Structural characterization and analysis of existent gum in coal-based aviation kerosene base oil

Using coal-based aviation kerosene base oil as raw material, the existent gum was extracted. The composition and structure of the gum were characterized by elemental analysis, GPC, XPS and FTIR. The occurrence forms and relative contents of elements in the gum was systematically studied. The factors promoting the formation and aggregation of the gum were discussed. The results show that the gum molecules tend to be acidic as a whole, with more aromatic rings and other unsaturated functional groups. The heteroatoms are mainly O and N, and the content is more than 20%. The existing forms of O are hydroxyl or ether bond (C-O), carbonyl (C̿┴ O), carboxyl (COO-) and adsorbed oxygen. The existing forms of N are pyridine nitrogen, pyrrole nitrogen, nitrogen oxides and amines. Carboxylic acids and heterocyclic nitrogen compounds participate in the reaction of forming gum. The carboxyl and hydroxyl groups combine with pyrrole nitrogen and pyridine nitrogen to form hydrogen bonds, which promote the formation and aggregation of the gum. In addition, olefin groups are also important factors in promoting the formation of the gum. Compared with petroleum gum and coal tar gum, the proportion of unsaturated structures in coal-based aviation kerosene base oil colloids is larger. In the deep processing of fuel oils products, such gums are easily removed by hydrodeoxygenation, hydrodenitrogenation, and olefin hydrogenation and saturation. © 2020, Chemical Industry Press Co., Ltd. All right reserved.