Effects of La_2O_3 on ZrO_2 supported Ni catalysts for autothermal reforming of CH_4

摘要

The effect of La_2O_3 content in Ni-La-Zr catalyst was investigated for the autothermal reforming (ATR) of CH,. The catalysts were prepared by the coprecipitation method and had a mesoporous structure. Temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS) indicated that a strong interaction developed between Ni species and the support with the addition of La_2O_3. Thermogravimetric analysis (TGA) and H_2-pulse chem-isorption showed that the addition of La_2O_3 led to well dispersed NiO molecules on the support. Ni-La-Zr catalysts gave much higher CH_4 conversion than Ni-Zr catalyst. The Ni-La-Zr containing 3.2 wt% La_2O_3 showed the highest activity. The optimum conditions for maximal CH_4 conversion and H_2 yield were H_2O/CH_4=1.00, O_2/CH_4=0.75. Under these conditions, CH_4 conversion of 83% was achieved at 700 ℃. In excess O_2 (O_2/CH_4>0.88), the catalytic activity was decreased due to sintering of the catalyst.