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    贵金属催化剂制备及其有机液态载体催化加氢性能研究

    Preparation of noble metal catalysts and their catalytic hydrogenation performance for liquid organic hydrogen carriers

    • 摘要: 氢能作为质量热值高、清洁的可再生能源,在交通、化工、航空航天等领域展现出广阔应用前景。为实现能源安全与“双碳”目标,发展可再生氢能及其储运技术成为关键环节。有机液体储氢(LOHC)以其高密度氢储存能力、良好热力学性质和兼容现有燃料基础设施的优势,成为绿氢储运的重要方式之一。然而,其加氢/脱氢效率高度依赖催化剂性能,现有研究多聚焦单一贵金属催化剂的开发,但因制备方法、载体特性及反应条件差异导致活性数据难以横向对比,制约了构效关系的深入解析与高效催化剂的优化设计。面向有机液体载体高效加氢的需求,本文以单苄基甲苯(H0-MBT)和二苄基甲苯(H0-DBT)为反应底物,采用过量浸渍法平行制备了Ru/Al2O3、Rh/Al2O3、Pd/Al2O3和Pt/Al2O3贵金属加氢催化剂。通过TEM、H2-TPR、N2吸附-脱附、XRD和XPS等手段系统表征其物理化学性质,并对其催化加氢性能进行了系统比较研究。结果表明:Pt/Al2O3因γ-Al2O3表面五配位Al3+位的强锚定作用,金属分散性最佳、平均粒径最小(<2 nm)。催化加氢反应性能显示,Pt/Al2O3活性最高,完全加氢时间分别为80 min和120 min,显著优于其他贵金属催化剂。在催化剂负载Pt质量分数为0.5 %、5 MPa H2、600 r/min条件下,H0-MBT和H0-DBT的最佳反应温度分别为160 ℃和180 ℃。该研究为高效LOHC加氢催化剂设计与工艺优化提供了基础数据支撑。

       

      Abstract: Hydrogen, as a clean renewable energy with a high calorific value, exhibits broad application prospects in transportation, chemical engineering and aerospace. To achieve energy security and carbon neutrality goals, the development of renewable hydrogen and its storage and transportation technology have become a crucial aspect. Liquid Organic Hydrogen Storage (LOHC) has emerged as a significant pathway for green hydrogen storage and transportation due to its high hydrogen storage capacity, favorable thermodynamic properties, and compatibility with existing fuel infrastructure. However, the efficiency of its hydrogenation or dehydrogenation processes is highly dependent on catalyst performance. Existing research primarily focuses on the development of single noble metal catalysts. Nevertheless, disparities in preparation methods, support characteristics, and reaction conditions have led to difficulties in direct cross-comparison of activity data, hindering the deep analysis of structure-activity relationships and the rational design of highly efficient catalysts. Addressing the demand for efficient hydrogenation of organic liquid carriers, this study synthesized Ru/Al2O3, Rh/Al2O3, Pd/Al2O3, and Pt/Al2O3 noble metal hydrogenation catalysts using the excess impregnation method in parallel, with monobenzyltoluene (H0-MBT) and dibenzyltoluene (H0-DBT) as reaction substrates. The physic and chemical properties were systematically characterized using TEM, H2-TPR, N2 physisorption-desorption, XRD, and XPS. Subsequently, their catalytic hydrogenation performance was comparatively investigated. Results indicated that Pt/Al2O3, attributed to the strong anchoring effect of pentacoordinate Al3+ sites on the γ-Al2O3 surface, exhibited the best metal dispersion and the smallest average particle size (<2 nm). In catalytic hydrogenation reactions, Pt/Al2O3 demonstrated superior activity, achieving complete hydrogenation in 80 min for H0-MBT and 120 min for H0-DBT, significantly outperforming other precious metal catalysts. Under optimized conditions of 0.5% Pt loading, 5 MPa H2 and 600 r/min, the optimal reaction temperatures for H0-MBT and H0-DBT hydrogenation were found to be 160 ℃ and 180 ℃, respectively. The design of highly efficient LOHC catalysts and the optimization of related processes are supported by fundamental data provided by this research.

       

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