Process Optimization For The Synthesis Of 1-（2-aminoethyl）-2-Imidazolidone From Supercritical CO₂

1-（2-Aminoethyl）-2-imidazolidone（AEI）is an important raw material of fine chemicals.It’s a kind of 2-imidazolizone derivative with high economic value and widely used in pharmaceutical and material areas.In this paper,AEI was directly synthesized from ethylene diamine（A）,ethanolamine（B）and CO₂ with Ruthenium loaded on activated carbon（AC）as catalysts and water as solvent.This synthetic route can provide theoretical basis to the resourcization of CO₂ and industrial production of AEI.Ruthenium loaded on activated carbon has been used as catalyst in this paper.A series of catalysts were prepared and the effects of modify methods of supporter,promoters and preparation conditions on the catalystic activity of Ru/AC were studied.It is found that AC pre-treated by 20%HNO₃ has higher concertration of oxygenous acid groups on its surface than normal AC,that made it easier for RuCl₃ to contact with the surface of AC.Extra oxygenous acid groups on the surface of Ru/AC may affect the catalytic activity,alkali treatment after dipping can eliminate those groups on the catalyst and increase the catalytic activity of Ru/AC.Barium has been found to be a more effective promoter than Kalium.and the optimal catalyst dosage of Ruthenium was 1%.Results of thermodynamic analysis showed that reaction parallel with the second step reaction is the only side-reaction in the synthesis of AEI and the side-product is 1-（2-hydroxyethyl）-2-imidazolidinon（HEI）.The influence of solvent,reaction temperature,CO₂ pressure and reaction time on the ethylenediamine conversion and AEI yield were studied.It was showed that solvent is a factor which can affect the selectivity of this reaction and use H₂O as solvent can increase the selectivity of AEI.The order of main factors influencing on the yield of the target product was:reaction temperature>CO₂ pressure>reaction time.Synthetic process of AEI was optimized with the help of response surface method,under the appropriate conditions of reaction temperature=207℃,CO₂ pressure =9.4 MPa,reaction time =10.1 h,and the optimal yield of AEI was 83.1%,which is quite close to the predicted value of 84.9%.The kinetics of reaction was studied.The results showed that the activation energy of the first step is 14.99097 kJ/mol,and the pre-exponential factor of the first step is 20.395.The activation energy of the second step is 44.47522 kJ/mol,and the pre-exponential factor of the first step is 10829.184.Which means the second step is the rate-determining step of the whole reaction.