Oxidative Desulfurization Of Dibenzothiophene Using Oil-soluble Oxidants

Along with the more and more strict demand on environment protection, there is a urgent need to produce low sulfur fuel oil to meet the future environmental legislation on the sulfur content. The oxidative desulfurization(ODS) is considered to be one of the new promising methods for super deep desulfurization. ODS has advantages of mild reaction condition, economy, and especially can remove dibenzothiophenes which are hard to remove in hydrodesulfurization(HDS). Currently, most of the oxidants, such as peroxyl acid and pertrifluoroacetic acid are water-soluble. These oxidants always make the oil emulsify again and the reactors are restricted in batch systems because there are two phases between oil and water-soluble oxidants.In this background, we use oil-soluble oxidants instead of water-soluble ones as oxidants. Theoxidation of model sulfur compound------dibenzothiophene(DBT) in decalin is performed toinvestigate the oxidative desulfurization by using t-amyl hydroperoxide (TAHP) and Cyclohexanone peroxide (CYHPO).In the aspect of TAHP synthesis, through investigating the effects of sequence of reactants, reaction temperature, reaction time, reactants mole ratio and concentration of alkali on TAHP synthesis and purification we get the optimal reaction condition. The birth rate of TAHP is improved from 38% to 68%, and the reaction time is shortened from 24h to 2h. The structure of TAHP is affirmed by IR spectrum. Effective content of TAHP is up to 95% by iodometry.The oxidation of DBT in decalin solvent is conducted using oil-soluble TAHP. The effects of oxidant amount, reaction temperature, reaction time and catalyst are investigated in detail. we get the optimal oxidative condition by orthogonal experiments and single factor experiments. The desulfurization rate is up to 97%. The recovery ratio of model oil is up to 99%. The catalyst is necessary to oxidize DBT with TAHP. Weak acid cationic exchange resin of D113 large aperture acrylic acid series supported MoO₃ catalyst has relatively high activities. After using the catalyst for 10 times, it still has a good activity.The oxidation of DBT in decalin is conducted using oil-soluble oxidant CYHPO. The effects of oxidant amount, reaction temperature, reaction time are investigated in detail. The results show that under optimal conditions the desulfurization rate is up to 91% and catalyst is not needed. The little water is removed by molecular sieve adsorption. The recovery ratio of model oil is up to 98% after the treatment with centrifugation and adsorption.