Elucidation of the roles of Re in steam reforming of glycerol over Pt–Re/C catalysts

•Addition of Re to Pt/C catalyst increases the activity of glycerol steam reforming.•Steam exposure has similar effects on Pt surface for Pt/C with and without Re.•Pt–Re/C contains rhenium oxide that becomes even more oxidized upon steam exposure.•Steam exposure leads to more facile CO desorption from Pt–Re/C than that from Pt/C.•Facile CO desorption is likely due to CO spillover from Pt to neighboring Re–O(H).