Direct Conversion of Methane to Value-Added Hydrocarbons over Alumina-Supported Cobalt Modified by Alkaline Earth Catalysts

Methane can be directly converted to valuable hydrocarbons (C2+) via oxidative coupling of methane (OCM). The current work intensively investigated 20 weight percentage (20 wt%) of cobalt supported on alumina (20Co/Al2O3) modified with alkaline earth metals (Mg, Ca, Sr, and Ba), prepared using the wet impregnation method. The catalysts were tested in a fixed-bed reactor at atmospheric pressure. Notably, the 20Co/Al2O3 catalysts modified with Ca and Sr were highly active at low reactor temperatures (460-610 ?). The most active catalyst was 20Co/Al2O3 loaded with 2.5 wt% Sr, achieving the highest C2+ yield of 3.0%, with 10.6% C2+ selectivity and 27.8% methane conversion at 580 ?. In addition, the effects of various operating conditions were investigated: total feed flow rate, total catalyst weight, reactor temperature, and feed gas ratio. A time-on-stream test of the most outstanding catalyst revealed that its catalyst durability was excellent for 24 h of testing at 580 ?.{GRAPHIACAL ABSTRACT}