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Preparation and Performance Analysis of Anion Exchange Membranes Modified with Chromotropic Acid Grafted 18⁃Crown⁃6 Ether on Polyvinyl Alcohol
Ningda ZHANG, Lulu WANG, Yang ZHANG, Fan ZHANG, Jilin WANG
Abstract49)   HTML1)    PDF (4156KB)(0)      

The quaternary ammonium group (QA) commonly used in conventional anion exchange membranes (AEMs) has a low dissociation constant with OH-, resulting in poor conductivity. The crown ether group can significantly enhance the ion exchange capacity (IEC) and OH- conduction efficiency of AEMs due to its ability to form positively charged complexes with alkali metal cations. Meanwhile, the ether bond in the crown ether ring exhibits good alkali and chemical stability. In view of the above advantages, a series of AEMs grafted with bi?crown ethers were successfully prepared by grafting dibenzo?18?crown?6?ether?modified polyvinyl alcohol (PVA) via metastable acid. The results showed that the bi?crown ether anion?exchange membranes exhibited higher OH-selectivity and chemical stability compared with the mono?crown ether membrane materials; the prepared AEMs exhibited good OH- selectivity and chemical stability in terms of electrical conductivity (conductivity of 165.5 mS/cm at 80 ℃), mechanical properties (tensile strength of 47 MPa at room temperature), and alkali stability (only 4.52% decrease in conductivity after immersion in KOH at a concentration of 6 mol/L for 168 h), and the high efficiency electrolysis of water to produce hydrogen based on platinum charcoal as the anode material, and the efficiency of electrolytic reduction reached 80%.

2025, 45 (5): 9-17. DOI: 10.12422/j.issn.1672-6952.2025.05.002
Preparation and Characterization of Iron Modified MoNi/γ⁃Al 2O 3 Catalysts
Xiaoxue Mu, Wei Ding, Xiaofan Zhang, Yongchuan Dai, Zhongxing Geng, Yu Li
Abstract721)   HTML20)    PDF (1218KB)(579)      

The hydrogenation catalysts with Mo and Ni as active centers were modified with macroporous nano?alumina as carrier and iron as auxiliary agent, and Fe?Mo?Ni and Fe?Ni catalysts were prepared by secondary nano?self?assembly method respectively. The experimental results show that the iron modified catalysts MNF?70C and NF?70C have bimodal pore structure, the larger most probable pore diameter is 50.0 nm and 40.0 nm respectively, and the smaller most probable pore diameter is 5.5 nm. It can be seen that under the action of complexing agent and promoter Fe, Fe, Mo and Ni in MNF?70C catalyst form a large number of nano self?assemblies in the form of metal bonds on the inner and outer surfaces of macroporous alumina, which are more evenly dispersed and have more pores suitable for hydrogenation reaction. The pore size distribution of MNF?70C and NF?70C catalysts in the range of 6.0~60.0 nm reached 78.05% and 72.80% respectively. It shows that the addition of structural assistant iron improves the dispersion of active metals, so as to effectively improve the pore size distribution of the catalyst. The characterization analysis of CO adsorption, H2?TPR TEM and XPS further shows that the Fe modified catalyst has linear adsorption for CO, its reduction temperature is low, and it has been evenly dispersed in the form of nanoparticles, with more catalytic active centers, indicating that this kind of catalyst has better hydrogenation catalytic activity. Because Fe is cheap, the addition of additives can improve the quality of the oil after hydrogenation or reduce the amount of catalyst active metal, so as to reduce the cost of synthetic catalyst, which is suitable for the development of heavy oil hydrogenation catalyst for industrial application.

2022, 42 (4): 6-10. DOI: 10.3969/j.issn.1672-6952.2022.04.002