Morphology Effects of Nanoscale Er2O3 and Sr-Er2O3 Catalysts for Oxidative Coupling of Methane

Er2O3 nanorods were prepared by a hydrothermal method, and Sr-modified Er2O3 nanorods (Sr-Er2O3) were synthesized using an impregnation method. Their catalytic performance for oxidative coupling of methane was investigated. The catalysts were characterized by several techniques such as XRD, N2 adsorption, TEM, XPS, O2-TPD and CO2-TPD. Compared with Er2O3 and Sr-Er2O3 nanoparticles, Er2O3 and Sr-Er2O3 nanorods exhibit higher CH4 conversion and C2–C3 selectivity. This is caused by higher (O− + O2−)/O2− ratio, a higher number of chemisorbed oxygen species and moderate basic sites achieved on the nanorods catalysts. The Sr-Er2O3 nanorods afford a 23.2% conversion of CH4 with 50.3% selectivity to C2–C3 at 650 °C.