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

Abstract

Methanol steam reforming was carried out over catalysts prepared from amorphous Cu 50Zr 50, (Cu 50Zr 50) 100− x Au x and (Cu 50Zr 50) 100− x Pd x alloys in a fixed bed reactor operated at atmospheric pressure. The selectivity for carbon dioxide, which is a measure of steam reforming, was dependent on the composition of the amorphous alloy. When the reaction was performed over Cu 50Zr 50 amorphous alloy, the selectivity for carbon dioxide was essentially unity, 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 amorphous Cu–Zr–Au alloy, the methanol conversion increased with the gold content, whereas the carbon dioxide selectivity was almost unity over the range 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 palladium, which was effective for dehydrogenation of methanol, increased with the palladium content. These results indicate that gold in the Cu–Zr alloy plays an important role in increasing the dispersion of copper.