The Oxidation Removal Of Benzothiophene And Dimethyl Disulfide

Facing the increasing strict sulfur content standard of liquid fuels,many countries have explored all kinds of desulphurization techniques.The traditional hydrodesulphurization (HDS) process becomes economically insufficient.Oxidative desulphurization(ODS) becomes the hotspot which is investigated extensively due to its mild reaction condition, simple equipment and high efficiency.Oxidative-adsorption desulphurization is more available because the loss of fuels and the influence of fuels quality can be avoided. Compared with oxidative-extraction desulphurization,oxidative-adsorption desulphurization uses solid adsorbent as a substitute of solvent.In this paper,titanium containing molecular sieves and H₂O₂ were used as catalysts and oxidant,respectively.Silica gel and Al₂O₃ were chosen as adsorbents for the oxidative-adsorption desulphurization of benzothiophene in model fuel.The choice and dosages of adsorbent,molar ratios of H₂O₂ and sulfide as well as reaction temperatures were investigated.In addition,reuses of the catalyst and adsorbent and the desulphurization for the diesel oil were also researched.The results showed that the preferable conditions were as follows:Ti-HMS and A-silica were chosen as catalyst and adsorbent separately;the mass ratio of catalyst and model fuel was 1:700;the mass ratio of adsorbent and model fuel was 1: 7;the molar ratio of H₂O₂ and sulfide was 4:1;the reaction temperature was 60℃.The sulfide was oxidized to sulphone,which was adsorbed by adsorbent immediately.The oxidation and adsorption occurred as a simultaneous process.The desulphurization of diesel was researched under the same conditions of desulphurization of model fuel.The removal of sulfide reached as high as 91%.The dosage of catalyst was less and the adsorption capacity of adsorbent was larger.The mass ratio of catalyst and diesel was 1:168.Per gram of adsorbent could adsorb about 5 mg sulfur.In addition,using Ti-Si molecular sieve as catalyst,hydrogen peroxide as oxidant,solid adsorbent or solvent were introduced to remove the oxidation products to realize the desulphurization of dimethyl disulfide in model fuel.The choice and dosages of catalysts, adsorbents,molar ratios of H₂O₂ and sulfide,reaction temperatures were investigated.The results showed that oxidative-adsorption and oxidative-extraction both obtained high removal rates of dimethyl disulfide.Sulfide was oxidized to the high polar oxidation product,which was adsorbed by adsorbent or extracted by solvent immediately.The desulphurization rate of model liquefied petroleum gas was as high as 92.98%.