Steam reforming of ethanol over K promoted Co catalyst

•Steam reforming of ethanol over K promoted Co catalyst for efficient hydrogen production.•Promotion effect of K loading and the role of K were investigated.•Loading of 1–2 wt% K on Co/α-Al2O3 was effective for improving catalytic activity.•Co0–CoO core–shell structure was formed by K addition and shell–CoO was active for this reaction.•Adsorbed ethanol forms stable acetate species by K loading, which improves hydrogen selectivity.

We investigated the catalytic activity of Co/K/α-Al2O3 with various potassium (K) loadings for ethanol steam reforming. The promotion effect of K loading and the role of K in Co/K/α-Al2O3 were investigated using TEM–EDX, H2-TPR, XAFS, XPS, and IR measurements. Results show that loading of 1–2 wt% K on Co/α-Al2O3 was effective for improving catalytic activity, selectivity to hydrogen and suppressing by-product (CH4, C2H4, and coke) formations. Measurements by H2-TPR and XAFS showed that the reducibility of the supported Co species decreased by K loading. TEM measurements revealed that the Co0–CoO core–shell structure was formed over Co/K/α-Al2O3 during ethanol steam reforming at 823 K, suggesting that the oxidized Co species (CoO) is a highly active species in ethanol steam reforming. In situ IR measurements revealed that the adsorbed ethanol forms stable acetate species by K loading, which improves hydrogen selectivity.

Graphical abstractTEM images of Co/1K/α-Al2O3 after H2 reduction (1 h) after reaction (185 min).Figure optionsDownload full-size imageDownload high-quality image (373 K)Download as PowerPoint slide