Oxidative coupling of methane in a bubbling fluidized bed reactor

The oxidative coupling of methane to higher hydrocarbons (C 2+ ) 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, Na 2 CO 3 /CaO and PbO/γ‐Al 2 O 3 were used as catalytic materials. C 2+ selectivity depends markedly on temperature and oxygen partial pressure. The optimum temperature for maximizing C 2+ selectivity varies between 720 and 800°C depending on the catalyst. Maximum C 2+ selectivities were achieved at low oxygen and high methane partial pressures and amounted to 46% for CaO (T = 780°C; P CH 4 = 70 kPa; P O 2 = 5 kPa), 53% for Na 2 CO 3 /CaO (T = 760°C; P CH 4 = 60 kPa; P O 2 = 6 kPa) and 70% for PbO/γ‐Al 2 O 3 (T = 720°C; P CH 4 = 60 kPa; P O 2 = 5 kPa). Maximum yields were obtained at low methane‐to‐oxygen ratios; they amounted to 4.5% for CaO (T = 800°C; P CH 4 = 70 kPa; P O 2 = 12 kPa), 8.8% for Na 2 CO 3 /CaO (T = 820°C; P CH 4 = 60 kPa; P O 2 = 20 kPa) and 11.3% for PbO/γ‐Al 2 O 3 (T 2= 800°C; P CH 4 = 60 kPa; P O 2 = 20 kPa).