REACTION OF METHANE AND SULFUR - OXIDATIVE COUPLING AND CARBON-DISULFIDE FORMATION

Reaction between methane and sulfur vapor (mainly S2) has been studied at 773-1073 K in the presence of possible catalysts and in the absence of a catalyst. Reaction was carried out in a silica tube reactor at a total pressure of 1 atm with excess methane, with prereaction sulfidation using H2S/H-2. Sm2O3 had significant catalytic effect on CH4 conversion, but all other potential catalysts (including Li/MgO) gave CH4 conversion close to that in the absence of catalyst. CS2 was the major product, accompanied by C2 coupling product which in most cases was predominantly C2H4 with some C2H6. In some cases, small amounts of C3, C4 hydrocarbons and CH3SH, (CH3)2S, (CH3)2S2 were also found. Experiments with varying space velocity indicated that C2H6 was the primary coupling product. Possible reaction pathways are discussed in terms of homogeneous CH 3-generation, augmented by CH3. generated heterogeneously at the surface of sulfided Sm2O3. Sulfidation of Li/MgO is considered to be the reason for the inactivity of this potential catalyst.