Influence of the addition of promoters to steam reforming catalysts

The steam reforming of hydrocarbons may be catalyzed by several transition metals. The most frequently used catalysts are α-Al2O3 supported nickel-based catalysts, which are frequently modified by the addition of promoters such as Mg and Ca, in order to improve their stability and selectivity. The mechanism of promotion was investigated using temperature programmed surface reaction (TPSR), diffuse reflectance UV-vis spectroscopy (DRS) and temperature-programmed oxidation. The DRS spectra showed bands characteristic to NiO with Al3+ and NiO with less interaction with the support. Temperature programmed surface reaction results showed that there is an increase in the reforming activity by the presence of the promoters, without modification in the mechanism of reaction. The TPO results showed that the addition of promoters caused an increase on the hydrogen content of the coke formed.