The Molybdenum-based Functional Compounds: Synthesis And Application In Cleaning Oil Production

The production of cleaner oil products was the inevitable trend in petroleum industry.On the basis of our team's accumulated experience about synthesis and application of scattered elements ionic liquid functional compounds,and in combination of research progress of cleaning oil products with the advantages of molybdenum compounds,two aspects were studied:the catalysts of oxidative desulfurization of fuels and green oil additives without sulfur and phosphorus.A series of molybdenum-based functional compounds were designed and synthesized.The application of those compounds in the above two aspects were also studied in detailEighteen molybdenum-based functional compounds were synthesized,including ten octamolybdates(four imidazolium-based octamolybdates,three new quinolinium-based octamolybdates and three new piperidinium-based octamolybdates),four peroxomolybdates and four molybdenum or tungsten-based ionic liquids.The structure of these compounds were characterized by mass spectrometry(ESI-MS),infrared(FT-IR)and nuclear magnetic resonance(NMR)and elemental analysisTen octamolybdates were applied to remove dibenzothiophene(DBT)in a model diesel,which showed high catalytic activity towards the oxidation of DBT.The removal rates of sulfur of octamolybdates reached above 98%in ionic liquids extraction coupled with catalytic oxidation desulfurization system.It was showed that the removal rate of sulfur increased first and then decreased with the growth of the carbon chain of the cation.The highest removal rate of sulfur was obtained when the number of carbons in the chain of cations was twelve The catalytic oxidation reactivity of three octamolybdates which have the same number of carbons in the chain of cations decreased in the order:[C12mim]4Mo8O26>[C12qui]4Mo8O26>[C1,12pip]4Mo8O26.The optimal reaction conditions using[C12mim]4Mo8O26,[C12qui]4Mo8O26 and[C1,12pip]4MO8O26 catalysts respectively were determined based on the studies of the effects of temperature,time,the amount of the catalyst,H2O2/Sulfur molar ratio and the volume ratio of[C8mim]BF4 and model diesel on desulfurization.The systems were also applied to commercial gasoline,and satisfactory results were obtained.The reaction mechanism was also studied preliminarily by FT-IR and HR-MS:the oxidation product of DBT was dibenzothiophene sulfone(DBTO2),and the reactive intermediate of octamolybdate was probably pero-monomolybdenum.Four peroxomolybdates were used as catalysts to remove DBT in a model diesel in ionic liquids extraction coupled with catalytic oxidation desulfurization system.It was shown that the removal rate of sulfur was in the following order:[C16mim]2Mo2O11>[C1,16pip]2Mo2O11?[C1,16pyr]2MO2O11>[C16qui]2Mo2O11.The optimal reaction conditions using[C16mim]2Mo2O11 and[C1,16pip]2Mo2O11 as catalysts respectively were determined based on the studies of the effects of temperature,time,the amount of the catalyst,H2O2/Sulfur molar ratio and the volume ratio of[C8mim]PF6 and model diesel on desulfurization.The removal of DBT reached 98.9%under mild conditions(T=30?time=1h,n(H2O2):n(S)=4,V([C8mim]PF6):V(n-octane)=1:10,the concentration of[C16mim]2Mo2O11=0.25 wt%).To our satisfaction,[C16mim]2Mo2O11 catalyst could be recycled ten times without obvious decrease in catalytic activity.The system was also applied to commercial gasoline and diesel oil,and the highest removal of sulfur reached 92.3%.The tribological performances of molybdenum or tungsten-based ionic liquids in lubricant base oil were studied.Oil solubility tests showed that the solubility of[N8,8,8,1]2MoO4 and[N8,8,8,1]2WO4 in 400SN base oil was superior to that of[C4,8im]2MoO4and[C4,8im]2WO4.The examination of two ionic liquids on a four-ball tester showed that the tribological performance of[N8,8,8,1]2MoO4 as additive in base oil 400SN was better than that of[N8,8,8,1]2WO4.Adding 0.5 wt%(mass concentration)[N8,8,8,1]2MoO4 in base oil 400SN improved the weld load(PD value)of base oil one lever,increased maximum non-seizure load(PB value)by 23.8%and shortened wear scar diameter(WSD)by 34.6%.Energy dispersive spectroscopy(EDS)analysis of tribofilm generated on the worn surface indicated that the improvement of tribological performance was probably due to tribo-chemically boundary films formed on the rubbing surface which were composed of MoOx or WOx and FeOx.According to the results of copper strip corrosion test,base oil 400SN with 0.5 wt%[N8,8,8,1]2MoO4 or 0.5 wt%[N8,8,8,1]2WO4 exibited almost no corrosive effect on copper strip.