Deciphering the role of Cu0 and Cuσ+ in engendering the hydrogen production from glycerol reforming over Cu/CeO2: The effect of different Cu precursors

Copper-based catalysts have been widely reported as remarkable candidates in reforming processes; however, they often suffer from poor stability, sintering, and deactivation over extended periods under high-temperature conditions. Hitherto, the information of the mechanism of the Cu precursor that induces the strong metal-support interaction over the Cu-based catalysts, the role of Cu 0 and Cu σ+ that engendered the reforming, and the stabilization of Cu facets remain limited in the literature. Here, we demonstrate that copper-acetate-based catalyst supported on CeO 2 (Cu/CeO 2 (A)) is a promising candidate for glycerol reforming in terms of stability and reforming efficiency compared to sulphate and nitrate-based Cu/CeO 2 catalysts. Through a series of characterization analyses (H 2 -TPR, H 2 -TPD, XPS, N 2 O, HRTEM, Raman spectroscopy, in-situ DRIFTS, and variable-temperature PXRD), the presence of Cu δ+ species in the Cu/CeO 2 were found to be the main active sites for promoting the reforming and CO activation. Whereas the Cu 0 and oxygen vacancies of CeO 2 were to aid in facilitating the glycerol decomposition. Moreover, the in-situ synchrotron-FTIR microspectroscopy further shows that the ratio of Brönsted: Lewis acidic active sites ratio of Cu/CeO 2 (A) (in high spatial-resolution mode) remained stable between 0.17 and 0.18, for both physisorbed and chemisorbed, indicating that the main acidic sites promoting the glycerol dissociative and adsorption were on the LS sites. Notably, a remarkable performance of 95.1 % of glycerol conversion and 80.8 vol.% H 2 production were obtained under the reaction condition of Cu species loading = 10 wt.%, reaction temperature 600 °C, glycerol concentration = 10 wt.%, and WHSV =1.953 h −1 . • The Cu σ+- Ov-Ce 3+ (O v = oxygen vacancy) interface plays a vital role in glycerol reforming process. • 95 % of glycerol conversion with 80.8 vol% H 2 production were attained under the optimum condition. • The role of Brönsted and Lewis active sites in the Cu/CeO 2 in enhancing the H 2 spillover has been elucidated. • The role of active sites of Cu/CeO 2 in giving rise the liquid and gaseous products have been discussed.