Preparation of Ni–La Based Dual Functional Materials Using Spherical Alumina and Their CO<sub>2</sub> Capture and Methanation Property

Spherical Ni–La/Al2O3 were prepared as dual functional materials (DFMs) for CO2 capture and methanation from spherical alumina using a pore-filling method. Calcination at lower temperatures is important for loading metal species in a more homogeneous manner and for obtaining better performance for CO2 capture and reduction (CCR) to CH4 under mild conditions. The highest maximum concentration, formation amount, and selectivity of CH4 were obtained using spherical Ni–La/Al2O3 calcined at 300 °C. This CCR performance was comparable to that obtained using powder-type Ni–La/Al2O3 in our previous study. The calcination at 600 °C resulted in the loading on metal species in a heterogeneous manner and a significant decrease in CCR performance. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) with analyzing the generated gas (i.e. operando DRIFTS) was also performed to investigate the reaction mechanism of CCR over Ni–La/Al2O3. The results of operando DRIFTS study suggested that CO2 was trapped on the surface of the DFM as carbonate species and then selectively converted to CH4 via surface methoxy species.