Ni–Ca–Al Synergistic Effect in Dual-Function Materials for Integrated CO2 Capture and Conversion

Integrated carbon capture and utilization (ICCU), based on dual-function materials (DFMs), is an emerging technology for carbon dioxide (CO2) emission control. DFMs composed of Ni–Ca–Al systems are favored owing to their affordability. However, their performance needs to be further improved. In this study, Ni/AlCaOx DFMs are prepared by one pot-impregnation method, reaching an adsorbing capacity of 1796 μmol CO2/gDFM and a production of 1790 μmol CH4/gDFM after ten cycles at 450 °C. The Ni–Ca–Al synergistic effect was investigated to understand the good performance of DFMs: during H2 pretreatment, Ca can weaken the strong interaction of Al–Ni and promote the reduction of NiO by facilitating Ni to gain electrons from H2, where Al may act as an intermediate carrier for electron transfer. In the carbonation process, Al modulates the synergistic interaction between Ca and Ni by regulating the spacing and distribution of catalytic and adsorption sites to improve the Ni/AlCaOx cycling performance. Besides, oxygen vacancies can also enhance the DFMs' carbon capture performance. During the methanation process, Ni reduces the decomposition temperature of the carbonate formed at strongly basic sites, favoring the methanation reaction.