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.
Yuanyuan Li,Qiang Li,Nan Zhu,Zhuxian Gao,Yulong Ma
The graphene oxide (GO) was covalently coupled to the surfaces of silica gel (SiO 2 ) microspheres by amide bond to get the graphene oxide@silica gel (GO@SiO 2 ). Then, the GO@SiO 2 was reduced with hydrazine to the reduced graphene oxide@silica gel (rGO@SiO 2 ), and the cellulose derivatives were physically coated on the surfaces of rGO@SiO 2 to prepare a chiral stationary phase (CSP) for high performance liquid chromatography. Under the optimum experimental conditions, eight benzene-enriched enantiomers were separated completely, and the resolution of trans-stilbene oxide perfectly reached 4.83. Compared with the blank column of non-bonded rGO, the separation performance is better on the new CSP, which is due to the existence of rGO to produce special retention interaction with analytes, such as π-π stacking, hydrophobic effect, π-π electron-donor–acceptor interaction, and hydrogen bonding. Therefore, the obtained CSP shows special selectivity for benzene-enriched enantiomers, improves separation selectivity and efficiency, and rGO plays a synergistic effect with cellulose derivatives on enantioseparation.
We report the design and synthesis of a novel pyridine-containing triamine monomer, 2,6-bis(4-aminophenyl)-4-(4-aminophenoxy)pyridine (BAAP), through combining the nucleophilic aromatic substitution with modified Chichibabin reaction and hydrazine hydrate reduction. Based on it, a novel three-step route was applied in order to obtain a series of new polyimides, containing phthalimide as pendent group and pyridine moieties in main chains. The three-step route consisted of terminating the triamine by incorporating phthalic amic acid as pendant, ring-opening polymerization to form poly(amic acid)s and further chemical imidization to acquire polyimides. Nuclear Magnetic Resonance Spectroscopy ( 1 H-NMR) was used for chemical structural characterization, and the results indicated the various forms of BAAP and branched structure units in the obtained polyimides. The morphology structures of the polyimides were evaluated by X-ray diffraction patterns, and the d -spacing values were found in the range of 4.14–4.65 Ǻ. Most of the resulting polyimides were soluble in polar aprotic solvents, such as NMP, DMF, DMAc, DMSO, and so on. Meanwhile, the polyimides exhibited excellent thermal stability, with the decomposition temperature at 5 and 10 % weight loss temperatures in the ranges of 399.1–461.1 °C and 481.1–566.9 °C, respectively. The polyimides, based on 6FDA, possessed the best comprehensive thermally stable and soluble performance.
危险品化学品经营许可证（带存储）