Characterization of fused Fe–Cu based catalyst for higher alcohols synthesis and DRIFTS investigation of TPSR

Abstract

Fused Fe–Cu based catalyst for higher alcohols synthesis (HAS) is characterized by XRD, TG–DTA, H 2-TPD and DRIFTS of CO adsorption. The results of XRD reveal that the fused Fe–Cu based catalyst consists of Cu 2O, CuFeO 2 and CuFe 2O 4 species. After reduction, the metallic Fe and Cu are the main species, but minor CuFeO 2 and CuFe 2O 4 species are also present. H 2-TPD shows that in comparison with the pure Fe- or Cu-based sample, the ability of Fe–Cu based catalyst for activation of H 2 is higher and the stronger metal–hydrogen bonds are formed. DRIFTS of CO adsorption indicates that CO is adsorbed on both metal and metal ion sites, where the dissociation of CO to C* and O* species and the formation of CO 2 are observed. In situ DRIFTS investigation of CO + H 2-TPSR over the Fe–Cu based catalyst shows that the dissociative activation of H 2 is more difficult than the activation of CO, and carbonaceous and hydrocarbon fragment species only appears after the dissociative activation of H 2. In addition, HAS over the Fe–Cu based catalyst is very complicated, where various intermediates including = CH 2, − CHO, − OOCH, − OH and − C(= O)–R exist.