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

Author:
Jiang, Wei, Dong, Lei, Liu, Wei, Guo, Tao, Li, Hongping, Zhang, Ming, Zhu, Wenshuai, Li, Huaming
Source:
RSC advances 2017 v.7 no.87 pp. 55318-55325
ISSN:
2046-2069
Subject:
aromatic compounds, catalysts, catalytic activity, desulfurization, fuels, hydrogen peroxide, oxidants, oxidation, solvents, sulfur, temperature
Abstract:
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%.
Agid:
6422000