Phenylacetylene hydrogenation coupled with benzyl alcohol dehydrogenation over Cu/CeO2: A consideration of Cu oxidation state

We have examined the effect of copper oxidation state in continuous gas phase coupled phenylacetylene hydrogenation (to styrene) with benzyl alcohol dehydrogenation benzaldehyde) over Cu/CeO2. Analysis by H2-TPR, XPS, XRD and STEM-EDX analyses demonstrates generation a range Cu states (Cu0 (13–77%), Cu+ (13–74%), Cu2+ (0–55%)). The stepwise formation styrene ethylbenzene was promoted stand-alone hydrogenation. An increase Cu0/Cu+ (from H2-TPR XPS) enhanced H2 chemisorption TOF, but low hydrogen utilisation efficiency. benzaldehyde toluene alcohol, where selectivity TOF correlate concentration Cu0. Full utilisation, exclusive benzaldehyde/styrene (3-fold) greater attain 100% yield) achieved process, hydrogenation/dehydrogenation activity correlates Cu+/Cu0. This opens new directions for sustainable “hydrogen free” hydrogenations non-noble catalysts.