Studies On Desulfurizatioon For Straight-Run Diesel By Catalytic Oxidation With NO_x And Air

Sulfur oxides produced from combustion of diesel of sulfur containing is one of the most objectionable contamination of atmosphere. Many countries promulgated rules to limit the sulfur content of diesel stringently, usually in the range of 150 ug/g to 300 ug/g, even will be lower in the future. So it is of great urgency for refining industries to develop and produce cleaning fuel sufficed the environmental demands.Although hydrodesulfurization (HDS) processes have dominated desulfurization of liquid fuels in the past, their high cost and investment capacity as well as rigor react conditions have put refiners great pressure. So studies on none-hydrogen-reducing desulfurization methods were progressed impetuously, among which, the oxidation desulfurization process became a focus in recent years at home and abroad because of its advantages of milder operation conditions of normal temperature and pressure, without hydrogen consumption , safe and no pollution, lower investment and operation cost as well as selection oxidation for thioether, thiophene sulfur containing compounds in the diesel, which is its feature. Whereas, one hand, there were still such problems as using hydrogen' peroxide acid as oxidant which is expensive and can not be regenerated, and discharging of waste water of sulfur containing. On the other hand, if could use NOx as desulfurization oxidant for diesel, which pollutes the air severely exhausted from the nitric acid production, but it has excellent catalytic oxidation properties on the contrary, salvaging and lowing operating expenses of sulfur removing , I think, would both be realized.In view of these, a new desulfurization route for straight-run diesel through catalytic oxidation with nitrogen oxides (NOx) and air (NODS) was studied exploratoryly in this paper. In this method, the diesel feed was refined through extraction with a solvent and adsorption on solid following by catalytic oxidation with NOx and air as catalyst and oxidant instead of hydroperoxide in which the sulfides in the oil were converted to polysulfur oxides at ambient temperature and pressure. A lot of work has been done, for example, having selected the kind of catalyst promoter and extract agent, having studied about operating parameters for NODS including both the amount and the regeneration way of catalyst, catalyst promoter, extract agent and adsorbent, react temperature and time, phase separation temperature and time; having measured the oil yield under the optimum operating conditions selected and having examined the adaptability of NODS method for straight-run diesel with different sulfur content; having analyzed the quality of treated oil; having proposed the schedule drawing of NODS process.The results of experiments suggested that the catalyst promoter and the extract agent selected both satisfied the demands of desulfurization for straight-run diesel; the new desulfurization technology had many advantages, for instance, the oxidant was cheap and easy for regeneration, the oxidized sulfides had a reasonable way out. What's more, the treated oil having sulfur content lower than 95ug/g and oil yield about 93.7 percent, other qualities all met the standard of international clean diesel fuel.