Catalysis Letters, Vol.78, No.1-4, 49-55, 2002
Alcohol synthesis from syngas over K2CO3/CoS/MoS2 on activated carbon
Supported K2CO3/Co-MoS2 on activated carbon was prepared by a co-impregnation technique and has been characterized by X-ray diffraction (XRD) and BET Active ingredients ranged from 39 to 66% and included molysulfide and cobalt sulfide. XRD analysis indicates that cobalt and molybdenum sulfides are found in the Co3S4 and Co9S8 phases. These catalysts, were performance tested in a fixed-bed reactor under higher alcohol synthesis conditions, 2000-2400 psig and 270-330 degreesC. Active chemicals on the carbon extrudates decreased the surface area dramatically, as measured by BET. Surprisingly, at the high level of active chemicals, alcohol productivity and selectivity were decreased. An increase in the reaction temperature led to a decrease in the selectivity of methanol and an increase in selectivity of hydrocarbons. Total alcohol productivity was also increased as gas hourly space velocity (GHSV) was increased. Co9S8 may play a role in the catalyst aging process. In prolonged reaction periods (140 h), sulfur is lost from the surface, possibly as H2S. The quantity of Co9S8 on the surface appears to increase as the catalyst ages.