Hydrogenation of levulinic acid to γ-valerolactone over copper catalysts supported on γ-Al2O3

•Reaction scheme: hydrogenation of levulinic acid to γ-valerolactone.•The vapor-phase hydrogenation of levulinic acid to γ-valerolactone by using Cu/γ-Al2O3 catalysts.•The copper-supported catalysts were prepared by wet impregnation method.•The catalytic activity studies during hydrogenation of levulinic acid are directly related to the dispersion of copper.•The regenerated catalyst showed comparatively good catalytic activity.

The vapor-phase hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) was investigated over copper catalysts supported on γ-Al2O3. The catalysts were prepared by wet impregnation method by varying Cu loadings from 2 to 20 wt% on γ-Al2O3. The calcined samples were characterized by X-ray diffraction, UV-DRS, atomic absorption spectroscopy (AAS), temperature-programmed reduction (TPR), temperature-programmed desorption (TPD-NH3), scanning electron microscopy (SEM), transmission electron microscopy (TEM), surface area and pore size distribution measurements. Dispersion of copper was determined by the N2O decomposition method. XRD patterns exhibited two intense reflections due to CuO for the catalysts containing above 5 wt% copper loading. TPR results reveal that the surface copper oxide species on the support is more easily reduced than the bulk CuO. N2O decomposition results suggest that copper oxide is well dispersed on the support up to 5 wt% Cu loading and the dispersion decreases steadily at higher copper loading. Copper dispersion and particle size were obtained from N2O decomposition method are well in agreement with the findings derived from XRD and TPR. The catalytic functionalities during hydrogenation of levulinic acid are discussed in relation to the dispersion of copper and other structural properties of Cu species supported on γ-Al2O3.

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