A 3D-printed metal-supported gyroid Ni/Al₂O₃catalyst for CO₂methanation

The utilization of 3D-printing in catalyst production for CO2 methanation has emerged as a response to the challenges posed by the highly exothermic reaction and high gas space velocity, conditions that necessitate enhanced heat and mass transfer while maintaining optimal catalytic performance. In this work, we developed a new CO2 methanation catalyst comprising a Ni/Al2O3 powder-coated 3D-printed aluminum alloy of gyroid configuration. The metallic alloy (AlMgSi) was 3D-printed (3DAL) using selective laser melting (SLM), and Ni/Al2O3 powder was coated on it by washcoating. Microscopy and tomography techniques were employed to examine the morphological characteristics of the catalyst and to analyze internal topology, and hydrogen temperature-programmed reduction (H2-TPR) and chemisorption provided insights into the reduction sites and active metal phase. The catalytic performance was assessed through CO2 methanation experiments at various temperatures ranging from 250 °C to 500 °C, using a CO2:H2:He gas mixture (1:4:5). The 3D-printed Ni/Al2O3-3DAL catalyst exhibited high CH4 selectivity (97.7%) and CO2 conversion (77.6%) at 400 °C, which is attributed to the reduced tendency of sintering and the effective heat transfer owing to the metallic support. The 3D-printed gyroid metallic support provided a higher surface area-to-volume ratio enabling higher catalyst loading per unit volume, and improved reactants contact with the active catalyst phase yielding enhanced catalytic performance compared to powder. It also offers enhanced thermal energy management and heat dissipation, which are critical for highly exothermic reactions such as CO2 methanation, as well as mechanical strength compared to conventional beads and pellets.