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BACKGROUND: Converting the syngas‐derived dimethyl oxalate (DMO) intermediate to versatile simple diols (ethylene glycol, EG) has been deemed as a promising chemical synthesis technology, owing to the cheap, widely available raw materials. Nonetheless, finding the optimal catalyst for this route is still challenging. In this work, copper (Cu)‐doped cobalt/zinc oxide (Co/ZnO)‐based CoCu/ZnO catalysts for DMO selective hydrogenation to EG were successfully synthesized by the oxalic co‐precipitation method. RESULTS: The Cu content shows significant influence on Co dispersion and chemical features, further determining the resultant structural and morphology properties of the as‐prepared samples. For DMO gas‐phase hydrogenation, the CoCu20/ZnO catalyst prepared in presence of the 20.0 wt% Cu additive exhibited 100.0% DMO conversion and 93.0% EG yield, superior to that of the other catalysts due to adequate active Co0 sites released adjacent to the Cu species. Moreover, the CoCu/ZnO catalyst showed outstanding thermal stability in DMO‐selective hydrogenation for >200 h. CONCLUSIONS: The H2 activation ability and capability of the surface Co species depends critically on the Cu content, further regulating the reaction pathways of the DMO hydrogenation. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

In this paper, mesoporous monometallic Cu catalysts reinforced by the Al3+ dopants with different chemical features were successfully synthesized by controlling the preparation process. The N2‐Adsorption/Desorption, XRD, H2‐TPR, SEM, TEM, H2‐TPD and XPS were conducted to explore the structure evolution of the as‐synthesized samples focusing on the interface effect between Cu nano‐particles (NPs) and Al3+ dopants. It is found that the precipitants used for preparing precursors show drastically effect on the Al3+ chemical form and Cu/Al bonding manners of the as‐synthesized CuAl catalysts, further determining the resultant physicochemical properties and catalytic behavior in dimethyl oxalate (DMO) hydrogenation. In gas‐phase DMO hydrogenation, 98.0 % ethylene glycol (EG) and 90.0 % ethanol (EtOH) yield from DMO selective hydrogenation can be achieved over the CuAl catalyst by regulating the reaction temperature. The correlation between the catalytic behavior and physicochemical features shows that the surface Cu+ sites generated in the Cu/(hydr)oxide interface should be essential for DMO selective hydrogenation in presence of the adequate Cu0 sites. Additionally, the Cu−O−Al patterns in the Cu/Al interface intend to promote more electron transferred from the Al3+ dopants to Cu species through the O bridging, facilitating the CuAl(O) stronger Cu/Al interaction than that of the CuAl(C) catalyst in form of Cu−Al−OH mode. Thus, the Cu NPs growth of the CuAl(O) catalyst was effectively retarded, favoring enhanced catalytic stability. [ABSTRACT FROM AUTHOR]

Al2O3 doped mesoporous monometallic Cu catalysts were successfully synthesized though the self-assembly Cu species derived from the oxalate precursor undergoing thermal decomposing. The evolutions of microstructures, physicochemical and surface properties of the CuAl catalysts have been systematically characterized focusing on the effect of the calcination temperature during catalyst preparation. It is found that the textural and surface properties of the CuAl catalysts were profoundly affected by the calcination temperature, further determining the resultant catalytic behavior in dimethyl oxalate (DMO) hydrogenation. Particularly, the CuAl-500 possessing the maximum surface Cu+ sites and proper surface acid features exhibits 100.0% DMO conversion and 98.0% ethylene glycol (EG) selectivity in presence of the adequate active Cu0 sites, which is superior to that of the other catalysts under the identical reaction conditions. And no activity loss occurred for more than 200 h demonstrated of the outstanding stability of the CuAl-500 catalyst. Moreover, the synergistic effect between surface Cu+ and Cu0 sites should be responsible for DMO selective hydrogenation. Additionally, the strengthened chemical interaction between Cu and Al species endows the catalysts outstanding stability by suppressing the dispersive Cu NPs agglomeration during DMO hydrogenation. [ABSTRACT FROM AUTHOR]