Oxidative desulfurization is a promising way to produce, under mild conditions, clean ecological fuels with ultra-low sulfur content. Herein, we present for the first time heterogeneous catalysts based on natural aluminosilicate nanotubes (halloysite) loaded with transition metal oxides for oxidative sulfur removal using hydrogen peroxide as environmentally safe oxidant. The halloysite nanotubes (HNTs) provide acid sites for C–S bond scission, while the Mo and W oxides act as hydrogen peroxide activators. The structure and acidity of both the clay support and catalysts were investigated by low-temperature nitrogen adsorption/desorption, Fourier-transform infrared spectroscopy, X-ray fluorescence analysis, and transmission electron microscopy techniques. These clay-based catalysts revealed the high activity in the oxidation of various classes of sulfur-containing compounds (sulfides, heteroatomic sulfur compounds) under mild reaction conditions. The conversion of various substrates decreases in the following trend: MeSPh > Bn2S > DBT > 4-MeDBT > BT, which deals with substrate electron density and steric hindrance. The influence of the temperature, oxidant to sulfur molar ratio, and reaction time on catalytic behavior was evaluated for Mo- and W-containing systems with various metal content. The complete oxidation of the most intractable dibenzothiophene to the corresponding sulfone was achieved at 80 °C and H 2 O 2 :S = 6:1 (molar) for 2 h both for Mo- and W-containing systems. These transition metal oxides HNTs supported catalysts are stable for 10 cycles of dibenzothiophene oxidation, which makes them promising systems for clean fuel production.

中文翻译：

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天然粘土纳米管负载的Mo和W催化剂，用于模型燃料的彻底氧化脱硫

氧化脱硫是一种在温和条件下生产具有超低硫含量的清洁生态燃料的有前途的方法。本文中，我们首次提出了基于天然铝硅酸盐纳米管（硅藻土）的非均相催化剂，该催化剂负载有过渡金属氧化物，可使用过氧化氢作为对环境安全的氧化剂去除氧化硫。埃洛石纳米管（HNT）为C–S键断裂提供酸性位点，而Mo和W氧化物则充当过氧化氢活化剂。通过低温氮吸附/解吸，傅立叶变换红外光谱，X射线荧光分析和透射电子显微镜技术研究了粘土载体和催化剂的结构和酸度。这些基于粘土的催化剂显示出在温和的反应条件下，各种类型的含硫化合物（硫化物，杂原子硫化合物）具有很高的氧化活性。各种底物的转化率呈以下趋势降低：MeSPh> Bn2S> DBT> 4-MeDBT> BT，这涉及底物电子密度和空间位阻。对于各种金属含量的含Mo和W的体系，评估了温度，氧化剂与硫的摩尔比以及反应时间对催化性能的影响。对于含钼和含钨的体系，在80°C和H 2 O 2：S = 6：1（摩尔）下，最难处理的二苯并噻吩被完全氧化为相应的砜达2小时。