The activity and state of the copper surface in methanol synthesis catalysts
Abstract
The measurement of copper metal surface areas by monitoring nitrous oxide chemisorption is a well established technique. A frontal chromatographic version of this technique has been developed which is very suitable for in situ measurements and this has enabled the apparent copper areas of various catalysts to be measured after exposures to methanol synthesis gases of different compositions at typical industrial conditions in microreactors commonly used for assessing the methanol synthesis activity of such catalysts. Using such techniques, it has been shown that, first, there is a linear relationship between the methanol synthesis activity of copper/zinc oxide/alumina catalysts and their total copper surface area. Second, that copper supported on other materials has approximately the same turnover number as copper/zinc oxide/alumina catalysts. Third, that under industrial conditions the copper surface of the catalyst is partially oxidised, to an extent which depends on the composition of the synthesis gas, particularly the CO2/CO ratio.
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