COMPREHENSIVE KINETICS OF OXIDATIVE COUPLING OF METHANE OVER THE LA2O3 CAO CATALYST/

A comprehensive 10-step kinetic model of the oxidative coupling of met hane to C2+ hydrocarbons over a La2O3/CaO catalyst was developed on th e basis of kinetic measurements in a microcatalytic fixed-bed reactor covering a wide range of reaction conditions (1 < p(O2) < 20 kPa, 10 < p(CH4) < 95 kPa, 700 < T < 955 degrees C, 0.76 m(Cat)/V-STP less than or equal to 250 kg.s/m(3)). The reaction scheme contains three primar y and seven consecutive steps. The conversion of hydrocarbons and of c arbon monoxide with oxygen were described by applying Hougen-Watson ty pe rate equations. For the other reactions power-law rate equations we re used. From the experimental data kinetic parameters, i.e. frequency factors, apparent activation energies, and adsorption enthalpies, wer e estimated. With the kinetic model the experimentally determined conv ersions of methane and oxygen, as well as yields to C-2 hydrocarbons a nd carbon oxides, could be predicted with an average accuracy of +/-20 %.