Selective dehydration of glycerol on copper based catalysts

Glycerol is produced in large quantities as a byproduct of biodiesel, and among others hydroxyacetone (acetol) is an important commodity obtained from glycerol. Metallic Cu has been identified as active site for the dehydration of glycerol to hydroxyacetone and acid and metal sites are known to influence the catalytic performance. In this study, dehydration of glycerol over 5 wt.% copper supported on ?-Al2O3, ZrO2 and SiO2 was investigated. Catalysts were characterized by N2 physisorption, H2-TPR, NH3-TPD, N2O chemisorption, XPS, XRD, FTIR of pyridine adsorption. Cu/ZrO2 exhibited the highest hydroxyacetone yield at 20 % of glycerol conversion and the highest apparent reaction rate. The superior activity of Cu/ZrO2 was attributed to the highly acidic, both Lewis and Bro?nsted acidic, nature of the support and positive roles of the interfacial sites. The Weisz-Prater (WP) criterion was applied to confirm the absence of intraparticle diffusion limitations. It was assumed spherical particles and first order reaction. The WP value obtained in the worst scenario was less than 0.3 ensuring no diffusion limitation. Complementary DFT study indicates that both glycerol and hydroxyacetone interact significantly stronger on Cu/?-Al2O3 and Cu/ZrO2 compared to metallic Cu, suggesting that the active sites are at the interface of Cu particles and the acidic support.

Automated summary

The study found that Cu/ZrO2 catalyst exhibited the highest activity and apparent reaction rate in the dehydration of glycerol to hydroxyacetone process, attributed to the highly acidic support and positive roles of interfacial sites. The application of Weisz-Prater (WP) criterion confirmed the absence of intraparticle diffusion limitations, and DFT study suggested that the active sites are located at the interface of Cu particles and the acidic support.