Ethylene from natural gas by direct catalytic oxidation

The title report describes optimizing the phys. parameters of the oxidative coupling catalyst, defining the optimum reactor design and reaction conditions, collecting data for modeling of the chem. reaction, and process design and economic evaluations. Li-doped MgO catalyst was optimized with respect to catalytic performance. Essential for the catalytic activity and selectivity is the presence of Li. The most suitable reactor was fluidized bed reactor because of the high exothermicity of the reaction. The optimum reaction conditions for reaching the max. ethylene yield (18%) for the longest time were 800°/1 atm. using a CH4/O = 5 ratio gas-feed mixt. at 0.6 g-s/mL catalyst. The reaction mechanism was described as a complicated mixt. of heterogeneous (catalytic) and homogeneous (gas phase) reactions occurring simultaneously. Coupling to ethane takes place in the gas phase. Ethane is dehydrogenated on the catalyst or in the gas phase to ethylene, which in turn gets easily oxidized into CO and CO2 which are mainly formed at the catalyst surface. A computer program was developed which simulated the network reaction (>150 elementary radical reactions) of the homogeneous gas phase.