Effect of metal composition on hydrogen selectivity in steam reforming of methanol over catalysts prepared from amorphous alloys

Methanol steam reforming was carried out over catalysts prepared from amorp hous Cu50Zr50, (Cu50Zr50)(100-x)Au-x and (Cu50Zr50)(100-x)Pd-x alloys in a fixed bed reactor operated at atmospheric pressure. The selectivity for car bon dioxide, which is a measure of steam reforming, was dependent on the co mposition of the amorphous alloy. When the reaction was performed over Cu50 Zr50 amorphous alloy, the selectivity for carbon dioxide was essentially un ity, whereas methanol conversion was very low. On the other hand, methanol conversion increased with the palladium content over the Cu-Zr-Pd amorphous alloy, but the selectivity for carbon dioxide was lower than that over Cu- Zr alloy. When the reaction was carried out over catalysts prepared from am orphous Cu-Zr-Au alloy, the methanol conversion increased with the gold con tent, whereas the carbon dioxide selectivity was almost unity over the rang e of gold content. The surface area measurement revealed that the dispersion of copper, which was effective for the steam reforming reaction, increased with the content of gold in the amorphous alloy. On the other hand, the dispersion of pallad ium, which was effective for dehydrogenation of methanol, increased with th e palladium content. These results indicate that gold in the Cu-Zr alloy pl ays an important role in increasing the dispersion of copper. (C) 2001 Else vier Science B.V. All rights reserved.