高效钒基催化剂用于低温船舶尾气氮氧化物净化研究

Nitrogen oxides (NOx), emitted from marine diesel engine, can induce severe environmental pollutions and health damage. The selective catalytic reduction of NOx by NH3 (NH3-SCR) is one of the most promising technologies for NOx emission control from stationary and mobile sources. Due to some inevitable problems, such as high operation temperature, narrow operation temperature window and high conversion of SO2 to SO3, traditional vanadium-based catalyst could not meet the NOx emission standard from marine low speed diesel engine. In this study, we will investigate deeply the active microstructure of vanadium-based catalysts in the process of NH3-SCR and SO2 oxidation. By accurately controlling of microstructure, the highly active centre structure will be constructed. SO2 effect mechanism on the catalyst will be deeply studied. Therefore, the catalyst with low loading of vanadium with excellent NH3-SCR performance and low SO2 oxidation activity will be achieved. In addition, some characterization methods will be used for establishing the structure-activity relationships of the catalysts in NH3-SCR reaction and clarifying the reaction mechanism on the catalysts, which will be helpful for the improvement of the catalysts. This study will be meaningful and helpful for NOx abatement from marine low speed diesel engine.

船舶柴油机尾气排放大量的氮氧化物，对环境和人体健康造成严重的危害。NH3选择性催化还原NOx（NH3-SCR）是去除固定源和移动源NOx应用最为广泛的技术之一。传统的钒基催化剂存在操作温度高、操作温度窗口窄、SO2氧化等问题，难以满足船舶低速柴油机NOx排放要求。本项目以低钒催化剂为研究对象，深入剖析低钒催化剂在NOx净化及SO2氧化反应中活性结构的微观特征，通过微观结构的精确调控，构建低钒催化剂低温NOx还原的高活性中心结构；深入解析硫作用机制，并探讨氧化还原位点与酸性位点的紧密耦合效应，以实现NOx净化低温活性优异、SO2氧化性能低的低钒催化剂合成；采用多种表征手段，阐明催化剂在NH3-SCR反应中的构效关系和反应机理，指导高性能催化剂的设计。本项目研究工作可为钒基催化剂在船舶低速柴油机尾气NOx净化过程的实际应用提供基础数据和技术储备，具有重要的科学价值和实际意义。

船舶柴油机尾气排放大量的氮氧化物，对环境和人体健康造成严重的危害。NH3选择性催化还原NOx（NH3-SCR）是去除固定源和移动源NOx应用最为广泛的技术之一。传统的钒基催化剂存在操作温度高、操作温度窗口窄、SO2氧化等问题，难以满足船舶低速柴油机NOx排放要求。因此我们通过钒基催化剂表面硫含量的调控，设计合成具有聚合态钒氧物种活性中心结构的低钒负载量低温活性催化剂。并通过量子化学计算方法从原子水平阐明了钒基SCR催化剂去除NOx的微观基元反应全过程，明确了聚合态下钒物种间的耦合作用缩短了活性位再生的反应路径，并显著降低决速步能垒。因此，理论和实验均证明低聚态钒氧物种的催化活性明显高于单体钒氧物种，是低温SCR去除NOx的活性位。在抗硫性能研究方面，通过Nb的掺杂提高催化剂的酸性，抑制了表面硫酸盐的形成，而催化剂表面主要吸附硝酸盐，参与SCR反应，因此能够显著提高钒基催化剂的抗硫性能。钒基催化剂不同气氛的处理改变催化剂表面钒物种的状态，进而影响催化剂的低温SCR活性。本项目研究工作可为钒基催化剂在船舶低速柴油机尾气NOx净化过程的实际应用提供基础数据和技术储备，具有重要的科学价值和实际意义。