Ti-HMS催化氧化脱除模拟燃料中的硫化物

Catalytic Oxidative Desulfurization of Model Fuel over Ti-HMS Zeolite

将噻吩、苯并噻吩、二苯并噻吩和4,6二甲基二苯并噻吩(DMDBT)分别溶于正辛烷配成模拟燃料,以TiHMS为催化剂,以H2O2为氧化剂,对模拟燃料的氧化脱硫进行了研究,考察了TiHMS的催化活性及硅/钛比和结晶度对催化剂活性的影响.结果表明,在TiHMS上硫化物氧化的难易顺序是由噻吩环上硫原子的电子云密度和硫化物分子的空间位阻共同决定的;氧化反应发生在分子筛孔道内,骨架钛原子为活性中心;DMDBT在TiHMS上的氧化脱除效果比在TS1,Tiβ或TiMCM41上好.随着TiHMS中硅/钛比的增大,DMDBT的脱除率降低;随着TiHMS分子筛结晶度的升高,DMDBT的脱除率升高.

With Ti-HMS as the catalyst and with H2O2 as the oxidant, the oxidative desulfurization (ODS) of thiophene ( Th), benzothiophene ( BT), dibenzothiophene ( DBT) and 4,6-dimethyl dibenzothiophene (DMDBT) in a model fuel was studied. The ODS reactivity of these compounds over Ti-HMS was measured and the effects of SiO2/TiO2 ratio and crystallinity of Ti-HMS on the sulfur removal were investigated. The order of ODS reactivity over Ti-HMS was as follows: DBT > BT > DMDBT > Th, which was determined by the electron density on sulfur atom in thiophene ring and steric hindrance of the sulfur compounds. DMDBT was oxidized more efficiently over Ti-HMS than over TS-1, Ti-beta or Ti-MCM-41. The sulfur compounds were oxidized in the channel of Ti-HMS and framework titanium atoms were the active sites. With the decrease of n (Sio(2)) /n (TiO2) ratio from 200 to 25, the DMDBT removal increased from 39. 6 % to 83. 6 %. With the increase of relative crystallinity of Ti-HMS from 43. 0 % to 96. 4 %, the DMDBT removal increased from 33. 0 % to 44. 8 %. When the relative crystallinity of Ti-HMS increased to 100 %, the DMDBT removal increased dramatically to 71. 4 %. Both the mesopore framework and framework titanium atoms were necessary to the ODS of DMDBT.