On the kinetics of liquid-phase methanol synthesis over commercial Cu/ZnO/Al2O3 catalyst

Liquid-phase methanol synthesis was carried out in a slurry reactor in a te mperature range of 190-250 degrees C while the total pressure was between 2 0 and 50 bar. A commercial Cu/ZnO/Al2O3 catalyst developed to process feeds tock with higher content of CO, was used in the experimental work. The gase ous feed was composed of H-2 (25-60 vol%), CO (10-50 vol%), CO2 (2-40 vol%) , and an inert gas (nitrogen). A pure paraffin was used for the liquid phas e. The experimentally measured methanol production rates were compared with different kinetics models that appear in the open literature for liquid-ph ase methanol synthesis. It is shown that simple models, which do not accoun t for the phenomena on the catalyst surface fail to predict the rate of met hanol production in a wide range of CO2/(CO2 + CO) ratios. The results of d ynamic experiments demonstrate that a measurable amount of water is formed during the reaction and that its occurrence retards the methanol production rate. It is therefore evident that its concentration has to be considered in the adsorption term of the methanol rate equation. Using a dynamic metho d it is also confirmed that methanol production rate is proportional to CO2 concentration in the feed stream. (C) 1999 Elsevier Science Ltd. All right s reserved.