A 3D-printed metal-supported gyroid Ni/Al2O3 catalyst for CO2 methanation

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.