OXIDATIVE COUPLING OF METHANE OVER A LA2O3 CAO CATALYST - OPTIMIZATION OF REACTION CONDITIONS IN A BUBBLING FLUIDIZED-BED REACTOR/

Oxidative coupling of methane over a La2O3/CaO catalyst was investigat ed in laboratory-scale fluidized-bed reactors (LD = 5 and 7 cm) in the following range of reaction conditions: T = 700 - 880 degrees C, P-CH 4 = 41 - 72 kPa and P-O2 = 6 - 29 kPa. The maximum C-2+ selectivity an d yield amounted to 73.8% (T = 800 degrees C; X(CH4) = 13.1%, Y-C2+ = 9.7%) and 16.0% (T = 840 degrees C, X(CH4) = 34.0%, S-C2+ = 47.2%), re spectively. Axial gas concentration profiles revealed that C-2+ select ivity was not only influenced by oxidative consecutive reactions, but also by steam reforming of ethylene. When diluting the catalytic bed ( m(cat) = 145 g) with quartz (m(SiO2) = 200 and 400 g), a slight decrea se of the selectivity (1-2%) was observed. The dilution of the feed ga s with nitrogen only led to only a small increase (< 2%) of the C-2+ s electivity.