Oxidative coupling of methane in a bubbling fluidized bed reactor

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Abstract
The oxidative coupling of methane to higher hydrocarbons (C2+) was studied in a bubbling fluidized bed reactor between 700°C and 820°C, and with partial pressures of methane from 40 to 70 kPa and of oxygen from 2 to 20 kPa; the total pressure was ca 100 kPa. CaO, Na2CO3/CaO and PbO/γ‐Al2O3were used as catalytic materials. C2+selectivity depends markedly on temperature and oxygen partial pressure. The optimum temperature for maximizing C2+selectivity varies between 720 and 800°C depending on the catalyst. Maximum C2+selectivities were achieved at low oxygen and high methane partial pressures and amounted to 46% for CaO (T = 780°C; PCH4= 70 kPa; PO2= 5 kPa), 53% for Na2CO3/CaO (T = 760°C; PCH4= 60 kPa; PO2= 6 kPa) and 70% for PbO/γ‐Al2O3(T = 720°C; PCH4= 60 kPa; PO2= 5 kPa). Maximum yields were obtained at low methane‐to‐oxygen ratios; they amounted to 4.5% for CaO (T = 800°C; PCH4= 70 kPa; PO2= 12 kPa), 8.8% for Na2CO3/CaO (T = 820°C; PCH4= 60 kPa; PO2= 20 kPa) and 11.3% for PbO/γ‐Al2O3(T 2= 800°C; PCH4= 60 kPa; PO2= 20 kPa).