TS-1/过氧化氢催化体系中有机硫化物的选择氧化

Selective Oxidation of Organic Sulfur Compounds over TS-1/H_2O_2

研究了TS 1/过氧化氢催化体系中几种典型有机硫化物的选择氧化脱除 .结果表明 ,噻吩和 2 甲基噻吩仅在水或叔丁醇溶剂中才能被有效氧化脱除 ,且两者的反应历程不同 .噻吩分子中的硫原子先被氧化 ,2 甲基噻吩分子中的噻吩环先被氧化 .当过氧化氢与硫化物摩尔比为 4时 ,噻吩和 2 甲基噻吩均可被氧化为硫酸 .采用甲醇、乙腈和水作溶剂时 ,甲基硫醚和丁基硫醇均可被选择氧化脱除 .由于存在空间位阻 ,苯并噻吩、二苯并噻吩及 4 ,6 二甲基二苯并噻吩在TS 1/过氧化氢体系中均不能被有效脱除 .

The oxidative desulfurization, one of the most promising non-HDS processes, is very efficient in oxidizing thioethers, mercaptans and benzothiophenes over organic acid catalysts. However, thiophene and its alkyl derivatives cannot be oxidized under the conditions. In this work, we study the selective oxidation of organic sulfur compounds, especially thiophene and 2-methyl thiophene, over TS-1 by H 2O 2 at atmospheric pressure and 303～333 K. Thiophene and 2-methyl thiophene can be oxidized over TS-1 only in water or t-butanol solvent. Their oxidation products mainly are sulfuric acid, but their oxidation mechanism is different. Through analyzing the oxidation products we propose that the sulfur atom in thiophene is first oxidized and the thiophene ring in 2-methyl thiophene is initially oxidized. Several other typical organic sulfur compounds such as thioethers, mercaptans and bezothiophenes were also selected and oxidized over TS-1. Methyl thioether and butyl-mercaptan are selectively oxidized using methanol, acetonitrile or water as the solvent. Benzothiophene, dibenzothiophene and 4,6-dimethyl dibenzothiophene are not oxidized obviously over TS-1 for their steric hindrance.