METHANOL SYNTHESIS FROM H-2, CO, AND CO2 OVER CU/ZNO CATALYSTS

Methanol synthesis kinetics at steady state are reported for two catalysts: Cu/ZnO (as Cu : Zn 30 : 70 atomic ratio) and Cu/ZnO/Al2O3 (Cu : Zn : Al 60 : 30 : 10 atomic ratio) for various syngas compositions and temperatures from 200 to 275°C. In addition, catalyst deactivation is discussed along with XPS-Auger measurements of surface composition for fresh and used catalysts. Apparent activation energies for methanol synthesis on the Cu/ZnO catalyst depend on both temperature and fractional C02 in the COCO2 mixture and reflect a change in the importance of the CO and C02 as sources of methanol in the synthesis. The water-gas shift reaction does not proceed to equilibrium for CO mole fractions below 0.05. Experimental results confirm earlier observations that methanol is formed directly from CO and C02. However, in syngas mixtures, methanol production from CO and C02 is not just additive; some interconversion must be involved. © 1992.