Direct oxidation of methane to methanol at atmospheric pressure in CMR and RSCMR

SiO2 (I) and Mo-Co-O/SiO2 (II) microporous membranes supported on porous ceramic substrate were prepared using the sol-gel method. Their structures were characterized using SEM, XRD and pore size measurement techniques. An organic additive is useful for the preparation of (I) and could improve the whole surface of the capping SiO2 and its pore size distribution. Using the (II) and (I) membranes, the catalytic membrane reactor (CMR) and the reactant-swept catalytic membrane reactor (RSCMR), have been composed to investigate the oxidation of methane to methanol by air at atmospheric pressure and at 500-700 degrees C. When the pressure difference between the two sides of the CMR was equal to 0.5 kPa, a good yield of methanol was obtained. The CMR using (II) microporous membrane supported on (I) of pore radius larger than 4 nm results in poor catalytic activity. Under similar reaction conditions at 1.0% methane conversion, the methanol selectivity is 11.2% in CMR and 4.5% in FBR. For the RSCMR at temperatures below 600 degrees C, the methanol yield is similar to that obtained using CMR. At temperatures above 600 degrees C the methanol yield in RSCMR is higher than that in CMR, e.g. at 700 degrees C the methanol yield is 0.5 g/m(2) h in CMR and 0.9 g/m(2) h in RSCMR.