Deep desulfurization of diesel by ionic liquid extraction coupled with catalytic oxidation using an Anderson-type catalyst [(C4H9)4N]4NiMo6O24H6

Authors:   Hongying Lü, Wanzhong Ren, Hongyan Wang, Yun Wang, Wei Chen, Zhanghuai Suo

Abstract:
A series of Anderson-type Q₄NiMo_6−xWxO₂₄H₆ (x = 0, 2, 4, 6) catalysts were synthesized and employed in ionic liquids (ILs) extraction coupled with catalytic oxidation desulfurization systems (ECODS) for removal of benzothiophene (BT), dibenzothiophene (DBT) and their derivates in a model diesel and an actual commercial diesel. The catalyst [(C₄H₉)₄N]₄NiMo₆O₂₄H₆ in ECODS system, containing H₂O₂ and [Bmim]PF6, exhibited so high catalytic activity that DBT removal can reach 98% at 30 ^◦C in 3 h. The catalytic activity of the catalysts depends on the polyoxometalate anion and cation. The DBT removal gradually increases with the increasing of the molybdenum ions in the Anderson-type polyoxometalates. Quaternary ammonium cations can effectively promote the oxidative desulfurization reaction, which was confirmed by the presence of the mixed-valence molybdenum ions in the Anderson-type polyoxometalate catalyst. ILs was used as an extractant, however it also promoted the oxidative desulfurization reaction greatly. The reaction rate was so sensitive to the oxidant dosage that the removal DBT first increased and then decreased with the increasing of O/S molar ratio. The change is probably due to the introduction of excess water in the system. Sulfur removal selectivity for S-compounds followed the order of DBT > 4-MDBT > 4,6-DMDBT > BT > 5-MBT. The reactivity of these S-compounds is sensitive to the electron density on sulfur atoms and the steric hindrance of the substituted groups of S-compounds. The sulfur level of an actual commercial diesel can be decreased from 700 to about 30 ppm after desulfurization reaction. The desulfurization system for the actual commercial diesel can be recycled ten times with an unnoticeable decrease in activity.

Keywords:
Ionic liquid
Oxidative desulfurization
Diesel
Anderson-type catalyst

Published in: Applied catalysis A: General  (Volume 453, Pages 1-402, 26 February 2013)

Publisher: Elsevier

ISSN Information: 0926-860X

Deep desulfurization of diesel by ionic liquid extraction coupled with catalytic oxidation using an Anderson-type catalyst [(C4H9)4N]4NiMo6O24H6

Bình luận của bạn

*

*

*

*

 Captcha

Gửi bình luận nhập lại