Methane partial oxidation on NiCu-based catalysts

Abstract

Catalytic Partial Oxidation of Methane (CPOM) to synthesis gas was studied over supported NiCu-based catalysts prepared by wet impregnation procedure. The samples were characterized by means of X-ray diffraction (XRD), N 2 physisorption, CO chemisorption experiments, temperature-programmed reduction (TPR), near edge (XANES) and extended (EXAFS) X-ray absorption spectroscopy. The catalyst stability was evaluated under severe reaction conditions. Reduced/preactivated Ni(10%)/Al 2O 3 shows complete CH 4 conversion above 700 °C, leading to a H 2/CO ratio of about 2 in the temperature range 850–900 °C. Vice versa, the catalytic activity of the calcined/oxidized sample is appreciably shifted towards higher temperature. Both calcined and reduced Cu(10%)/Al 2O 3 present very poor CPOM activity. Noteworthy, the performance of reduced Ni(5%)Cu(5%)/Al 2O 3 is significantly improved with respect to reduced Ni(10%)/Al 2O 3: the activity of bimetallic system is shifted by ∼150 °C towards lower temperatures. Furthermore, temperature-programmed oxidation (TPO) experiments on CPOM-aged samples showed that carbon deposition on Ni(5%)Cu(5%)/Al 2O 3 is negligible with respect to Ni(10%)/Al 2O 3.