Continuous CO 2 capture and methanation over Ni-Ca/Al 2 O 3 dual functional materials.

Although Ni-Ca-based dual functional materials (DFMs) have been examined for CO 2 capture and reduction with H 2 (CCR) for the synthesis of CH 4 , their performance has generally been investigated using single reactors in an oxygen-free environment. In addition, continuous CCR operations have scarcely been investigated. In this study, continuous CCR for the production of CH 4 was investigated using a double reactor system over Al 2 O 3 -supported Ni-Ca DFMs in the presence of O 2 . We found that a high Ca loading (Ni(10)-Ca(30)/Al 2 O 3 , 10 wt% Ni, and 30 wt% CaO) was necessary for reaction efficiency under isothermal conditions at 450 °C. The optimized DFM exhibited an excellent performance (46% CO 2 conversion, 45% CH 4 yield, and 97% CH 4 selectivity, respectively) and good stability over 24 h. The structure and CCR activity of Ni(10)-Ca(30)/Al 2 O 3 were studied using X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectrometry (EDS), temperature-programmed desorption (TPD), and temperature-programmed surface reaction (TPSR) techniques.