Main content area

Designing multifunctional SO₃H-based polyoxometalate catalysts for oxidative desulfurization in acid deep eutectic solvents

Jiang, Wei, Dong, Lei, Liu, Wei, Guo, Tao, Li, Hongping, Zhang, Ming, Zhu, Wenshuai, Li, Huaming
RSC advances 2017 v.7 no.87 pp. 55318-55325
aromatic compounds, catalysts, catalytic activity, desulfurization, fuels, hydrogen peroxide, oxidants, oxidation, solvents, sulfur, temperature
Deep eutectic solvents (DESs) are ‘green’ sustainable solvents with wide applications such as extractive desulfurization of fuel; however, their low extraction efficiency is a major limitation to such applications. In this work, several SO₃H-functionalized polyoxometalates were prepared and applied to oxidative desulfurization of fuels with acidic DESs as extractants and 30 wt% of H₂O₂ as an oxidant. Compared with neutral POM catalysts, acidic catalysts, such as [PSTEtA]₃PW₁₂O₄₀, exhibited higher catalytic performance with 100% desulfurization efficiency. However, in the absence of DESs sulfur removal was only 9.6% with [PSTEtA]₃PW₁₂O₄₀ used as a catalyst. To study the role of the DESs, three types of DESs were evaluated on extraction and oxidation of dibenzothiophene (DBT), with acidic DES ChCl/2Ac exhibiting the best performance. The effects of different reaction conditions, such as the amount of H₂O₂ and ChCl/2Ac, reaction temperature and time, different sulfur compounds, and fuel composition, were investigated. Combined with the kinetic study, results suggested that oxidation of DBT was attributed to a pseudo-first-order kinetic reaction. The activities of different sulfur compounds decreased in the order of DBT > 3-methylbenzothiophene (3-MBT) > 4-methyldibenzothiophene (4-MDBT) > 4,6-dimethyldibenzothiophene (4,6-DMDBT) > benzothiophene (BT). Compared with aromatics, the sulfur removal could be strongly affected by olefins, showing a drop of up to 66.6%.