Because of its unique pore structure,good hydrothermal stability and high specific surface area,hierarchical TS-1 zeolite(HTS-1)has become an important catalyst for the deep oxidative desulfurization of fuel oils.In this work,HTS-1 has been successfully synthesized by a hydrothermal crystallization method using the C-SiO_(2)composite as both silicon source and mesoporous template,tetrapropylammonium hydroxide as microporous template,and tetrabutylorthotitanate as titanium source.The C-SiO_(2)composite is obtained by mild carbonization of the SiO_(2)/T-40(Tween 40)xerogel,which is prepared by the two step sol-gel method.The reaction conditions for the oxidative desulfurization(ODS)of dibenzothiophene(DBT)and 4,6-dimethyldibenzothiophene(4,6-DMDBT)over HTS-1 are optimized systematically,and the recycling performances of HTS-1 are investigated in detail.After the 15th run,HTS-1 still maintains high DBT conversion(90.6%)and 4,6-DMDBT conversion(86.0%)without deactivation.The samples before and after recycle tests are characterized by XRD,FT-IR,CHN analysis,UV-Vis and SEM techniques.The results indicate that the crystal structure and morphology of regenerated HTS-1 samples are well kept,which accounts for the good structural stability and reusability of HTS-1.In addition,active intermediates for the ODS of bulky organic sulfides over HTS-1,i.e.,Ti-peroxo(Ti-OOtBu)species,are captured by the UV-Vis technique.Finally,a possible reaction mechanism for the ODS process over HTS-1 is proposed.
Jinglong HuaiXiaoxue LiuYinhai ZhangYang YangYan GouLi QinJinling ShanYancheng ZhengHao Li
