Oxidative steam reforming of methane over Ni/α-Al2O3 modified with trace noble metals

Ni catalysts supported on α-Al2O3 modified with small amounts of noble metals (Pd, Pt, Au, Ir, Rh and Ru) were prepared by a co-impregnation method to investigate catalytic performance and catalyst bed temperature profile in oxidative steam reforming of methane. Modification of the Ni catalyst with noble metals was effective to decreasing the bed temperature near the catalyst bed inlet, and it is found that Pd is the most effective modifier among the noble metals. Additive effect of Pd has some aspects: the increase of the metal dispersion, suppression of oxidation and enhancement of reducibility judging from characterization results of H2 adsorption and evaluation by pulse reaction technique using O2 and H2. The extended X-ray absorption fine structure (EXAFS) analysis suggests that the excellent properties can be due to small Pd metallic cluster interacted with Ni particles.

The addition of trace noble metals (Pd, Pt, Au, Ir, Rh and Ru) over Ni/α-Al2O3 suppressed the hot-spot formation in oxidative steam reforming of methane. In particular, the addition of trace Pd to Ni/α-Al2O3 is the most effective because the small Pd clusters interacted with Ni metal particles are formed and the structure gives higher reduction rate and lower oxidation rate than other catalysts.Figure optionsDownload as PowerPoint slide