Oxidation of Benzothiophenes Using Tert-amyl Hydroperoxide

Homogeneous oxidation using an oil-soluble oxidant, tert-amyl hydroperoxide （TAHP）, for ultra-deep desulfurization was performed under mild conditions in the presence of molybdenum oxide catalysts. Dibenzothio- phene （DBT）, benzothiophene （BT） and 4, 6-dimethyl-dibenzothiophene （DMDBT）, which are the refractory sulfur compounds for hydrodesulfurization （HDS）, were employed as model substrates for a simulated diesel fuel. Activity of molybdenum oxide supported on a macroporous weak acidic resin was investigated. The mass conversion of DBT reached near 100% at 90℃ and a TAHP/DBT molar ratio of 3 with 1% of molybdenum oxide supported on Amberlite IRC-748 resin for 1 h. It was further found that the activities of the model substrates decreased in the or- der of DMDBT 〉DBT 〉BT. In the flow oxidation using TAHP as the oxidant, mass conversion of DBT increased remarkably from 61.3% to 98.5% when dropping the weight hourly space velocity （WHSV） from 40 h^-1 to 10 h^-1. A series of experiments dealt with selectivity of this oxidation using TAHP revealed that the model unsaturated compounds, i.e. 4, 6, 8-trimethyl-2-nonylene, and 2-methylnaphthalene did not affect the oxidation of DBT. Carbazole had nearly no effect on the conversion of DBT using TAHP, but had some influence on the one using tert-butyl hydroperoxide （TBHP）. The mass conversion of DBT decreased remarkably from 75.2% to 3.6% when the content of carbazole increased from 0 to 500μg·g^-1. In the flow oxidation using TAHP as the oxidant, the concentration of DBT in model fuels was reduced from 500 μg·g^-1 to 7.2 μg·g^-1 at WHSV of 10 h^-1, and then reduced to 3.8 μg·g^-1 by adsorntion of Al2O3.

Homogeneous oxidation using an oil-soluble oxidant,tert-amyl hydroperoxide(TAHP),for ultra-deep desulfurization was performed under mild conditions in the presence of molybdenum oxide catalysts.Dibenzothio-phene(DBT),benzothiophene(BT) and 4,6-dimethyl-dibenzothiophene(DMDBT),which are the refractory sulfur compounds for hydrodesulfurization(HDS),were employed as model substrates for a simulated diesel fuel.Activity of molybdenum oxide supported on a macroporous weak acidic resin was investigated.The mass conversion of DBT reached near 100% at 90°C and a TAHP/DBT molar ratio of 3 with 1% of molybdenum oxide supported on Amberlite IRC-748 resin for 1 h.It was further found that the activities of the model substrates decreased in the or-der of DMDBT>DBT>BT.In the flow oxidation using TAHP as the oxidant,mass conversion of DBT increased remarkably from 61.3% to 98.5% when dropping the weight hourly space velocity(WHSV) from 40 h-1 to 10 h-1.A series of experiments dealt with selectivity of this oxidation using TAHP revealed that the model unsaturated compounds,i.e.4,6,8-trimethyl-2-nonylene,and 2-methylnaphthalene did not affect the oxidation of DBT.Car-bazole had nearly no effect on the conversion of DBT using TAHP,but had some influence on the one using tert-butyl hydroperoxide(TBHP).The mass conversion of DBT decreased remarkably from 75.2% to 3.6% when the content of carbazole increased from 0 to 500 μg·g-1.In the flow oxidation using TAHP as the oxidant,the concentration of DBT in model fuels was reduced from 500 μg·g-1 to 7.2 μg·g-1 at WHSV of 10 h-1,and then reduced to 3.8 μg·g-1 by adsorption of Al2O3.