Non-steady-state and transient isotope tracer studies in methanol synthesis

Abstract

The synthesis of methanol from carbon monoxide–hydrogen and carbon monoxide–carbon dioxide–hydrogen over a copper/zinc oxide/alumina catalyst has been studied using transient isotope tracing techniques. The non-steady-state period immediately after start-up has been studied and the product distribution and time delay can be explained with reference to the amount of residual oxygen on the catalyst after reduction. Using [18O]carbon monoxide and [18O]carbon dioxide it has been shown the label is not detected in the methanol product for 0.3 h. From the steady-state activities and a residence time of 0.3 h the size of the surface reservoir of methanol precursor was calculated for both carbon monoxide–hydrogen and carbon monoxide–carbon dioxide/hydrogen feedstreams. This fugure was in good agreement with the amounts of methanol removed from the catalyst when the feedstream was switched from carbon monoxide–hydrogen or carbon monoxide–carbon dioxide–hydrogen to hydrogen alone.