Fabrication of free-standing ordered porous alumina loaded with nickel nanoparticles for low temperature steam reforming of methane

Abstract

Conventional catalysts are typically supported on oxide powders in packed-bed reactors. This design becomes less efficient when used in microsystems and fuel cells because of pressure drop caused by miniaturization, and challenges on low activity at low temperatures is still not completely resolved. In this study, use of a free-standing three-dimensional porous alumina nanostructure loaded with nickel nanoparticles for steam reforming of methane was demonstrated. Alumina structure with periodic pore network was fabricated using proximity-field nanopatterning and atomic layer deposition techniques resulting to a structure with film thickness of 19 µm and shell thickness of 65 - 70 nm. Nickel, a more available and less expensive metal exhibiting catalytic activity next to noble metals, was loaded into the structure by co-impregnation process resulting to dispersed nanoparticles with an average diameter of 4.129 ± 0.798 nm with close size distribution. X-ray diffraction studies confirmed the synthesis of reduced nickel nanoparticles and EDS elemental mapping supported its uniform decoration onto the alumina structure. Resulting $Ni–3D$ $Al_2O_3$ catalyst exhibited great performance with high methane conversion compared to $Ni–Al_2O_3$ powder at temperatures 500°C – 900°C. Excellent activity at temperature as low as 600°C, and periodic pore network of the free-standing structure offer several advantages and potential in applications for low temperature hydrogen generation and utilization in small-scale devices.