The effect of catalyst composition and surface properties on the selective catalytic dehydrogenation of bioethanol

The article provides a comparative analysis of bioethanol dehydrogenation using Cr-Cu-O and Ce-Cu-O catalyst systems. For the Cr-Cu- O catalysts, bioethanol is converted into a range of products including acetaldehyde, acetone, ethylene. Advanced characterization revealed that these catalysts are structurally complex, containing not only just individual copper and chromium oxides but also a distinct compound, Cu_2 $ CrO_4 . A key finding is the clear structure-property relationship: the catalyst's crystallinity, which varied widely from 41.9% (mostly amorphous) to 73.8% (highly crystalline), has a major effect on its catalytic activity. The Ce-Cu-O system converted bioethanol into a diverse mixture of products such as acetaldehyde, acetone, and ethyl acetate, indicating the occurence of multiple simultaneous reactions, including dehydrogenation and condensation. Most compositions result in separate CeO2 and CuO phases; however, a specific Ce:Cu ratio of 1:9 is unique. At this ratio, the material reduced to form CeO_2 $ with elemental copper, rather than CuO, and its crystallinity increases from 52.7% to 71.2%. The research shows that structural order is crucial for steering the reaction pathway, as only catalysts with low crystallinity produce ethyl acetate. Furthermore, while the specific surface area of a catalyst (5.0 to 17.0 m2/g in this study) is a key factor in surface-driven reactions such as dehydrogenation, it does not affect all products equally.