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

Abstract

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 and ethylene. Advanced characterization revealed that these catalysts are structurally complex, containing not only individual copper and chromium oxides but also a distinct compound, Cu₂CrO₄. 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 occurrence of multiple simultaneous reactions, including dehydrogenation and condensation. Most compositions resulted in separate CeO₂ and CuO phases; however, a specific Ce:Cu ratio of 1:9 is unique. At this ratio, the material is reduced to form CeO₂ with elemental copper, rather than CuO, and its crystal­linity increased from 52.7 to 71.2 %. The research showed 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.