Design, Implementation and Experimental Evaluation of an Additively Manufactured SiSiC Reactor for Catalytic Steam Reforming

Hydrogen from biogenic sources is central to the transition to a carbon-neutral energy system, offering flexibility for mobility and industrial applications. Decentralized steam reforming of biogas enables on-site hydrogen production but requires precise heat management due to its strongly endothermic nature. In small-scale systems, conventional manufacturing approaches often limit geometric flexibility and thermal integration, whereas additive manufacturing enables highly integrated reactor structures that overcome these constraints. This study presents the development and experimental evaluation of a compact, monolithic reformer additively manufactured from silicon-infiltrated silicon carbide, combining combustion and reforming zones in a single component to enhance heat transfer and compactness. The reactor features an internal U-shaped reforming channel filled with a nickel-based catalyst and was tested under varying loads. CH4 conversions of 95–99% close to equilibrium were achieved at gas hourly space velocities up to 75,000 h−1. Stable internal heat supply sustained reforming, although combustion results remain preliminary due to manufacturing-related blockages in the combustion channels, as revealed by computed tomography (CT) analysis. Energy assessments indicate that thermal efficiency is primarily limited by external heat losses of up to 46%, resulting from the high operating temperatures and small reactor dimensions. The results demonstrate the feasibility of the integrated reactor concept while highlighting current limitations related to manufacturability and heat losses, providing a basis for future optimization and scale-up.