喷气燃料储存中生成的胶质化合物的研究

STUDY ON ADSORPTIVE GUM IN JET FUEL DURING STORAGE

用中性氧化铝吸附和无水乙酸脱附的方法制备了几种喷气燃料的吸附胶质(Adsorptive gum)。通过模拟加速储存试验考察了喷气燃料中生成的吸附胶质。采用色-质联用分析法(GC-MS)和红外光谱分析法(FT-IR)分析了吸附胶质的组成,并探讨了喷气燃料在储存过程中吸附胶质的变化规律。结果表明,变色喷气燃料中的颜色物质全部集中在吸附胶质中,吸附胶质的组成以烷基苯酚类(及其二聚物)和芳香酯类化合物为主。吸附胶质能有效地反映喷气燃料在储存过程中的变质情况,储存中吸附胶质和颜色增加显著,新生成的吸附胶质与储存前燃料中的吸附胶质无显著差别。吸附胶质的产生与喷气燃料在一定条件下的氧化和缩聚反应有关。吸附胶质可能是储存中所产生的不溶物的母体化合物。

The raw jet fuels were taken from refineries, field storage depots or made from simulative accelerated storage followed ASTM D4625 Stress or ASTM D2274 Stress methods. To prepare the adsorptive gum for this study, the raw jet fuel sample was led into a column packed with neutral alumina powder in 100-200 mesh size as the adsorbent, then desorbed the gum from the adsorbent with acetic acid and distilled water, and collected the adsorptive gum from the eluteriant. The adsorptive gum samples were analyzed with gas chromatography combined with mass spectrometry (GC-MS) and Fourier-transition infrared spectrometry (FT-IR). The results demonstrate that the dark materials, that was responsible for the colorization of jet fuels, were concentrated in adsorptive gum. The predominant ingredients in adsorptive gum were alkylated hydroxybenzene (some in polymerized state) and aryl ester. IR spectra results suggest that the adsorptive gum may be the major contributor to the formation of insoluble products. The amount of adsorptive gum in jet fuels increased substantially during storage, and the color of the jet fuels grew darker. The adsorptive gum formed during storage showed no evident difference in chemical structure comparing to the original adsorptive gum in jet fuels before storage. The reaction of oxidation and polymerization played an important role in producing adsorptive gum. The adsorptive gum in jet fuel may be the precursor of the insoluble products.