Functionalized Acidic Ionic Liquid Catalytic N-alkanes Isomerization Performance Study

The standards of fuel quality have tended to the direction of low content of aromatics and alkenes due to the increase of consciousness for environmental protection. The products of long carbon chain alkaries in the distillate oil obtained in petroleum refining may be conversed into isoalkanes in the isomerization. As the n-decane and other long-chain alkanes have a strong trend of cracking reaction in isomerization at the same time. So the study for environment-friendly catalyst will be the key to improve isomerization selectivity of the long carbon chain alkanes.In this thesis, triethylamine hydrochlorine-aluminium hloride ionic liquids (Et3NHCl-AlCl3), 1-butyl-3-methylimidazolium chlorid chlorine-aluminate ionic liquids ([C4mim]Cl-AlCl3), pyridinium chlorid chlorine-aluminate ionic liquids ([Py-H Cl]-AlCl3) were prepared, and the Et3NHCl-AlCl3(x=0.67) had been modified by adding metal chlorides and HCl. The forms of anion in ionic liquids modified by adding HCl were characterized by 27AlNMR; the acidity of ionic liquids were characterized by means of FT-IR technique using pyridine and acetonitrile as molecular probe and UV-vis spectroscopy. The isomerizaiton of n-decane was catalyzed by Et3NHCl-AlCl3; meanwhile, the process conditions were optimized. The influence of the different cation structure of the above chlorine aluminate ionic liquids and the modified method of Et3NHCl-AlCl3 ionic liquid on the catalytic performance was studied.The acidity of chlorine-aluminate acidic ionic liquids was determined by means of FT-IR technique using pyridine and acetonitrile as molecular probe and UV-vis spectroscopy.The results showed that the acidity of ionic liquids was determined by the content of anhydrous aluminum trichloride. The acidity of ionic liquids increases with the molar fraction of AlCl3 increasing.Taking Et3NHCl-AlCl3 as catalyst, the acidity of the ionic liquids, the mole ratio of ILs to n-decane, the reaction temperature,the reaction time and other factors on the results of isomerization of n-decane were studied, the optimum reaction condition was obtained: the molar fraction of AlCl3 is 0.67, the mole ratio of ILs to n-decane is 1:4, reaction temperature is 45℃and reaction time is 8 h; Under the optimum reaction conditions,35.6% conversion of n-decane,17.0% isomerization selectivity,96.1% isomerization ratio were obtained. Then the isomerization of different carbon chain alkanes catalyzed by [Cnmim]X-AlCl3. [Py-HCl]-AlCl3 and Et3NHCl-AlCl3 three ionic liquids with different carbon structures, the catalytic reactivity and isomerization selectivity catalyzed by the Et3NHCl-AlCl3 ionic liquids were higher.The acidity of Et3NHCl-AlCl3 ionic liquid was adjusted in some degree by adding metal chlorides and HCl. The results showed that the acidic strength of Et3NHCl-AlCl3 (x=0.67) ionic liquids modified by ZnCl2 became weaker, the catalytic activity of ionic liquids in the isomerization of n-decane decreased, but the isomerization selectivity was improved in certain some degree, and the yield of liquids increased. The acid strength of Et3NHCl-AlCl3 (x=0.67) ionic liquids modified by HCl increased, which improved the catalytic activity in the isomerization of n-decane and the content of dimethyloctane in the isodecane. The conversion of n-decane increased from 36.5% to 46.1% and the content of dimethyloctane increased from31.7% to 34.1%.