Production of hydrogen by catalytic reforming of dimethoxymethane over bifunctional catalysts

Reforming of hydrocarbons and oxygenated hydrocarbons is a potential way to supply H-2 for portable and household fuel cell applications. Of course, avoiding the use of toxic fuels is desirable. The extremely low toxicity of dimethoxymethane (DMM) may make it a preferred fuel for portable and household H2 sources. We found that DMM can be effectively reformed to hydrogen on specially designed complex catalysts with bifunctional characters. The complex catalysts consisted of a traditional Cu-ZnO/gamma-Al2O3 for the reforming of methanol and an acidic component for the hydrolysis of DMM. The acidity of the acidic component was found to be essential for the complex catalyst. A significant amount of dimethyl ether (DME) was produced when a strong solid acid such as H-ZSM-5 was used with the Cu-ZnO/beta-Al2O3 for the reforming of DMM. On the other hand, gamma-Al2O3 exhibited low activity for the hydrolysis of DMM, resulting in the low efficiency of the complex catalyst. Tests showed that the acidic carbon nanofibers (H-CNF) seemed suitable as the acidic component in the complex catalysts. In fact, the complex catalysts Cu-ZnO/gamma-Al2O3-H-CNF were found to exhibit excellent performance for the reforming of DMM. The rate of H-2 production from the reforming of DMM on the Cu-ZnO/gamma-Al2O3-H-CNF could be as good as that from the reforming of methanol over the traditional Cu-ZnO/gamma-Al2O3, whereas the reforming of DMM over the Cu-ZnO/gamma-Al2O3 without an acidic component exhibited low activity and produced a significant amount of DME. Mechanistic studies showed that DME was produced from DMM on the Cu surface when no additional acidic component was present. (C) 2007 Elsevier Inc. All rights reserved.