Hydrotalcite derived Cu-Zn-Cr catalysts admixed with γ-Al2O3 for single step dimethyl ether synthesis from syngas: Influence of hydrothermal treatment

The Cu-Zn-Cr catalysts derived from hydrotalcite (HT) structures were prepared by the hydrothermal and non-hydrothermal methods. The catalysts were admixed with Al2O3 to synthesize DME (dimethyl ether) from syngas. XRD analysis revealed the presence of hydrotalcite (HT)-like structures in the oven dried form was decomposed to disperse copper species in the calcined conditions. ESR spectra of the fresh calcined catalysts disclosed both the isolated and clustered copper species and bulk Cr3+ species are seen in used catalysts. The TPR analysis indicated that the Cu2+ ions are reduced in two stages. DME synthesis experiments showed that the CO conversion and DME yield were linearly correlated with Cu metal surface areas of Cu-Zn-Cr catalysts admixed with γ-Al2O3. Activity results indicated that hydrothermal treatments have pronounced influence on the dispersion of copper species and consequently on DME synthesis rates.