Synthesis Of Hyperbranched Polymeric Ammoniums And Its Application In Extraction Of Benzene/Cyclohexane

Separation of benzene/cyclohexane mixtures is industrially significant.Cyclohexane is produced by the addition of hydrogen to benzene under a Ni or Pt-catalyst.Consequently,the removal of the unreacted benzene from the reaction solution is very important.Because benzene and cyclohexane have the close-boiling points,separation of benzene/cyclohrxane mixtures by traditional distillation is very difficult.Presently,instead of normal distillation,azeotropic or extractive distillation is practiced for separation of benzene/cyclohexane mixture.In order to solve the problem,the researchers studied liquid-liquid extraction process.In this work,the complex solvent system,Hyperbranched polymers ammoniums dissolved in DMSO,is found to be a good extractant for the separation of benzene and cyclohexane.Therefore,we prepared PAMAM-PCA,PAMAM-NO₃,PAMAM-TFA and PVBC-TMA.Then the quaternary ammonium dendrimer structures were extensively characterized with ¹H NMR,FT-IR and TGA.Finally,we found that the hyperbranched polymers ammonium can be dissolved in DMSO.In this work,a new solvent extraction system of extracting benzene and cyclohexane was been investigated.We measured the equilibrium data of the ternary system?cyclohexane+benzene+dimethyl sulfoxide?and the quaternary system{cyclohexane+benzene+?dimethyl sulfoxide+hyperbranched polymers ammonium?}at different temperatures.Here,the hyperbranched polymers ammoniumsrefertoPAMAM-PCA,PAMAM-NO₃,PAMAM-TFAand PVBC-TMA.In order to evaluate the extracted performance of composite solvent,we calculate the selectivity coefficient of the solvent and distribution coefficient of the solute.The experimental data show that,as the mass fraction of the hyperbranched polymers ammoniums in the co-solvent becomes larger,and the selectivity coefficient becomes larger.Meanwhile,when the temperature increased,the selectivity coefficient of the solvent would be declined slightly.PVBC-TMA compared with PAMAM-PCA,PAMAM-NO₃,PAMAM-TFA,the selectivity coefficient larger.We focused on the system of{cyclohexane+benzene+?DMSO+PAMAM-PCA?},the selectivity coefficient of the ternary solvent system is6.064¹9.920,and the distribution coefficient is 0.101⁰.536 at 25°C,the selectivity coefficient of the ternary solvent system is 5.895¹9.349,and the distribution coefficient is 0.132⁰.544 at 30°C.The series of PAMAM ammonium salt show nearly in separation effect,bnt the PVBC-TMA hyperbranched ammonium shows better separation effect.