Highly Stable CO2 Methanation Catalyst Fabricated by Engineering Metal-Metal Oxide Interfaces of CoAlOx.

Preparation of a heterogeneous catalyst with ultra-high catalytic stability and target product selectivity of > 99% at near thermodynamic equilibrium conversion is the ultimate goal to pursue in the catalysis field. Here, a CoAlOx catalyst is constructed for CO2 methanation by precisely engineering metal-metal oxide interfaces. It shows CO2 conversion of > 87% and CH4 selectivity of > 99% within 3000 h at 350°C, 1 MPa and GHSV of 12 000 mL g-1 h-1. Further prolonging of reaction time to 5000 h just slightly decreases CO2 conversion to 77.5% without seriously affecting CH4 selectivity. The CH4 productivity approaches to 2463.6 mmol g-1 h-1 at GHSV of 375 000 mL g-1 h-1, being superior to reported noble metal- and transition metal-based catalysts. Such a catalytic performance stems from formation of Co0-CoO-Al2O3 microstructures with metallic Co0 nanoparticles stably trapped in atomically intimate CoO-Al2O3 material. The CoO-Al2O3 interfaces enhance CO2 adsorption and transformation into carbonates and/or bicarbonates, whereas metallic Co0 promote H2 dissociation and CO2 hydrogenation. Technical and economic analyses show that CO2 methanation could be profitable in places with abundant wind, photovoltaic, and other off-grid powers, or when the green hydrogen price is < 1103.40 US$/t, which could help build sustainable energy system in the future.