Mechanical alloying technique was used to prepare the Co 0.9 Cu 0.1 Si alloy. Composite materials of Co 0.9 Cu 0.1 Si doping with different amounts of multi-walled carbon nanotubes (MWCNTs) or lithium modified MWCNTs (Li-MWCNTs) were obtained via ball-milling to improve the hydrogen storage performance of Co 0.9 Cu 0.1 Si. XRD , SEM and TEM were used to analysis the structural properties of the samples. A three-electrode battery system was carried out to test the electrochemical properties . After the addition of MWCNTs, the composites showed higher discharge capacity, stronger HRD, better cyclic stability and lower charge-transfer resistance than the original Co 0.9 Cu 0.1 Si alloy. The electro-catalytic function of MWCNTs, the reduction of particle size and the raise of specific surface area for Co 0.9 Cu 0.1 Si alloy may provide larger electrochemically accessible area and rapid channel for hydrogen transportation , which are important to enhance the electrochemical performance of the alloy. Moreover, a further improvement was achieved after the addition of Li-MWCNTs, illustrating that the MWCNTs and lithium species had synergistic effects in improving the discharge capacity and reaction kinetics of the Co 0.9 Cu 0.1 Si alloy electrode. As the weight ratio of the alloy and Li-MWCNTs was 15:1, the optimal discharge capacity of 624.4 mAh/g and the highest capacity retention of 67.5% were achieved.
The hydrogenation of 2,4-dinitrotoluene (2,4-DNT) into 1-methyl-2,4-cyclohexanediamine (2,4-MCHD), a significant yet underutilized raw material for the synthesis of methylcyclohexane diisocyanate (HTDI) with exceptional properties, represents one of the most promising reactions for the development of diisocyanate chemical processes. In this study, we developed a highly efficient and stable heterogeneous catalytic system for the direct hydrogenation of 2,4-DNT to 2,4-MCHD using Li-modified γ-Al 2 O 3 supported Ru nanoclusters (Li-modified-Ru/γ-Al 2 O 3 ). Under mild reaction conditions, we successfully inhibited side reactions, such as deamination, achieving a selectivity exceeding 95% for 2,4-MCHD, while the conversion of 2,4-DNT surpassed 99%. Kinetic studies revealed that the hydrogenation of 2,4-DNT in this system occurs as a tandem reaction, with the hydrogenation of the benzene ring identified as the rate-determining step. Investigations into the structure–activity relationship indicated that the valence state of the Ru nanocluster, the acid-base properties of the catalyst, the modification by Li, and the synergistic effects of various elements within the catalyst are critical factors contributing to the high activity and stability of the Li-modified-Ru/γ-Al 2 O 3 catalyst for the hydrogenation of 2,4-DNT to produce 2,4-MCHD. This work represents the first example of the direct hydrogenation of dinitroaromatic compounds to yield diamino aliphatic compounds and provides a solid foundation for understanding such reaction systems.
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