Deep oxidative desulfurization of dibenzothiophene by novel POM-based IL immobilized on well-ordered KIT-6

Abstract

A novel POM-based IL immobilized on well-ordered KIT-6 catalyst [Omim] 3 PMo 12 O 40 /KIT-6 was successfully synthesized. Complete desulfurization (100%) can be achieved within 80 min for DBT model oil (S: 1000 ppm) under 60 °C and O/S = 5 using tertbutyl hydroperoxide (TBHP) as an oxidant. The hydroxyl radicals (•OH) was proved to be the most important reactive species by a scavenger experiment. The synergistic effect of super catalytic ability of [PMo 12 O 40 ] 3− Keggin structure and the absorption ability of KIT-6 and [Omim] + contributes to the excellent S conversion rate. • A novel catalyst [Omim] 3 PMo 12 O 40 /KIT-6 was synthesized by impregnation method. • Desulfurization efficiency of 100% can be achieved within 80 min for dibenzothiophene model oil (S: 1000 ppm). • Different substrates were used as reactants and the oxidation activity decreases in the order of DBT > 4,6-DMDBT > BT. • The hydroxyl radicals (•OH) played an indispensable role in oxidative desulfurization. • The synergistic effect of [Omim] + , PMo 12 O 40 3- and KIT-6 contributes to the excellent catalytic activity. Oxidative desulfurization (ODS) process is one of the most promising desulfurization technologies because of its energy-efficient and mild operation condition. In this study, a novel active phase POM-based IL-[Omim] 3 PMo 12 O 40 was synthesized, and then it was supported on well-ordered KIT-6. [Omim] 3 PMo 12 O 40 /KIT-6 catalyst was used in the dibenzothiophene (DBT) and real diesel oxidative desulfurization with tertbutyl hydroperoxide (TBHP) as an oxidant. The composite materials [Omim] 3 PMo 12 O 40 and [Omim] 3 PMo 12 O 40 /KIT-6 catalysts were characterized by means of Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photo-electron spectroscopy (XPS) and nitrogen adsorption–desorption analysis. [Omim] 3 PMo 12 O 40 /KIT-6 catalyst showed high catalytic activity, at the optimal conditions of m catalyst /V Oil = 0.1 g/20 ml, m [Omim]3PMo12O40 /m KIT-6 = 30%, O/S = 5 (molar ratio), 60 °C, S of 1000 ppm (DBT in n-octane) can be completely removed within 80 min due to the superior mass transfer ability of the cubic I a 3 _ d mesoporous structure of KIT-6 and excellent catalytic ability of [Omim] 3 PMo 12 O 40 . In addition, [Omim] 3 PMo 12 O 40 /KIT-6 could be easily separated and the catalytic activity remains stable after 9 cycles. The ODS reaction mechanism is also investigated.