Applicability of LaNiO3-derived catalysts as dual function materials for CO2 capture and in-situ conversion to methane

Abstract

The valorisation of CO2 through its capture and in-situ hydrogenation to methane, using dual function materials (DFMs), emerges as promising alternative to reduce CO2 emissions to atmosphere and the global cost of current CO2 Capture and Utilization (CCU) technology. This work investigates the viability of LaNiO3-derived formulations as precursors of DFMs for CO2 capture and in-situ conversion to CH4. For this purpose, a set of DFMs obtained from 30% LaNiO3/CeO2, 30% LaNiO3/Al2O3, 30% LaNiO3/La-Al2O3 and LaNiO3 precursors were synthesized and systematically characterized before and after a controlled reduction process. Results of XRD analysis, STEM-EDX images, H2-TPR and CO2-TPD experiments reveal that the DFM obtained after reduction of 30% LaNiO3/CeO2 formulation shows the smallest Ni0 particle size (7 nm) and the highest medium-strong basic sites concentration. In fact, this DFM widens operation window with methane production ranging between 80 and 103 µmol g−1 and maintains a selectivity towards methane above 90% in the range of 280–520 °C. The best catalytic behaviour is related to a better contact between the different nature basic sites and the homogenously distributed Ni0 sites, which favours a fast spill-over of dissociated H to near CO2 adsorption sites. The applicability of this formulation is further evidenced by a highly stable CH4 production during long-term experiments and a promoted Ni0/NiO reversibility in the absence/presence of O2 during the CO2 adsorption period, which allows a fast and complete recovery of CH4 production in absence of O2. These aspects favour a versatile application of the 30% LaNiO3/CeO2-based DFM formulation to convert CO2 outlet streams from combustion flue gases of different nature.