COMPARATIVE-STUDY OF THE PARTIAL OXIDATION OF METHANE TO SYNTHESIS GAS IN FIXED-BED AND FLUIDIZED-BED MEMBRANE REACTORS - PART II - DEVELOPMENT OF MEMBRANES AND CATALYTIC MEASUREMENTS

The catalytic partial oxidation of methane (CPOM) to synthesis gas was carried out in fixed-bed and fluidized-bed membrane reactors over a N i/alpha-Al2O3 catalyst. For gas separation silicalite membranes inside an alumina and a porous stainless-steel matrix were synthesized and a pplied in the catalytic measurements. Moreover, a membrane obtained by deposition of palladium on the stainless-steel silicalite membrane wa s tested. The zeolite membranes were stable in the whole investigated temperature range (700<T<750 degrees C). The Pd-membrane was not stabl e; palladium layer did not withstand temperatures above 650 degrees C. In the catalytic measurements in the fixed-bed reactor and in the flu idized bed (P-CH4 = 66.6 kPa,P-O2 = 33.3 kPa, m(cat)/V=14 gs/ml) nearl y thermodynamic equilibrium was achieved. However, neither in the fixe d-bed reactor nor in the fluidized-bed membrane reactor an improvement in the syngas yield by means of the integrated product separation cou ld be achieved. In the tired-bed membrane the unselective separation o f methane was detrimental for methane conversion. In the fluidized-bed membrane reactor the amount of permeated hydrogen was not sufficient to shift significantly the equilibrium towards higher syngas yield. Ho wever, in the fluidized-bed membrane reactor significant better select ivities of separation were achieved. (C) 1998 Elsevier Science B.V.