COMPARATIVE-STUDY OF THE CATALYTIC PARTIAL OXIDATION OF METHANE TO SYNTHESIS GAS IN FIXED-BED AND FLUIDIZED-BED MEMBRANE REACTORS - PART I - A MODELING APPROACH

Catalytic partial oxidation of methane (CPOM) to synthesis gas over a Ni/alpha-Al2O3 catalyst in fixed-bed and fluidized-bed reactors with a nd without membranes was investigated by means of mathematical modelin g and simulations. The reactors were simulated by applying conditions which are of relevance for industrial applications (p=5 and 30 bar, T= 750-800 degrees C). Since, at high pressures, the performance of a fix ed-bed reactor for the CPOM reaction was strongly influenced by the in traparticle mass-transport limitation, the yield of syngas in fluidize d-bed reactor was higher compared to the fixed-bed reactor. In both re actor types, the conversion of methane and yield of syngas could be si gnificantly improved by means of integrated product separation on appl ying porous membranes. Due to the higher selectivity of separation the membrane fluidized bed was superior to the fixed bed. In turn, the hi gher selectivity of separation in fluidized-bed membrane reactors was attributed to the mass-transfer limitation between the bubble and emul sion phases that acted as a prefiltering membrane. However, the improv ement of the selectivity of separation due to the interphase gas excha nge decreased with increasing pressure. (C) 1998 Elsevier Science B.V.