Graphene Aerogel Supported Ni for CO2 Hydrogenation to Methane

The graphene aerogel (GA) and graphene oxide (GO) supported Ni catalysts (Ni/GA and Ni/GO) are prepared for CO2 methanation. The Ni/GA catalyst could reach 80.4% CO2 conversion, 94.8% CH4 selectivity at 350 °C vs 68.3% CO2 conversion, 93.5% CH4 selectivity for Ni/GO at the same temperatures. The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) results show that the Ni/GA has a three-dimensional structure and is rich in porosity. The X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) spectra indicated that Ni is distributed evenly in GA. Raman spectra illustrated that GA possesses more oxygen vacancies than GO. Temperature-programmed H2 reduction (TPR) demonstrated that Ni/GA has preferable reducibility and interacted well with the supported Ni. The intermediates of methanation were identified by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), which confirms that formate is the critical intermediate for the hydrogenation of CO2 to CH4.