Preparation of Ni–La Based Dual Functional Materials Using Spherical Alumina and Their CO₂ Capture and Methanation Property

Abstract

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.