Performance of an internally circulating fluidized‐bed reactor for the catalytic oxidative coupling of methane

The oxidative coupling of methane to C 2 ‐hydrocarbons (OCM) over a La 2 O 3 /CaO catalyst (27 at.%) was investigated in an internally circulating fluidized‐bed (ICFB) reactor ( ID eff = 1.9 cm, H riser = 20.5 cm). The experiments were performed in the following range of conditions: T = 800−900°C, p CH 4 : p O 2 p N 2 = 57.1–64:16–22.9:20 kPa. The obtained C 2 selectivities and C 2 yields were compared with the corresponding data from a spouted‐fluid‐bed reactor ( ID = 5 cm) and a bubbling fluidized‐bed (FIB) reactor ( ID = 5 cm). The maximum C 2 yield in the internally circulating fluidized‐bed (ICFB) reactor amounted to 12.2% ( T = 860°C, 38.7% C 2 selectivity, 31.5% methane conversion), whereas in the FIB reactor a maximum C 2 yield of 13.8% ( T = 840°C, 40.4% C 2 selectivity, 34.2% methane conversion) was obtained. The lowest C 2 yield was achieved in the spouted‐bed (SFB) reactor ( Y   c   2= 11.6%, T = 840°C, 36.2% C 2 selectivity, 32.0% methane conversion). The highest space‐time yield of 24.0 mol/kg cat .h was obtained in the ICFB reactor, whereas in a FIB reactor only a space‐time yield of 9.6 mol/kg cat could be obtained. The performance of the ICFB reactor was strongly influenced by gas‐phase reactions. Furthermore, stable reactor operation was possible only over a narrow range of gas velocities.