Preparation of Cu-Ni/ZrO2 and Cu/ZrO2-Co3O4 catalysts by co-precipitation-hydrazine hydrate reduction method and their efficient dehydrogenation mechanism for diethanolamine

The catalytic dehydrogenation of diethanolamine to prepare iminodiacetic acid has attracted considerable research interest. However, the lack of understanding of the structure-activity relationship of the reaction can present a challenge to the control of the catalytic behavior. Concurrently, improving the catalytic performance and reducing the cost have also become urgent issues that require resolution. This work examined the catalytic mechanism of several Cu-Ni X /ZrO 2 catalysts, differing in Cu/Ni ratios, prepared by H 2 reduction, in the context of DEA dehydrogenation to elucidate the structure-activity connection and probable reaction mechanism. Subsequently, a strategy has been put out to generate metal (Ni and Co)-doped copper-zirconium catalysts using the co-precipitation-hydrazine hydrate reduction process. The synergistic effect between metals was combined with the improvement of the surface reaction of the catalyst by hydrazine hydrate through a more efficient preparation method, thereby enhancing the catalyst's overall performance. The representative catalyst Cu-Ni/ZrO 2 required a hydrazine hydrate reduction temperature and time of 40 °C and 30 min, and after 65 min of reaction, it exhibited a high conversion rate (96.3 %) and yield (93.7 %), and after five cycles, both the conversion rate and yield exceeded 85 %. Various characterization techniques have confirmed that Ni doping induced an alloying effect and a size effect. Additionally, the hydrazine hydrate reduction method was discovered to augment the specific surface area, surface hydroxyl groups, hydrophilicity, and optimize the pore size distribution of the catalyst while also regularizing its morphology, thereby significantly enhancing the activity and stability of the metal-doped copper-zirconium catalyst. This paper discussed the correlation between catalyst structure and reaction performance, as well as the catalytic conversion mechanism, which is anticipated to provide a novel reference for the preparation, performance control, and potential applications of dehydrogenation catalysts.