Bifunctional Catalyst with a Yolk-Shell Structure Catalyzes Glucose to Produce Ethylene Glycol

The preparation of small molecule compounds with a high value from biomass has always been the focus of research, and catalysts with high activity and stability are an essential part of biomass conversion. In this work, yolk-shell nanospheres (YSNSs) with the high hydrogenation activity metal Pd as the core and mesoporous silica as the shell were prepared firstly, and then the bifunctional catalyst Pd@WOx-MSiO2 YSNSs was obtained by loading tungsten oxide on the surface of yolk-shell nanospheres. The structure characterization showed that the prepared Pd@WOx-MSiO2 YSNSs had a good shell-void-core structure, the amorphous WOx species was uniformly dispersed on the surface and channel of the mesoporous silica shell, and there were no bulky WO3 crystals. A series of Pd@WOx-MSiO2 YSNSs catalysts with different tungsten contents were used to catalyze the directional preparation of ethylene glycol (EG) from glucose. The conversion of glucose was 99.3% and the selectivity of EG was 59.4%. According to the analysis of the acidity of the catalyst and the valence state of the metal, the catalyst had weak Lewis acidity, which could promote the cleavage of the C-C bond in glucose, and W5+ could produce oxygen vacancy to adsorb oxygen into glucose, so that the tungsten species can effectively promote the selectivity of EG. Pd@WOx-MSiO2 YSNSs were very different from other supported catalysts in structure and the distribution of active sites. Compared with traditional supported catalysts, Pd@WOx-MSiO2 YSNSs had higher activity and stability due to their unique yolk-shell structures and the protection of the inner Pd nanoparticles by the mesoporous silica shell.

Automated summary

Pd@WOx-MSiO2 YSNSs catalysts with yolk-shell structures showed higher activity and stability compared to traditional supported catalysts, due to the unique distribution of active sites and protection of inner Pd nanoparticles by mesoporous silica shell.