Effect of transport limitations on C2+ selectivity in the oxidative methane coupling reaction using a NaOH/CaO catalyst

The dependence of C₂₊ selectivity on oxygen conversion (20 to 95%) and on particle size (0.2 mm, 1.2 mm, 4×4 mm) of the catalyst, i.e. under conditions of mass transport limitation during the oxidative coupling of methane on a NaOH/CaO catalyst was experimentally studied at three temperatures (953, 983, 1013 K) and at a partial pressure of oxygen of 0.075 bar and of methane of 0.7 bar. A kinetic reaction scheme was derived for which the overall kinetic parameters were reported. Reaction engineering calculations with respect to the particle size effect, taking into account transport phenomena, are presented and compared with experimental evidence.