Abstract: In order to investigate the thermal oxidative stability of RP-3 jet fuel and coal direct liquefaction jet fuel, we used the color, acid number and solid deposits as comparison indexes for both jet fuels. The differences between the two jet fuels in thermal oxidative process then were analyzed by UV-Vis absorption and fluorescence spectroscopy. The coal direct liquefaction jet fuel shows a better thermal oxidation performance than RP-3 jet fuel in color, acid number and solid deposits. The spectra demonstrate that the thermal oxidative reaction in coal direct liquefaction jet fuel occurs continuously as the temperature increases from 160-300 ℃, and the oxidative products begin to form resin and asphltene at 200 ℃, while the thermal oxidative reactions in RP-3 already occurs to the stage of resin and asphaltene formation below 200 ℃.It is proved that the coal direct liquefaction jet fuel possesses excellent thermal oxidative stability.

Key words: coal, direct liquefaction, jet fuel, thermal oxidation stability, spectrum