ENGINEERING MODEL OF CATALYTIC PARTIAL OXIDATION OF METHANE TO SYNTHESIS GAS IN A FLUIDIZED-BED REACTOR

The paper presents an engineering model of the catalytic partial oxida tion of methane in a fluidized-bed reactor developed on the basis of e xperimental data obtained in a laboratory unit (ID = 5 cm) over a Ni/a lpha-Al2O3 catalyst. The model reproduced not only experimental CH4-co nversions and selectivities to CO and H-2 measured at the reactor outl et with an average accuracy of 10% but also the measured concentration profiles. The model was applied for the simulations of an industrial- scale and a pilot-scale reactor operated in the bubbling regime. Predi ctions showed that in both reactors conversions of methane and syngas yields approaching thermodynamic equilibrium can be achieved. In the i ndustrial reactor significantly higher beds compared to the laboratory unit (H-mf > 1 m) were necessary to achieve equilibrium. Simulations aiming at optimization of the hydrodynamic conditions (u(o) = 0.1-0.5 m/s; d(p) = 80-500 mu m) showed that for achieving high yields in a re latively shallow bed (H-mf = 1.6 m) low gas velocities (u = 0.1 m/s) a nd small particles (d(p) = 80 mu m) should be applied. Since performan ce of large-scale fluidized-bed reactors for the CPOM reaction are inf luenced by the transport limitations catalysts with low activity, i.e. low Ni-loading (<1%) can be used. (C) 1998 Elsevier Science S.A. All rights reserved.