دانلود رایگان مقاله آماده سازی اسپینل کبالت مس و آلومینیوم برای اکسیداسیون کل بنزن

Abstract

Mixed metal oxides Co5 − xCuxAl (x = 0–0.5) were prepared from Co-Cu-Al layered double hydroxides (LDHs) and tested for benzene total oxidation. By calcination, Co-Cu-Al LDHs were mainly transformed to (Co, Cu)(Co, Al)2O4 spinels, where both Cu2 + and Al3 + cations were incorporated into the spinel structure. The incorporation of Cu significantly improved the Co oxide reducibility and remarkably enhanced the light-off activity as well as the total conversion activity, indicative a strong interaction between Cu2 + and Co3 + active sites. The optimum Co4.75Cu0.25Al spinel mixed oxide was comparable with a 0.3%Pd/γ-Al2O3 catalyst, highlighting the promoting effect of structural modification with Cu.

4. Conclusions

The structural and catalytic properties of Co5 − xCuxAl mixed oxides changed significantly with Cu content. At low Cu content (x ≤ 0.25), both Cu2+ and Al3+ cations were incorporated into the Co3O4 structure to form (Co, Cu)(Co, Al)2O4 spinel. At higher Cu content, excess Cu separated from the spinel to form bulk CuO. The Co oxide reducibility was significantly improved by the presence of Cu, suggesting a strong interaction between Co3+/Co2+ and Cu2+ species. The catalytic activity of Co-Al spinel was enhanced by the presence of a small amount of Cu (x ≤ 0.25), while excess Cu addition decreased the catalytic activity. The enhanced activity might be related to the improved reducibility of Co3+ active species.