Supported metal clusters: Nix/CuZnAl catalysts effectively improve the performance of hydrogen evolution from methylcyclohexane dehydrogenation

Abstract

BackgroundRecently, with the emphasis on hydrogen as alternative clean energy, it is necessary to identify a safe and efficient technique. As a hydrogen storage technique, the liquid organic hydrogen carrier (LOHC) technique has the advantages of high hydrogen storage density, high safety, and low technical cost. MethodsA series of Nix/CuZnAl catalysts were synthesized using co-precipitation and ultrasonic-assisted incipient wetness impregnation methods. Combining XRF, XRD, Uv-vis, H2-TPR, XPS, TEM, and SEM techniques, we show the morphology of the active site during the reaction, and further explore the effects of the formation of the metal cluster NiCuZn. Significant findingsThe multi-metal oxide phase in the sample disappeared after reduction and was transformed into the metal cluster NiCuAl. During the formation of the metal cluster NiCuAl on the catalyst surface, electron transfer towards Ni occurred and the reduction temperature of Ni was lowered, which contributed to the electronic effect and synergy. In this work, The Ni10/CuZnAl catalyst shows the best dehydrogenation activity and selectivity, the catalytic effect was 15–20 times that of the CuZnAl catalyst, and the hydrogen evolution rate reached 77.31 ± 1.25 mmol/gcat/h. Moreover, based on the characterization analysis, the work speculates that the active atom H simultaneously dissociates and desorbs on the Cu and Ni surfaces of the metal cluster. In addition, as a possible active center, with a strong metal-support interaction, the metal cluster NiCuZn promotes the dehydrogenation reaction.