Hydrogenation of CO2 to dimethyl ether on La-, Ce-modified Cu-Fe/HZSM-5 catalysts

Abstract

Cu–Fe–La/HZSM-5 and Cu–Fe–Ce/HZSM-5 bifunctional catalysts were prepared and applied for the direct synthesis of dimethyl ether (DME) from CO2 and H2. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption–desorption, H2-temperature programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The results showed that La and Ce significantly decreased the outer-shell electron density of Cu and improved the reduction ability of the Cu–Fe catalyst in comparison to the Cu–Fe–Zr catalyst, which may increase the selectivity for DME. The Cu–Fe–Ce catalyst had a greater specific surface area than the Cu–Fe–La catalyst. This promoted CuO dispersion and decreased CuO crystallite size, which increased both the DME selectivity and the CO2 conversion. The catalysts were stable for 15h.