermodynamic parameters. The synthesis conditions such as the molar ratio of HEP to PO, temperature and the reaction time were optimized. The product purity could be up to 98.16% when the molar ratio of HEP to PO was 1.0, reaction temperature of 50℃ and the reaction time of 180 min. Because of HEP for liquid under the normal temperature, with features of be reactants as well as solvent, so the synthetic process without adding other organic solvent and the product without solvent separation process.Structure of HEHPP was characterized by NMR and GC-MS, the results proved that the HEHPP has been successfully synthesized and impurities in product were produced from piperazine. The the freezing point of HEHPP was-48.6℃ and the boiling point was 192.0℃, which was confirmed by DSC characterization. The relative density of HEHPP was 1.05397 g cm -3 under 25 ℃, which measured by pycnometer. The pKa1 and pKa2 value of HEHPP’s conjugate acid were 3.73 and 7.98 respectively, using the method of potentiometric titration. The opening flash point and burning point of 159 and 163℃ respectively, which is measured by cleveland open cup method. HEHPP can in any proportion miscibility with water and ethanol under normal temperature but hardly soluble in benzene. The HEHPP/H2SO4 aqueous solution in PH value of 4.0～ 6.5 can hav an average corrosion rate on the stainless steel of model 304, in 1.626 mm every year.The absorption/desorption properties to SO2 of HEHPP solution was studied. Adding H2SO4 to solution of HEHPP, not only can reduce the volatilization loss of amine, but also can improve the first desorption rate of SO2. One mole of HEHPP can saturated absorb 0.452 mole of SO2 when the HEHPP concentration was 0.3 mol/L, pH value of 5.5, and absorption temperature of 50℃. The desorption rate of SO2 was 97.6% when the desorption temperature was 103℃, and desorption time of 150 min. HEHPP solution still had good absorption/desorption performance of SO2 after recycled for four times, the saturated absorption just fell by 1.3%, and the desorption rate increased by 4.9%. maneuverability. HEHPP had features such as nonvolatile, high stability, miscibility with water or ethanol in arbitrary proportion, low corrosion to equipment, and good desulfurization performance, so can be used as a new type of organic amine desulfurization agent.