Oxidative conversion of methane to CO and H₂ over Pt or Pd containing alkaline and rare earth oxide catalysts

Abstract

A number of Pt (1.0 wt%) and Pd (1.0 wt%) containing alkaline earth oxide (namely, MgO and CaO) and rare earth oxide (namely, La₂O₃, Pr₆O₁₁, Nd₂O₃, Sm₂O₃, Gd₂O₃, Dy₂O₃ and Er₂O₃) catalysts have been compared for their performance in the oxidative conversion of methane to CO and H₂ at 700 and 800°C and at very low contact time [GHSV = 5.0 (±0.2) × 10⁵ cm³.g^-1.h^-1]. The catalysts are characterized by their specific surface area and H₂ chemisorption at 40°C. Among the Pt- and Pd-containing catalysts, the best performance is shown by Pt/Gd₂O₃ and Pd/Sm₂O₃, respectively. These catalysts show high selectivity for CO but low selectivity for hydrogen due to reverse water gas shift reaction. Since alkaline and rare earth oxides are basic in nature, they act not only as a support for dispersing noble metals but also play a significant role in deciding the activity/selectivity of the Pt- or Pd-containing catalysts.