Ni-Al₂O₃/Ni-foam catalyst with enhanced heat transfer for hydrogenation of CO₂ to methane

Monolithic Ni-Al₂O₃/Ni-foam catalyst is developed by modified wet chemical etching of Ni-foam, being highly active/selective and stable in strongly exothermic CO₂ methanation process. The as-prepared catalysts are characterized by x-ray diffraction scanning electron microscopy, inductively coupled plasma atomic emission spectrometry, and H₂-temperature programmed reduction-mass spectrometry. The results indicate that modified wet chemical etching method is working efficiently for one-step creating and firmly embedding NiO-Al₂O₃ composite catalyst layer (~2 μm) into the Ni-foam struts. High CO₂ conversion of 90% and high CH₄ selectivity of >99.9% can be obtained and maintained for a feed of H₂/CO₂ (molar ratio of 4/1) at 320°C and 0.1 MPa with a gas hourly space velocity of 5000 h^-1, throughout entire 1200 h test over 10.2 mL such monolithic catalysts. Computational fluid dynamics calculation and experimental measurement consistently confirm a dramatic reduction of "hotspot" temperature due to enhanced heat transfer.