EFFECTS OF PHASE-COMPOSITION AND OF POTASSIUM PROMOTION ON COBALT MOLYBDATE CATALYSTS FOR THE SYNTHESIS OF ALCOHOLS FROM CO2 AND H-2

Cobalt molybdate and cobalt molybdate-potassium catalysts were found t o exhibit activity for alcohol formation from Cod H-2 at 3.0 MPa and 2 50 degrees C and 300 degrees C. Tetrahedrally coordinated Mo6+ ions fa vor the selectivity to alcohols. Addition of K2CO3 greatly enhances th e selectivity of the reaction to methanol. The extent of this effect w as dependent on the way the alkali metal was mixed with the catalyst. Catalysts obtained by mechanical mixing of alpha-CoMoO4 and K2CO3 deac tivate faster than the beta-CoMoO4/K mixture calcined at 550 degrees C , where formation of a K2MoO4 phase was detected by XRD. Both catalyst s show a similar maximum in selectivity to alcohols at around 90 min o f reaction. Addition of potassium by coprecipitation along with Co and Mo, which leads to the formation of K2CO2(MoO4)(3), also enhances alc ohol production, but the effect is more attenuated than for the other promoted samples. (C) 1998 Elsevier Science B.V. All rights reserved.