新型非金属功能化低共熔溶剂催化氧气氧化燃油脱硫的研究

The sulfur compounds in diesel fuel, which are converted to SOx during the combustion in car engines, has shown an adverse impact on the environment. Thus, production of ultra-low-sulfur diesel has become a major task of refineries all over the world. Deep oxidative desulfurization with oxygen or air as oxidant has always been a promising research subject. In our research, functional N-Hydroxyphthalimide (NHPI) derivatives will be synthesized and designed as hydrogen bond donors. Quaternary ammonium salts with various carbon chains are used as hydrogen bond acceptor. Then the novel deep eutectic solvents (DESs) obtained by mixing the two compounds are used to investigate the activity on deep oxidative desulfurization of fuels in the presence of molecular oxygen. The nature of substituents in NHPI derivatives and the type of the cation in quaternary ammonium salts are investigated to study the catalytic ability and extractive performance. The investigation of in situ spectra and electrochemistry experiments is used to provide ground for redox activity and oxidative desulfurization mechanism. During the oxidative desulfurization process, the novel DESs not only possess the extractive performance but also activate oxygen. Therefore, So this research may provide a new method for deep oxidative desulfurization of fuels, which is greener and more cost-effective.

柴油中硫化物燃烧后会转化为SOx，是环境污染的主要因素之一，因此生产超低硫含量的柴油是目前全世界炼油工业的一个主要任务，而以氧气为氧源进行燃油深度氧化脱硫是一项非常有前景的研究课题。本课题拟将可活化氧气的NHPI衍生物为氢键供体，不同碳链长度的季铵盐为氢键受体，合成一类新型的功能化低共熔溶剂，考察其在氧气作用下深度氧化脱除燃油中噻吩硫的性能。调控氢键供体上取代基的性质、卤代盐阳离子的种类和碳链长度来改变低共熔溶剂的催化性能及萃取能力，运用原位谱学和电化学实验等方法研究新型低共熔溶剂的氧化还原性和催化氧化脱硫机理，关联低共熔溶剂的组成、结构与催化性能，为其可控合成和应用提供理论依据。在柴油脱硫反应中，这类新型低共熔溶剂既具有传统低共熔溶剂的萃取性能，又具有活化氧气的能力。因此，该研究工作的开展，不仅提出了一类新型氧化脱硫体系，也可能开辟一条更加绿色经济的氧化脱硫新途径。

近年来，含硫燃油的大量使用导致SOx和颗粒物的过度排放，是大气污染的重要影响因素之一。本课题选用不同种类的氢键受体和供体，构建了20余种新型的低共熔溶剂，并通过NMR、IR等手段对其进行表征。首先将低共熔溶剂应用于柴油的萃取脱硫，发现氢键受体和供体的摩尔比对低共熔溶剂的性质产生较大的影响，通过筛选，三乙胺与丙酸以摩尔比为1:3得到低共熔溶剂与油品几乎不互溶，且对 DBT具备较好的萃取效果，并通过实验和理论计算的方法推断出了萃取的作用机理。为了实现柴油的超深度脱硫，将低共熔溶剂作为萃取剂，结合杂多酸盐催化剂，形成低共熔溶剂萃取耦合氧化脱硫体系，实验研究表明，该体系的脱硫活性受到低共熔溶剂的酸碱性、杂多酸盐的结构影响，通过催化剂和低共熔溶剂的匹配，可实现对柴油的脱硫率可达到99%以上。为了实现氧气为氧化剂的深度氧化脱硫，将N-羟基邻苯二甲酰亚胺（NHPI）为活性中心，在微量钴盐为助催化剂时，碳纳米管负载的NHPI催化剂可活化氧气进行柴油的超深度脱硫，柴油中硫含量可降低至10 mg/kg以下，达到目前最新的柴油国VI排放标准。本研究选取低共熔溶剂为萃取剂及反应介质，不仅实现了柴油的超深度脱硫，还丰富了低共熔溶剂的种类，对于实际工业应用具有重要的参考价值。