Effects of CuO and La₂O₃ promoters on the ignition process of NiO/α-Al₂O₃ catalyst for catalytic partial oxidation of methane to syngas

NiO/α-Al₂O₃, NiO-CuO/α-Al₂O₃ and NiO-La₂O₃/α-Al₂O₃ catalysts were prepared by multistep impregnation method. The effects of CuO and La₂O₃ promoters on the ignition process of NiO/α-Al₂O₃ catalyst for catalytic partial oxidation of methane (CPOM) to synthesis gas were studied by temperature-programmed surface reaction (TPSR) technique as well. The results indicated that the CPOM reaction could not be ignited over the NiO/α-Al₂O₃ catalyst with or without pre-reduction during the CH₄/O₂-TPSR process till 910℃. The CPOM reaction could be ignited on the NiO-CuO/α-Al₂O₃ catalysts, which ascribed to the addition of CuO was beneficial to reduction of NiO with CH₄ and restraining the re-oxidation of Ni0 by O₂. The CPOM reaction could be ignited on the NiO-La₂O₃/α-Al₂O₃ catalysts too, which should be due to fact that the addition of La₂O₃ was beneficial to decrease the diffused resistance during the reduction process for reducing the size of nickel crystal.