Study and evaluation of petroleum product stability on oxygen absorption (III) - effect of temperature and oxygen pressure on diesel fuel stability on oxygen absorption

Based on the study and evaluation of diesel fuel stabilities on oxygen absorption, the effect of temperature and oxygen pressure on oxygen absorption properties of Daqing straight run diesel fuel (SRDF) and hydrogenated coking diesel fuel (HCDF) was studied at 290 - 360 K under 0.10 - 0.25 MPa(O2) and Cu catalysis in darkness. The experimental result shows that the oxygen absorption quantities (OAQs) of two diesel fuels increase rapidly with the increasing of temperature or oxygen pressure at given times and oxygen pressure or temperature during oxygen absorption. The higher the oxygen pressure or the temperature and the longer the time, the greater the OAQs of diesel fuels. The OAQs change a little at shorter times, while they vary greatly at longer times. Low temperature has a great effect on OAQs of SRDF and high temperature affects clearly OAQs of HCDF. Oxygen pressure gives a evident action on OAQs of SRDF, but it affects a little OAQs of HCDF. At low temperature or high oxygen pressure the OAQs of HCDF is less than that of SRDF, while at high temperature or low oxygen pressure the OAQs of HCDF greater than that of SRDF. The more the types of unstable constituents, such as unsaturated hydrocarbons, especially conjugated dienes, cyclophane and so on and the higher the unstable constituent contents in diesel fuel, the easier the oxygen absorption reaction takes place and the more obviously the diesel fuel stability or quality decreases.