Deep eutectic solvents (DESs) are generally used as attractive solvents or extractants rather than catalysts in the field of synthesis and separation. Herein, dual Brønsted acidic DESs were prepared by mixing sulfonated quaternary ammonium and oxalic acid as extractants and catalysts for deep oxidative desulfurization. Compared to the DESs with single acidic group, the dual acidic DESs exhibited much higher catalytic activity likely due to the synergistic effect. The ¹H NMR study indicated that the weak interaction between DES and sulfur compounds led to a low extraction capacity. However, the sulfur removal could reach 97.7% under optimized reaction conditions. Density functional theory (DFT) calculations demonstrated that sulfonic group and carboxylic group are of equal importance to desulfurization performance. Further, the desulfurization efficiency was also strongly affected by the viscosity of DESs. Here, we put forward a new strategy that the reaction time could be sharply shortened to 40 min and 100 min by adding low viscous acetonitrile and polyethylene glycol into DES to form mixing reaction system, respectively.

在合成和分离领域中，深共晶溶剂（DES）通常用作有吸引力的溶剂或萃取剂，而不是催化剂。在此，通过混合磺化季铵盐和草酸作为萃取剂和用于深度氧化脱硫的催化剂，制备了双重布朗斯台德酸性DES。与具有单一酸性基团的DES相比，双重酸性DES可能表现出更高的催化活性，这可能是由于协同作用。在¹1 H NMR研究表明，DES与硫化合物之间的弱相互作用导致提取能力低。然而，在优化的反应条件下，脱硫率可达到97.7％。密度泛函理论（DFT）计算表明，磺酸基和羧基对脱硫性能具有同等重要性。另外，脱硫效率也受到DES的粘度的强烈影响。在这里，我们提出了一种新的策略，可以通过在DES中加入低粘度乙腈和聚乙二醇分别形成混合反应体系，从而将反应时间急剧缩短至40分钟和100分钟。