Effects of Cu/Fe ratio on structure and performance of attapulgite supported CuFeCo-based catalyst for mixed alcohols synthesis from syngas

Abstract

The effects of Cu/Fe ratio on structure of attapulgite (ATP) supported CuFeCo-based catalysts were detected by N2 physical adsorption/desorption, XRD, H2-TPR, FE-SEM, TEM, XPS etc.. And the effect on the catalytic performance for mixed alcohols synthesis (MAS) from syngas was evaluated with a continuous flow fixed bed reactor as well. The characterization results indicated that the increase of iron addition resulted in the increase of BET surface area and facilitated the dispersion of oxide particles. Increasing iron concentration also facilitated the separation of Cu–Fe alloy phase, the incorporation of Cu and Fe species and the formation and dispersion of CuFe2O4 spinel phase, thus promoting its reduction to generate Cu–FeCx dual active site for C2+ alcohol formation. However, more Fe2O3 was formed and dispersed on/in the catalyst with higher iron concentration and was reduced to generate sole FeCx and Fe3O4 phase during reaction. The coverage of CuFe2O4 phase by Fe2O3 inhibited the mixed alcohols formation. In the MAS reaction, the Cu5.2Fe4.8 catalyst showed the highest selectivity and yield of total alcohol due to the well dispersion of high concentration of Cu-FeCx dual active site, which may be attributed to the optimum Cu–Fe interaction and the intimate contact of Cu–Fe species. In view of the utilization of low-cost nonmetallic mineral resource and the production of clean liquid fuel, the attapulgite clay has a great promise to be used as catalyst support in energy field.