Steam reforming of methane on a Ru/Al2O3 catalyst promoted with Mn oxides for solar hydrogen production

Abstract

A new type of solar heated reformers have been developed in recent years. In these reactors, called volumetric reformers, concentrated solar radiation directly illuminates the catalyst through a transparent window. This new type of solar reformer can operate at higher temperatures (1000–1100 °C), since the surface temperature limit of a regular metal tube reactor used in the industry is eliminated and a much higher heating rate is feasible. In the last few years the Weizmann Institute has gathered experience in developing high temperature steam reforming catalysts for its “DIAPR-Kippod” based volumetric reformer. The configuration of the absorber in this reformer is an array of ceramic pins. The thermal stability of the catalysts is crucial for the viability of such reactors. Ru/Al₂O₃ catalysts promoted with Mn oxides are studied. The effect of Mn on the dispersion and sintering of the Ru particles is investigated in the present work with the aid of TEM and EDS. It was found that addition of Mn oxides decreases in the rate of the sintering of the Ru particles. Catalytic elements for use in a volumetric reformer have been developed and tested. The Ru/Al₂O₃ catalyst promoted with Mn oxides was supported on ceramic pins (made of alumina) by wash coating. The long-term test confirmed the chemical and thermal stability of the catalyst even after operating for 500 hours at 1100 °C.