OXIDATIVE CONVERSION OF METHANE TO CO AND H-2 OVER PT OR PD CONTAINING ALKALINE AND RARE-EARTH-OXIDE CATALYSTS

A number of Pt (1.0 wt%) and Pd (1.0 wt%) containing alkaline earth ox ide (namely, MgO and CaO) and rare earth oxide (namely, La2O3, Pr6O11, Nd2O3, Sm2O3, Gd2O3, Dy2O3 and Er2O3) catalysts have been compared fo r their performance in the oxidative conversion of methane to CO and H -2 at 700 and 800 degrees C and at very low contact time [GHSV = 5.0 ( +/- 0.2) X 10(5) cm(3). g(-1) . h(-1)]. The catalysts are characteriz ed by their specific surface area and H-2 chemisorption at 40 degrees C. Among the Pt- and Pd-containing catalysts, the best performance is shown by Pt/Gd2O3 and Pd/Sm2O3, respectively. These catalysts show hig h selectivity for CO but low selectivity for hydrogen due to reverse w ater gas shift reaction. Since alkaline and rare earth oxides are basi c in nature, they act not only as a support for dispersing noble metal s but also play a significant role in deciding the activity/selectivit y of the Pt- or Pd-containing catalysts. (C) 1998 Elsevier Science Ltd . All rights reserved.