Cu-based catalysts applied in ethynylation reaction of formaldehyde for 1,4-butynediol synthesis has been widely concerned. The activity and stability of Cu-based catalyst is still a challenging task in this field. Here, Cu–Zn catalysts derived from ZIF-8 are prepared by a coprecipitation method and applied in ethynylation reaction of formaldehyde. All catalysts were characterized through thermogravimetric, x-ray diffraction, N 2 physical adsorption–desorption, transmission electron microscopy, H 2 -temperture-programmed reduction, x-ray photoelectron spectroscopy, and Raman and Fourier transform infrared analysis. The effect of calcination temperature of ZIF-8 on the catalyst structures and ethynylation performances are all investigated. The results show that CuO 5h -ZnO 400 catalyst has the best catalytic activity, with a formaldehyde conversion of 98% and 1,4-butynediol selectivity of 100%. It is mainly due to the presence of highly dispersed and small particle CuO. Moreover, CuO 3h -ZnO 400 catalyst prepared by optimized conditions can further improve the stability in ethynylation reaction due to more carbon species on the surface of ZnO. The more carbon contents in Cu–Zn catalyst contribute to the ethynylation activity and stability due to the interaction between Cu and C species favoring Cu 2 C 2 formed. In addition, the ethynylation reaction mechanism catalyzed by Cu–Zn catalyst is illustrated carefully. The Cu–Zn catalysts derived from ZIF-8 can provide some ideas for the application in ethynylation reaction of formaldehyde for 1,4-butynediol synthesis.
The peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) have been extensively studied in wastewater treatment due to their ability to generate various reactive oxygen species. However, the ultra-short half-lives of free radical species limit their effective transfer from the catalyst surfaces to the target organic contaminants for efficient decontamination. Thus, directed production of reactive species with longer lifetimes is challenging but belong with significant demand. In this study, a catalyst with neighboring Cu and Zn heteroatoms pairs anchored on the surface of zeolitic imidazolate framework (Cu/Zn-ZIF) was designed to selectively and sustainably generate radicals via PMS activation. Electron energy-loss spectroscopy (EELS) demonstrated the formation of non-bonding Cu-Zn heteroatom pairs. Owing to the synergistic effect of the Cu and Zn heteroatoms, the Cu/Zn-ZIF/PMS system achieved 99.5 % removal rate of bisphenol A (BPA) within 60 min. Therein, PMS was stabilized by the strongly adsorptive Cu/Zn-ZIF and activated within the nanoscale confinement of Cu sites, resulting in the directional generation of surface-bound • OH and SO 4 •− radicals with longer lifetimes, which facilitated the efficient removal of BPA. Significantly, it also demonstrated robust resilience against disruptions caused by intricate aquatic environments, including freshwater bodies and ionic species. These findings provide reference for theoretical research on the design of functional MOFs materials and the practical application of surface-bound radicals in AOPs.
Li-Ping Yang,Jian-Li Mi,Hui-Jie Wang,Jia-Hao Liang,Xue-Jing Yang,Yong-Hai Feng,Peng Zhang,Lu Liu
Graphical ORR and oxidation of alcohol : Bimetallic Cu−Zn co-doped porous N/C catalysts with the presence of different Cu forms show promising activity toward oxygen reduction reaction and oxidation of 1,2-propanediol. The development of non-precious metal catalysts toward oxygen reduction reaction (ORR) is essential for widespread application of fuel cells. Herein, bimetallic Cu−Zn co-doped porous N/C catalysts (Cu−Zn−N/C) with high N content were synthesized via a simple metal-organic framework (MOF)-derived method. The as-prepared Cu−Zn−N/C catalyst presents superior catalytic activity toward ORR with an onset potential of 0.90 V, a half-wave potential of 0.79 V, and a diffusion limiting current density of 5.82 mA cm −2 . It is found that Cu exists in three forms: one exists in Cu particles, and the others exist in Cu single atoms (either in high valence or in zero valence) that embedded in the carbon substrate. The evaporation of Zn atoms during the pyrolysis induces the pore structure of the carbon matrix, making it possible to support for the zero valent Cu atoms. In addition, as an efficient Cu-based catalyst for many applications, we show that the as-prepared catalyst can selectively oxidize 1,2-propanediol to lactic acid with 75.7 % selectivity at 82.8 % conversion.
危险品化学品经营许可证（带存储）