β-Cyclodextrin promoted the formation of copper phyllosilicate on Cu-SiO2 microspheres catalysts to enhance the low-temperature hydrogenation of dimethyl oxalate

The formation of copper phyllosilicate is critical to the hydrogenation performance of Cu-SiO2 catalysts. A series of Cu-SiO2 microsphere catalysts modified with β-cyclodextrin (β-CD) prepared by the hydrothermal method were fabricated in this work. The results showed that Cu–β-CD complexes were favored to form during the hydrothermal process, which could promote the synthesis of copper phyllosilicate. Meanwhile, the introduction of an appropriate amount of β-CD also promoted the uniform dispersion of CuO species and reduced the size of copper nanoparticles. This could increase the ratio of Cu+/Cu0 after reduction. Thereby the synergistic effect between Cu0 and Cu+ and the stability of the catalyst could be enhanced. Eventually, the modified Cu-SiO2 microsphere catalyst exhibited better catalytic activity for hydrogenation of dimethyl oxalate to ethylene glycol. The dimethyl oxalate conversion of 99.9 % and ethylene glycol selectivity of 97.5 % could be obtained at a low temperature of 453 K. This work has considerable reference value for the subsequent construction of copper species on the catalyst surface.