ALKALI-PROMOTED MOS2 CATALYSTS FOR ALCOHOL SYNTHESIS - THE EFFECT OF ALKALI PROMOTION AND PREPARATION CONDITION ON ACTIVITY AND SELECTIVITY

Abstract

The effect of alkali species addition to MoS2 catalyst has been studied to have a better understanding of the relationship between alcohol synthesis and basicities of alkali-promoted catalyst. The selectivity for alcohol formation increased in the order Li < Na < Cs < Rb < K, indicating moderately basic additives are desired. The activity for the alcohol formation is strongly dependent on the counter anion of the potassium salts, increasing in the order, halides < SO4 < CH3COO=CO3 < OH. This order is consistent with the order of the acidity of each conjugate base, revealing a strong basic alkali promotion is required for the formation of alcohols over MoS2. Potassium-promoted MoS2 is oxidized while stored in the atomosphere or even in a vacuum oven at room temperature for several weeks. The oxidized catalyst showed enhanced catalytic activity and high selectivity to C2+hydrocarbons, rather than forming alcohols as fresh catalyst did.