Study On Sulfur Removal Of Thiophene By Slective Oxidation And Catalytic Conversion In Hydrogen Atmosphere

Thiophene grievously influences the production of high quality chemicals and clean gasoline. This paper mainly studies on the sulfur removal of thiophene by slective oxidation and catalytic conversion in hydrogen atmosphere.The study on the selective oxidation of thiophene in liquide phase was carried out with coking benzene raw material and TS-1/H₂O₂ system. The effect of reaction temperature and H₂O₂/Thiophene molar ratio were systematically investigated. Besides, oxidation products, regeneration times and the changes physicochemical properties of catalysts were studied. Results show that, under the conditions of reaction temperature of 70℃ and the ratio of H₂O₂/thiophene>l:4, the removal percentage of sulfur in cocking benzene can reach 98% within 6h's reaction.The study on the removal of thiophene on solid acid catalyst in gas-solid phase in the presence of hydrogen was performed with a pulsed micro-reactor-chromatography system and modified nano-HZSM-5 zeolite. GC-MS was used to analysis the distribution of reaction product under different conditions. Results show that, in addition to the formation of H₂S by desulphurization, new sulfur-containing compounds such as t-butyl sulfalcohol, 2-methyl-thiophene, 3-methylthiophene and benzothiophene are also produced during the conversion of thiophene over the different catalysts. Both atmosphere and the acidity of catalyst have significant influence on product distribution. Compared with nitrogen, the use of hydrogen as carrying gas can pronouncedly promote the conversion and desulphurization of thiophene even if under atmospheric condition. Such an effect of hydrogen carrier is connected to the supply of hydrogen atoms for the cracking of thiophene via the activation of hydrogen molecules on Lewis acid sites. It is observed that the effect of hydrogen carrier can be enhanced by decreasing the concentration and the strength of Bronsted acid site of the catalyst through suitable modifications and increasing the ratio of L acid sites to B acid sites. Treating the nano-HZSM-5 zeolite with pure steam or with ammonia-containing steam has no obvious impact on sulfur removalof thiophene. However, the modification of the zeolite with La₂O₃ and/or NiO can remarkably improved the desulfurization capability of the catalysts.