Effects of the preparation methods on the performance of the Cu-Cr-Fe/Y-Al2O3 catalysts for the synthesis of 2-methylpiperazine

摘要

Co-precipitation, impregnation and ultrasonic sol-gel (USG) methods have been used to prepare Cu-Cr-Fe/Y-Al2O3 catalysts, which were further used to synthesize 2-methylpiperazine. The catalysts were characterized by XRD, XPS, TG/DSC, BET, TPR, AAS and TEM. It is found that preparation method can greatly impact the catalytic performance of the catalysts, the Cu-Cr-Fe/γ-Al2O3 catalyst prepared by the ultrasonic sol-gel method proved to be the most active and stable for this reaction. The dispersion and stabilization of Cu° in the reduced catalysts are attributed to the existence of CuCr2O4 and Fe2O3. A surprising copper migration was detected by XPS analysis for the Cu-Cr-Fe/γ-Al2O3-USG catalyst after the calcination process, which may be crucial to the high activity and stability of this catalyst.