Photochemical oxidation of thiophene in n-octane/water extraction system by using air as oxidant was studied.Results obtained here can be used as the reference of oxidative desulfurization of gasoline because thiophene is one of the main sulfur-containing components in fluid catalytic cracking gasoline.A 500 W high pressure Hg lamp （wave length 365 nm, 0.19 kW·m -2 ） was used as the light source for irradiation and air was introduced by a gas pump for supplying O2.Thiophene dissolved in n-octane was photodecomposed and removed into the water phase at ambient temperature and atmospheric pressure.Thiophene can be photo-oxidized directly to sulfone,sulfoxide, or ethanedioic acid,SO 2- 4 ,CO2.The photo-oxidation kinetics of thiophene with O2 was first-order with rate constant of 4.42×10 -5 s -1 and half-time of 4.36 h.The desulfurization yield of thiophene in n-octane was 58.9% for a 5 h photo-irradiation under the conditions with air flow at 150 ml·min -1 and water/oil ratio at 1∶1.The sulfur content could be reduced from 800 μl·L -1 to less than 330 μl·L -1 .
Thiophene(C4H4S) is a typical sulfur-containing compound in fluid catalytic cracking(FCC) gasoline.Oxidative desulfurization of C4H4S in n-heptane solution was conducted with hydrogen peroxide (H2O2) and formic acid over a catalyst of 5A molecular sieve loaded with ceria.The effects of oxidative agent, solvent,reaction temperature as well as the addition of phase transfer catalyst were investigated in detail.The reaction course of oxidative desulfurization of C4H4S was preliminarily studied.The oxidation of C4H4S was achieved under mild reaction conditions and it was easy to raise the reaction temperature or increase the reaction time to achieve high oxidation conversions.The results showed that the conversion of C4H4S in n-heptane solution was 78.2% under the condition of reaction temperature of 50℃,nH2O2∶nS=10∶1,VH2O2∶VHCOOH=1∶1.The conversion of C4H4S was 94.5% when an emulsifier OP was added to this system.However, with the addition of tetrabutylammonium bromide (TBAB), a bromine substitution product appeared in the oxidation of C4H4S.
