The synergistic effect of Pd NPs and UiO-66 for enhanced activity of carbon dioxide methanation

Carbon dioxide methanation is of great importance for both environment and energy because of the reduction of carbon dioxide emissions and the utilization of carbon source. In this work, UiO-66 was employed as the support for palladium nanoparticles via a sol-gel method to enhance the activity of CO2 methanation. The physical-chemical properties of as-prepared catalysts were characterized using N2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscope (TEM), temperature programmed desorption (TPD), temperature programmed reduction (TPR), thermo-gravimetric analysis (TGA), Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that there was a synergistic effect between UiO-66 and supported Pd. CO2 could be activated in UiO-66 via its Zr6O4(OH)4 nods, while H2 molecules were dissociated at Pd for further hydrogenation of activated CO2. As a result, the catalyst with a Pd loading of 6 wt.% exhibited a high activity with 56.0% of CO2 conversion and 97.3% of CH4 selectivity, corresponding to a STY of 856 g·h−1·kgcat−1 at 4 MPa and 340 °C.