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

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Abstract
The oxidative coupling of methane to C2‐hydrocarbons (OCM) over a La2O3/CaO catalyst (27 at.%) was investigated in an internally circulating fluidized‐bed (ICFB) reactor (IDeff = 1.9 cm, Hriser = 20.5 cm). The experiments were performed in the following range of conditions: T = 800−900°C, pCH4:pO2pN2 = 57.1–64:16–22.9:20 kPa. The obtained C2 selectivities and C2 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 C2 yield in the internally circulating fluidized‐bed (ICFB) reactor amounted to 12.2% (T = 860°C, 38.7% C2 selectivity, 31.5% methane conversion), whereas in the FIB reactor a maximum C2 yield of 13.8% (T = 840°C, 40.4% C2 selectivity, 34.2% methane conversion) was obtained. The lowest C2 yield was achieved in the spouted‐bed (SFB) reactor (Y = 11.6%, T = 840°C, 36.2% C2 selectivity, 32.0% methane conversion). The highest space‐time yield of 24.0 mol/kgcat.h was obtained in the ICFB reactor, whereas in a FIB reactor only a space‐time yield of 9.6 mol/kgcatcould 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.